Escenario: HTTPs e SNI
Sumario
Introdución
Esquema de rede do escenario.
Configuración do escenario
Configuración do server
Tómase como punto de partida o servidor web ó remate do escenario anterior. Un punto a ter en conta á hora de implantar esta práctica é que van convivir no mesmo servidor sitios web https cun socket propio e sitios web https compartindo o mesmo socket grazas a SNI.
Se vos resulta complicado ou con vistas a montalo en prácticas co alumnado e para distinguir as dúas técnicas preferides que non convivan no mesmo server, o único que habería que facer é eliminar as IPs adicionais e deshabilitar os sitios web de www.tenda1.example e www.tenda2.example co comando a2dissite.
Para deshabilitar os sitios tendaprobas, tanto por http como por https:
$ sudo a2dissite www.tenda1.example.conf $ sudo a2dissite www.tenda1.example-ssl.conf $ sudo a2dissite www.tenda2.example.conf $ sudo a2dissite www.tenda2.example-ssl.conf $ sudo systemctl reload apache2 $ sudo apache2ctl -S
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1. Set the 'ServerName' directive globally to suppress this message VirtualHost configuration: *:80 127.0.0.1 (/etc/apache2/sites-enabled/000-default.conf:1) ServerRoot: "/etc/apache2" Main DocumentRoot: "/var/www/html" Main ErrorLog: "/var/log/apache2/error.log" Mutex ssl-stapling: using_defaults Mutex ssl-cache: using_defaults Mutex default: dir="/var/run/apache2/" mechanism=default Mutex watchdog-callback: using_defaults Mutex ssl-stapling-refresh: using_defaults PidFile: "/var/run/apache2/apache2.pid" Define: DUMP_VHOSTS Define: DUMP_RUN_CFG User: name="www-data" id=33 Group: name="www-data" id=33
Configurar a resolución DNS dende os clientes
Para poder acceder ós sitios web dende os clientes hai que configurar a resolución dns. Igual que no escenario anterior hai dúas solucións:
- Instalar un servidor dns cunha zona para cada un dos dominios probas1.example, probas2.example e probas3.example
- Nos equipos cliente poden engadirse as entradas correspondentes ós hosts www.probas1.example, www.probas2.example e www.probas3.example no arquivo hosts.
Aínda que non é a mellor solución, por ser un escenario de probas escolleuse a segunda por ser a máis rápida e sinxela.
A modo de exemplo así quedaría o arquivo hosts dun cliente linux:
$ cat /etc/hosts 127.0.0.1 localhost 127.0.1.1 lxd 192.0.2.11 www.tenda1.example 192.0.2.12 www.tenda2.example 192.0.2.13 www.probas1.example www.probas2.example www.probas3.example # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters
SNI
No escenario anterior cada dominio accesible por https tiña un socket (IP/porto) adicado. As razóns hai que buscalas no funcionamento do protocolo http e na forma de establecemento da canle cifrada SSL/TLS. Supoñamos por un momento que un servidor web teña unha única IP para todos os dominios aloxados; por exemplo, www.tendaprobas1.com e www.tendaprobas2.com. Nesta situación, cando o servidor web Apache recibe unha solicitude http dun cliente, revisa a cabeceira Host da solicitude para ver cal dos dominios aloxados (virtualhosts baseados en nome) é o que lle interesa ó cliente. Desta forma, pode consultar o arquivo de configuración correcto e recuperar a información pedida polo cliente. Na seguinte imaxe pode observarse unha solicitude http onde na cabeceira Host especifícase que o dominio de interese é www.tendaprobas1.com:
Mensaxe http coa cabeceira Host especificando o dominio www.tendaprobas1.com
Fig. Cabeceira HTTP coa cabeceira Host indicando o sitio web de interese
Se usamos https é de supoñer que o cliente debería recibir o certificado asociado ó dominio polo que pregunta cando se vaia a establecer a canle SSL/TLS. Pero aquí é onde aparece o problema; xa que durante as mensaxes intercambiadas para crear a canle SSL/TLS, non se especifica o dominio e a canle cifrada crease antes de que o cliente envíe a solicitude http coa cabeceira Host. Polo tanto, o servidor Apache non sabe que certificado usar por que non sabe que dominio concreto quere visitar o cliente:
SSL/TLS sen SNI
Fig. Establecemento dunha canle SSL/TLS e a problemática do certificado a usar
Se cada dominio está nunha IP (ou socket) diferente, este problema desaparece ó non poder equivocarse o servidor, xa que o único que ten que facer o servidor é usar o certificado do sitio web asociado á IP onde contacta o cliente:
SSL/TLS sen SNI pero con varias IPs
Fig. Establecemento de canles SSL/TLS usando sockets adicados a cada sitio web
A solución un dominio-unha IP funciona, pero desaproveita direccións. Para superar esta limitación creouse unha extensión de TLS chamada SNI (Server Name Indication), onde o cliente durante o establecemento da canle TLS indica o dominio ó que se quere conectar; permitindo desta forma que o servidor web seleccione o certificado axeitado.
SSL/TLS con SNI
Fig. Establecemento da canles SSL/TLS usando SNI
A continuación pode verse nos seguintes paquetes capturados co sniffer Wireshark o establecemento da conexión entre o cliente e o servidor. No primeiro podemos ver como o cliente envía o nome de dominio na extensión SNI do TLS e no segundo a resposta do servidor enviando o certificado correspondente:
Establecemento SSL/TLS con extensisón SNI
Fig. O cliente establece a conexión e indica o dominio de interese (www.tendaprobas1.com) na extensión SNI
Establecemento SSL/TLS con extensisón SNI - resposta do servidor
Fig. Resposta do servidor enviando o certificado axeitado para www.tendaprobas1.com
SNI fai que un servidor poida utilizar múltiples certificados nunha mesma dirección IP e número de porto, permitindo que múltiples sitios web seguros (https) poidan ser servidos nunha mesma IP sen que todos os sitios compartan un certificado común. Este concepto é equivalente ó concepto de host virtuais baseados en nome de http/1.1 pero para https. SNI non está limitado a https, estando dispoñible para calquera outro servizo que funcione sobre TLS.
Non todos, pero a gran maioría dos navegadores, servidores e proxys web soportan SNI e na seguinte URL pode verse unha listaxe listaxe concreta.
Apache con HTTPS e SNI
Sitio por defecto
O sitio por defecto será o sitio ó que vaia Apache cando reciba unha petición http destinada a unha IP-porto e que non se poida asignar a un virtualhost concreto ó comparar a cabeceira Host e a directiva ServerName dos virtualhosts activos no servidor. O acceso por http ó sitio por defecto xa está activado no escenario anterior e procederemos a activar o acceso por https que usan os certificado snake-oil:
sudo nano /etc/apache2/sites-available/000-default.conf
<VirtualHost 192.0.2.13:80>
ServerAdmin webmaster@localhost
DocumentRoot /var/www/html
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
sudo nano /etc/apache2/sites-available/default-ssl.conf
<IfModule mod_ssl.c>
<VirtualHost 192.0.2.13:443>
ServerAdmin webmaster@localhost
...
SSLEngine on
# A self-signed (snakeoil) certificate can be created by installing
# the ssl-cert package. See
# /usr/share/doc/apache2/README.Debian.gz for more info.
# If both key and certificate are stored in the same file, only the
# SSLCertificateFile directive is needed.
SSLCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem
SSLCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key
...
sudo a2ensite default-ssl.conf sudo systemctl reload apache2 sudo apache2ctl -S
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1. Set the 'ServerName' directive globally to suppress this message VirtualHost configuration: 192.0.2.11:443 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example-ssl.conf:1) 192.0.2.11:80 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example.conf:1) 192.0.2.12:443 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example-ssl.conf:1) 192.0.2.12:80 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example.conf:1) 192.0.2.13:80 server5C (/etc/apache2/sites-enabled/000-default.conf:1) 192.0.2.13:443 server5C (/etc/apache2/sites-enabled/default-ssl.conf:2) ServerRoot: "/etc/apache2" Main DocumentRoot: "/var/www/html" Main ErrorLog: "/var/log/apache2/error.log" Mutex watchdog-callback: using_defaults Mutex ssl-stapling-refresh: using_defaults Mutex ssl-stapling: using_defaults Mutex ssl-cache: using_defaults Mutex default: dir="/var/run/apache2/" mechanism=default PidFile: "/var/run/apache2/apache2.pid" Define: DUMP_VHOSTS Define: DUMP_RUN_CFG User: name="www-data" id=33 Group: name="www-data" id=33
Nos arquivos de configuración do sitio por defecto /etc/apache2/sites-enabled/000-default.conf e /etc/apache2/sites-enabled/default-ssl.conf o DocumentRoot está definido como /var/www/html. Para modificar a páxina index.html hai que editala:
$ sudo nano /var/www/html/index.html
<html> <head><title>Sitio Web por defecto</title></head> <body> <b>Sitio Web por defecto</b> </body> </html>
Accedendo cun navegador a 192.0.2.13 por http e https (aceptando o certificado autoasinado 'snakeoil') cárgase a páxina principal:
Sitio Web por defecto
Sitio Web por defecto https
Fig. Acceso por http e https ó sitio por defecto
Sitio www.probas1.example
Segundo o enunciado, o acceso ó dominio www.probas1.example é unicamente a través de http; polo tanto, creamos un arquivo de configuración para acceder por http a www.probas1.example:
$ sudo nano /etc/apache2/sites-available/www.probas1.example.conf
<VirtualHost 192.0.2.13:80>
ServerName www.probas1.example
ServerAdmin webmaster@probas1.example
DocumentRoot /var/www/probas1.example
ErrorLog ${APACHE_LOG_DIR}/probas1.example_error.log
CustomLog ${APACHE_LOG_DIR}/probas1.example_access.log combined
</VirtualHost>
Creación do directorio especificado no DocumentRoot e creación da páxina index.html do sitio:
$ sudo mkdir /var/www/probas1.example $ sudo nano /var/www/probas1.example/index.html
<html> <head><title>Sitio de PROBAS 1</title></head> <body> <b>Sitio de PROBAS 1</b> </body> </html>
Activación do sitio e verificación:
$ sudo a2ensite www.probas1.example.conf $ sudo systemctl reload apache2 $ sudo apache2ctl -S ...
VirtualHost configuration:
192.0.2.11:443 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example-ssl.conf:1)
192.0.2.11:80 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example.conf:1)
192.0.2.12:443 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example-ssl.conf:1)
192.0.2.12:80 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example.conf:1)
192.0.2.13:443 server5C (/etc/apache2/sites-enabled/default-ssl.conf:2)
192.0.2.13:80 is a NameVirtualHost
default server server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost www.probas1.example (/etc/apache2/sites-enabled/www.probas1.example.conf:1)
...
Fixarse como no mesmo socket <192.0.2.13,tcp,80> están dous sitios web diferentes (o sitio por defecto e www.probas1.example). Grazas a cabeceira Host que envía o cliente web, o servidor Apache sabe que páxina servir.
Acceso a www.probas1.example por http:
Sitio Web probas1
Fig. Acceso por http ó sitio www.probas1.example
No caso de acceder a www.probas1.example por https ocurrirá o seguinte:
A resolución dns de www.probas1.example é 192.0.2.13 (a IP do servidor web). O cliente web vai á IP 192.0.2.13 porto 443 e pide a páxina principal do dominio www.probas1.example Como non hai ningún sitio web no servidor que cumpra co anterior, o servidor web envía o certificado snakeoil e no caso de aceptalo devolve o sitio web por defecto. Sitio Web por defecto https
Fig. Acceso por https ó sitio www.probas1.example
Sitio www.probas2.example
Segundo o enunciado, o acceso ó dominio www.probas2.example será tanto de http coma de https; polo tanto teremos que crear dous arquivos de configuración, un para acceder por http e outro para acceder por https. Ademais, o acceso á carpeta segredo do sitio web ten que ser por https, bloqueándose o acceso no caso de facelo por http. Obrigar a usar https para acceder a un recurso pode facerse a través da directiva de configuración SSLRequireSSL.
Procedemos a crear o arquivo de configuración para http:
$ sudo nano /etc/apache2/sites-available/www.probas2.example.conf
<VirtualHost 192.0.2.13:80>
ServerName www.probas2.example
ServerAdmin webmaster@probas2.example
DocumentRoot /var/www/probas2.example
<Directory /var/www/probas2.example/segredo>
SSLRequireSSL
</Directory>
ErrorLog ${APACHE_LOG_DIR}/probas2.example_error.log
CustomLog ${APACHE_LOG_DIR}/probas2.example_access.log combined
</VirtualHost>
Creamos o directorio especificado en DocumentRoot e editamos a páxina index.html do sitio:
sudo mkdir /var/www/probas2.example sudo nano /var/www/probas2.example/index.html
<html> <head><title>Sitio de PROBAS 2</title></head> <body> <b>Sitio de PROBAS 2</b> </body> </html>
Creamos a carpeta segredo e editamos a páxina index.html da carpeta segredo:
sudo mkdir /var/www/probas2.example/segredo sudo nano /var/www/probas2.example/segredo/index.html
<html> <head><title>TOP SECRET</title></head> <body> <b>TOP SECRET</b> </body> </html>
Creamos o certificado dixital autoasinado e gardámos o certificado e a clave privada na carpeta /etc/apache2/certificados:
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache2/certificados/www.probas2.example.key -out /etc/apache2/certificados/www.probas2.example.crt
Generating a 2048 bit RSA private key ................+++ .........................................+++ writing new private key to '/etc/apache2/certificados/www.probas2.example.key' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:ES State or Province Name (full name) [Some-State]:España Locality Name (eg, city) []:Santiago Organization Name (eg, company) [Internet Widgits Pty Ltd]:Probas2 S.A. Organizational Unit Name (eg, section) []: Common Name (e.g. server FQDN or YOUR name) []:www.probas2.example Email Address []:admin@probas2.example
A continuación creamos o arquivo de configuración para https:
$ sudo nano /etc/apache2/sites-available/www.probas2.example-ssl.conf
<VirtualHost 192.0.2.13:443>
ServerName www.probas2.example
ServerAdmin webmaster@localhost
DocumentRoot /var/www/probas2.example
SSLEngine on
SSLCertificateFile /etc/apache2/certificados/www.probas2.example.crt
SSLCertificateKeyFile /etc/apache2/certificados/www.probas2.example.key
ErrorLog ${APACHE_LOG_DIR}/probas2.example_error.log
CustomLog ${APACHE_LOG_DIR}/probas2.example_access.log combined
</VirtualHost>
Activamos o sitio ww.probas2.example tanto por http como por https:
$ sudo a2ensite www.probas2.example.conf $ sudo a2ensite www.probas2.example-ssl.conf $ sudo systemctl reload apache2 $ sudo apache2ctl -S
...
VirtualHost configuration:
192.0.2.11:443 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example-ssl.conf:1)
192.0.2.11:80 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example.conf:1)
192.0.2.12:443 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example-ssl.conf:1)
192.0.2.12:80 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example.conf:1)
192.0.2.13:443 is a NameVirtualHost
default server server5C (/etc/apache2/sites-enabled/default-ssl.conf:2)
port 443 namevhost server5C (/etc/apache2/sites-enabled/default-ssl.conf:2)
port 443 namevhost www.probas2.example (/etc/apache2/sites-enabled/www.probas2.example-ssl.conf:1)
192.0.2.13:80 is a NameVirtualHost
default server server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost www.probas1.example (/etc/apache2/sites-enabled/www.probas1.example.conf:1)
port 80 namevhost www.probas2.example (/etc/apache2/sites-enabled/www.probas2.example.conf:1)
...
Agora temos que:
- No socket <192.0.2.13,tcp,80> hai tres sitios web (por defecto, www.probas1.example e www.probas2.example) e novamente grazas á cabeceira Host o servidor sabe cal debe servir.
- No socket <192.0.2.13,tcp,443> hai dous sitios web (por defecto e www.probas2.example) e grazas á SNI o servidor sabe que certificado debe servir para establecer a canle cifrada, e permitir ó cliente autenticar ó servidor (saber se está conectado co verdadeiro server).
Analizando a saída do comando apache2ctl podemos ver que:
- No port tcp/80 están dispoñibles o servidor por defecto, o sitio www.probas1.example e o sitio www.probas2.example.
- No port tcp/443 están dispoñibles o servidor por defecto e o sitio www.probas2.example.
Probamos a acceder por http e https a www.probas2.example:
Sitio Web probas2
Sitio Web probas2 https
Fig. Fig. Acceso por http e https ó sitio www.probas2.example
No caso de acceder por http á carpeta segredo aparecerá un erro ó estar prohibido este tipo de acceso:
Cartafol segredo
Fig. Erro ó acceder por http á carpeta segredo do sitio www.probas2.com
Os erros de acceso por http a segredo quedan recollidos nos logs do sitio:
$ cat /var/log/apache2/probas2.example_error.log
... [Sun May 07 19:31:56.352785 2023] [ssl:error] [pid 3090:tid 140003761964800] [client 192.0.2.1:56556] AH02219: access to /var/www/probas2.example/segredo failed, reason: SSL connection required ubuntu@server5C:~$
Pero o acceso por https está autorizado:
Cartafol segredo
Fig. Acceso autorizado por https á carpeta segredo do sitio www.probas2.example
Sitio www.probas3.example
Creación do arquivo de configuración para http. Emprégase a directiva Redirect para reenviar ós clientes que acceden por http a unha conexión segura https:
$ sudo nano /etc/apache2/sites-available/www.probas3.example.conf
<VirtualHost 192.0.2.13:80>
ServerName www.probas3.example
ServerAdmin webmaster@probas3.example
DocumentRoot /var/www/probas3.example
Redirect permanent / https://www.probas3.example/
ErrorLog ${APACHE_LOG_DIR}/probas3.example_error.log
CustomLog ${APACHE_LOG_DIR}/probas3.example_access.log combined
</VirtualHost>
Edición da páxina index.html do sitio:
$ sudo mkdir /var/www/probas3.example $ sudo nano /var/www/probas3.example/index.html
<html> <head><title>Sitio de PROBAS 3</title></head> <body> <b>Sitio de PROBAS 3</b> </body> </html>
Creación certificado dixital:
$ sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache2/certificados/www.probas3.example.key -out /etc/apache2/certificados/www.probas3.example.crt
Generating a 2048 bit RSA private key ..+++ ...........+++ writing new private key to '/etc/apache2/certificados/www.probas3.example.key' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:ES State or Province Name (full name) [Some-State]:España Locality Name (eg, city) []:Santiago Organization Name (eg, company) [Internet Widgits Pty Ltd]:Probas3 S.A. Organizational Unit Name (eg, section) []:Dpto. Ventas Common Name (e.g. server FQDN or YOUR name) []:www.probas3.example Email Address []:admin@probas3.example
Creación do arquivo de configuración para https:
sudo nano /etc/apache2/sites-available/www.probas3.example-ssl.conf
<VirtualHost 192.0.2.13:443>
ServerName www.probas3.example
ServerAdmin webmaster@probas3.example
DocumentRoot /var/www/probas3.example
SSLEngine on
SSLCertificateFile /etc/apache2/certificados/www.probas3.example.crt
SSLCertificateKeyFile /etc/apache2/certificados/www.probas3.example.key
ErrorLog ${APACHE_LOG_DIR}/probas3.example_error.log
CustomLog ${APACHE_LOG_DIR}/probas3.example_access.log combined
</VirtualHost>
Activación do sitio ww.probas3.example:
$ sudo a2ensite www.probas3.example.conf $ sudo a2ensite www.probas3.example-ssl.conf $ sudo systemctl reload apache2 $ sudo apache2ctl -S
...
VirtualHost configuration:
192.0.2.11:443 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example-ssl.conf:1)
192.0.2.11:80 www.tenda1.example (/etc/apache2/sites-enabled/www.tenda1.example.conf:1)
192.0.2.12:443 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example-ssl.conf:1)
192.0.2.12:80 www.tenda2.example (/etc/apache2/sites-enabled/www.tenda2.example.conf:1)
192.0.2.13:443 is a NameVirtualHost
default server server5C (/etc/apache2/sites-enabled/default-ssl.conf:2)
port 443 namevhost server5C (/etc/apache2/sites-enabled/default-ssl.conf:2)
port 443 namevhost www.probas2.example (/etc/apache2/sites-enabled/www.probas2.example-ssl.conf:1)
port 443 namevhost www.probas3.example (/etc/apache2/sites-enabled/www.probas3.example-ssl.conf:1)
192.0.2.13:80 is a NameVirtualHost
default server server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost server5C (/etc/apache2/sites-enabled/000-default.conf:1)
port 80 namevhost www.probas1.example (/etc/apache2/sites-enabled/www.probas1.example.conf:1)
port 80 namevhost www.probas2.example (/etc/apache2/sites-enabled/www.probas2.example.conf:1)
port 80 namevhost www.probas3.example (/etc/apache2/sites-enabled/www.probas3.example.conf:1)
...
O acceso por http é redirixido a https grazas a directiva Redirect. Analizando o log probas3.example_access.log podemos ver o código de resposta 301 do servidor ante a petición da páxina principal do sitio e como na seguinte liña vólvese a recibir a mesma solicitude e o servidor proporciona a resposta (código 200).
$ cat /var/log/apache2/probas3.example_access.log
... 192.0.2.1 - - [07/May/2023:20:46:38 +0000] "GET / HTTP/1.1" 301 586 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/112.0" 192.0.2.1 - - [07/May/2023:20:46:41 +0000] "GET / HTTP/1.1" 200 2664 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/112.0" 192.0.2.1 - - [07/May/2023:20:46:41 +0000] "GET /favicon.ico HTTP/1.1" 404 520 "https://www.probas3.example/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/112.0" ...
Sitio Web probas3
Fig. Acceso por https ó sitio www.probas3.example
Conclusión
Vemos que é posible acceder a diferentes sitios correndo no mesmo socket (IP-porto) por https grazas a SNI e o envío por parte do cliente do nome de dominio na extensión SNI do TLS.
Na seguinte imaxe podemos ver o paquete Client Hello durante o establecemento da canle cifrada para https://www.probas2.example
SNI probas2.example
Fig. Extensión SNI indicando o sitio www.probas2.example
Na seguinte imaxe podemos ver o paquete Client Hello durante o establecemento da canle cifrada para https://www.probas3.example
Fortificando HTTPS
Os últimos anos foron un desastre para os protocolos SSL/TLS ó aparecer varias vulnerabilidades que fixeron que a gran maioría das versións e implementacións destes protocolos estén consideradas a día de hoxe como 'mortas'.
Algunhas das vulnerabilidades máis salientables dende o ano 2011 e lograron que a día de hoxe unicamente sexa considerado seguro TLS:
- BEAST
- CRIME
- Heartbleed
- Reverse Heartbleed
- POODLE
- FREAK
- Logjam
No sitio web de seguridade security by default hai un interesante artigo onde se fala destas vulnerabilidades e do estado do SSL nos concellos, onde revisaban varias webs empregando a solución online SSL Server Test de Qualys SSL Labs.
Debido a todos os problemas indicados, novas vulnerabilidades que aparecen e a unha maior concienciación en materia de seguridade, a día de hoxe as configuracións SSL/TLS dos servidores web empezan a vir con valores por defecto seguros, e en moitos casos pouco ou nada hai que retocar. A pesar disto, é unha boa práctica revisar o estado da configuración e modificala para fortificala. Para axudarnos nesta tarefa existen ferramentas que automatizan a análise e proporcionan indicacións das accións a levar:
Análise online
Qualys SSL oferta análises do estado do SSL tanto dun servidor web como das capacidades SSL/TLS dun cliente web.
O problema da análise do servidor web é que éste ten que estar na web, polo tanto no noso escenario teremos que recorrer a outro software.
Análises internas
Existen diversas ferramentas que permiten realizar este tipo de análises e vermos dúas: testssl e nmap.
testssl testssl.sh é unha ferramenta de liña de comandos que permite testar a seguridade SSL/TLS sen necesidade de que o server teña que estar exposto en Internet. Para poder usala procedemos á descargala e descomprimila:
$ git clone --depth 1 https://github.com/drwetter/testssl.sh.git $ cd testssl.sh/ ~/testssl.sh $ ls -lhF
drwxrwxr-x 2 asir asir 4,0K feb 7 22:58 bin/ -rw-rw-r-- 1 asir asir 22K feb 7 22:58 CHANGELOG.md -rw-rw-r-- 1 asir asir 5,7K feb 7 22:58 Coding_Convention.md -rw-rw-r-- 1 asir asir 2,0K feb 7 22:58 CONTRIBUTING.md -rw-rw-r-- 1 asir asir 5,3K feb 7 22:58 CREDITS.md drwxrwxr-x 2 asir asir 4,0K feb 7 22:58 doc/ -rw-rw-r-- 1 asir asir 3,1K feb 7 22:58 Dockerfile -rw-rw-r-- 1 asir asir 1,4K feb 7 22:58 Dockerfile.alpine -rw-rw-r-- 1 asir asir 3,6K feb 7 22:58 Dockerfile.md drwxrwxr-x 2 asir asir 4,0K feb 7 22:58 etc/ -rw-rw-r-- 1 asir asir 6,9K feb 7 22:58 FAQ.md -rw-rw-r-- 1 asir asir 18K feb 7 22:58 LICENSE -rw-rw-r-- 1 asir asir 62K feb 7 22:58 openssl-iana.mapping.html -rw-rw-r-- 1 asir asir 11K feb 7 22:58 Readme.md drwxrwxr-x 3 asir asir 4,0K feb 7 22:58 t/ -rwxrwxr-x 1 asir asir 1,3M feb 7 22:58 testssl.sh* drwxrwxr-x 2 asir asir 4,0K feb 7 22:58 utils/ Lanzamos a análise contra www.probas2.example:
~/testssl.sh $ ./testssl.sh --wide https://www.probas2.example
#####################################################################
testssl.sh version 3.3dev from https://testssl.sh/dev/
(79db276 2026-01-15 15:19:45)
This program is free software. Distribution and modification under
GPLv2 permitted. USAGE w/o ANY WARRANTY. USE IT AT YOUR OWN RISK!
Please file bugs @ https://testssl.sh/bugs/
#####################################################################
Using OpenSSL 1.0.2-bad (Mar 28 2025) [~179 ciphers]
on incus:./bin/openssl.Linux.x86_64
Testing all IPv4 addresses (port 443): 192.0.2.13
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Start 2026-02-07 22:59:40 -->> 192.0.2.13:443 (www.probas2.example) <<--
A record via: /etc/hosts
rDNS (192.0.2.13): www.probas1.example. www.probas2.example. www.probas3.example.
Service detected: HTTP
Testing protocols via sockets except NPN+ALPN
SSLv2 not offered (OK)
SSLv3 not offered (OK)
TLS 1 not offered
TLS 1.1 not offered
TLS 1.2 offered (OK)
TLS 1.3 offered (OK): final
QUIC Local problem: No OpenSSL QUIC support
NPN/SPDY not offered
ALPN/HTTP2 http/1.1 (offered)
Testing cipher categories
NULL ciphers (no encryption) not offered (OK)
Anonymous NULL Ciphers (no authentication) not offered (OK)
Export ciphers (w/o ADH+NULL) not offered (OK)
LOW: 64 Bit + DES, RC[2,4], MD5 (w/o export) not offered (OK)
Triple DES Ciphers / IDEA not offered
Obsoleted CBC ciphers (AES, ARIA etc.) offered
Strong encryption (AEAD ciphers) with no FS offered (OK)
Forward Secrecy strong encryption (AEAD ciphers) offered (OK)
Testing server's cipher preferences
Hexcode Cipher Suite Name (OpenSSL) KeyExch. Encryption Bits Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
SSLv2
-
SSLv3
-
TLSv1
-
TLSv1.1
-
TLSv1.2 (no server order, thus listed by strength)
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 521 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
xc028 ECDHE-RSA-AES256-SHA384 ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
xc014 ECDHE-RSA-AES256-SHA ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
x9f DHE-RSA-AES256-GCM-SHA384 DH 2048 AESGCM 256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 521 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xccaa DHE-RSA-CHACHA20-POLY1305 DH 2048 ChaCha20 256 TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xc0a3 DHE-RSA-AES256-CCM8 DH 2048 AESCCM8 256 TLS_DHE_RSA_WITH_AES_256_CCM_8
xc09f DHE-RSA-AES256-CCM DH 2048 AESCCM 256 TLS_DHE_RSA_WITH_AES_256_CCM
x6b DHE-RSA-AES256-SHA256 DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
x39 DHE-RSA-AES256-SHA DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA
xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 521 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384
xc4 DHE-RSA-CAMELLIA256-SHA256 DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256
x88 DHE-RSA-CAMELLIA256-SHA DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA
x9d AES256-GCM-SHA384 RSA AESGCM 256 TLS_RSA_WITH_AES_256_GCM_SHA384
xc0a1 AES256-CCM8 RSA AESCCM8 256 TLS_RSA_WITH_AES_256_CCM_8
xc09d AES256-CCM RSA AESCCM 256 TLS_RSA_WITH_AES_256_CCM
x3d AES256-SHA256 RSA AES 256 TLS_RSA_WITH_AES_256_CBC_SHA256
x35 AES256-SHA RSA AES 256 TLS_RSA_WITH_AES_256_CBC_SHA
xc0 CAMELLIA256-SHA256 RSA Camellia 256 TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256
x84 CAMELLIA256-SHA RSA Camellia 256 TLS_RSA_WITH_CAMELLIA_256_CBC_SHA
xc051 ARIA256-GCM-SHA384 RSA ARIAGCM 256 TLS_RSA_WITH_ARIA_256_GCM_SHA384
xc053 DHE-RSA-ARIA256-GCM-SHA384 DH 2048 ARIAGCM 256 TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384
xc061 ECDHE-ARIA256-GCM-SHA384 ECDH 521 ARIAGCM 256 TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 521 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
xc027 ECDHE-RSA-AES128-SHA256 ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
xc013 ECDHE-RSA-AES128-SHA ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
x9e DHE-RSA-AES128-GCM-SHA256 DH 2048 AESGCM 128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
xc0a2 DHE-RSA-AES128-CCM8 DH 2048 AESCCM8 128 TLS_DHE_RSA_WITH_AES_128_CCM_8
xc09e DHE-RSA-AES128-CCM DH 2048 AESCCM 128 TLS_DHE_RSA_WITH_AES_128_CCM
xc0a0 AES128-CCM8 RSA AESCCM8 128 TLS_RSA_WITH_AES_128_CCM_8
xc09c AES128-CCM RSA AESCCM 128 TLS_RSA_WITH_AES_128_CCM
x67 DHE-RSA-AES128-SHA256 DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
x33 DHE-RSA-AES128-SHA DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA
xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 521 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
xbe DHE-RSA-CAMELLIA128-SHA256 DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
x45 DHE-RSA-CAMELLIA128-SHA DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA
x9c AES128-GCM-SHA256 RSA AESGCM 128 TLS_RSA_WITH_AES_128_GCM_SHA256
x3c AES128-SHA256 RSA AES 128 TLS_RSA_WITH_AES_128_CBC_SHA256
x2f AES128-SHA RSA AES 128 TLS_RSA_WITH_AES_128_CBC_SHA
xba CAMELLIA128-SHA256 RSA Camellia 128 TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256
x41 CAMELLIA128-SHA RSA Camellia 128 TLS_RSA_WITH_CAMELLIA_128_CBC_SHA
xc050 ARIA128-GCM-SHA256 RSA ARIAGCM 128 TLS_RSA_WITH_ARIA_128_GCM_SHA256
xc052 DHE-RSA-ARIA128-GCM-SHA256 DH 2048 ARIAGCM 128 TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256
xc060 ECDHE-ARIA128-GCM-SHA256 ECDH 521 ARIAGCM 128 TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256
TLSv1.3 (no server order, thus listed by strength)
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
Has server cipher order? no (NOT ok)
(limited sense as client will pick)
Testing robust forward secrecy (FS) -- omitting Null Authentication/Encryption, 3DES, RC4
FS is offered (OK) , ciphers follow (client/browser support is important here)
Hexcode Cipher Suite Name (OpenSSL) KeyExch. Encryption Bits Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 521 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
xc028 ECDHE-RSA-AES256-SHA384 ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
xc014 ECDHE-RSA-AES256-SHA ECDH 521 AES 256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
x9f DHE-RSA-AES256-GCM-SHA384 DH 2048 AESGCM 256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 521 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xccaa DHE-RSA-CHACHA20-POLY1305 DH 2048 ChaCha20 256 TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xc0a3 DHE-RSA-AES256-CCM8 DH 2048 AESCCM8 256 TLS_DHE_RSA_WITH_AES_256_CCM_8
xc09f DHE-RSA-AES256-CCM DH 2048 AESCCM 256 TLS_DHE_RSA_WITH_AES_256_CCM
x6b DHE-RSA-AES256-SHA256 DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
x39 DHE-RSA-AES256-SHA DH 2048 AES 256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA
xc077 ECDHE-RSA-CAMELLIA256-SHA384 ECDH 521 Camellia 256 TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384
xc4 DHE-RSA-CAMELLIA256-SHA256 DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256
x88 DHE-RSA-CAMELLIA256-SHA DH 2048 Camellia 256 TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA
xc053 DHE-RSA-ARIA256-GCM-SHA384 DH 2048 ARIAGCM 256 TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384
xc061 ECDHE-ARIA256-GCM-SHA384 ECDH 521 ARIAGCM 256 TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 521 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
xc027 ECDHE-RSA-AES128-SHA256 ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
xc013 ECDHE-RSA-AES128-SHA ECDH 521 AES 128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
x9e DHE-RSA-AES128-GCM-SHA256 DH 2048 AESGCM 128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
xc0a2 DHE-RSA-AES128-CCM8 DH 2048 AESCCM8 128 TLS_DHE_RSA_WITH_AES_128_CCM_8
xc09e DHE-RSA-AES128-CCM DH 2048 AESCCM 128 TLS_DHE_RSA_WITH_AES_128_CCM
x67 DHE-RSA-AES128-SHA256 DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
x33 DHE-RSA-AES128-SHA DH 2048 AES 128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA
xc076 ECDHE-RSA-CAMELLIA128-SHA256 ECDH 521 Camellia 128 TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
xbe DHE-RSA-CAMELLIA128-SHA256 DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256
x45 DHE-RSA-CAMELLIA128-SHA DH 2048 Camellia 128 TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA
xc052 DHE-RSA-ARIA128-GCM-SHA256 DH 2048 ARIAGCM 128 TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256
xc060 ECDHE-ARIA128-GCM-SHA256 ECDH 521 ARIAGCM 128 TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256
KEMs offered None
Elliptic curves offered: prime256v1 secp384r1 secp521r1 X25519 X448
Finite field group: ffdhe2048 ffdhe3072 ffdhe4096 ffdhe6144 ffdhe8192
TLS 1.2 sig_algs offered: RSA-PSS-RSAE+SHA512 RSA-PSS-RSAE+SHA384 RSA-PSS-RSAE+SHA256 RSA+SHA512 RSA+SHA384 RSA+SHA256 RSA+SHA224
TLS 1.3 sig_algs offered: RSA-PSS-RSAE+SHA512 RSA-PSS-RSAE+SHA384 RSA-PSS-RSAE+SHA256
Testing server defaults (Server Hello)
TLS extensions "server name/#0" "max fragment length/#1" "supported_groups/#10" "EC point formats/#11" "application layer protocol negotiation/#16" "encrypt-then-mac/#22" "extended master secret/#23" "session ticket/#35" "supported versions/#43" "key share/#51" "renegotiation info/#65281"
Session Ticket RFC 5077 hint 300 seconds, session tickets keys seems to be rotated < daily
SSL Session ID support yes
Session Resumption tickets: yes, ID: yes
TLS 1.3 early data support no early data offered
TLS clock skew Random values, no fingerprinting possible
Certificate Compression none
Client Authentication none
Signature Algorithm SHA256 with RSA
Server key size RSA 2048 bits (exponent is 65537)
Server key usage --
Server extended key usage --
Serial 097DCD41CA874227BA1F8427DB1020E33582ED5B (OK: length 20)
Fingerprints SHA1 227AC7A42A00EC30E5A771721D0DCF6921EEBC6B
SHA256 6366F3F8D7187C5161F4DCB75E0582D5F78059A52602863006CD6E23112E6E6A
Common Name (CN) www.probas2.example (CN in response to request w/o SNI: server-https.platega.example )
subjectAltName (SAN) missing (NOT ok) -- Browsers are complaining
Trust (hostname) via CN only -- Browsers are complaining (w/o SNI: certificate does not match supplied URI)
Chain of trust NOT ok (self signed)
EV cert (experimental) no
Certificate Validity (UTC) 364 >= 60 days (2026-02-07 21:50 --> 2027-02-07 21:50)
ETS/"eTLS", visibility info not present
Certificate Revocation List --
Running client simulations (HTTP) via sockets
Browser Protocol Cipher Suite Name (OpenSSL) Forward Secrecy
------------------------------------------------------------------------------------------------
Android 7.0 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 256 bit ECDH (P-256)
Android 8.1 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 253 bit ECDH (X25519)
Android 9.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 10.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 11/12 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 13/14 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 15 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Chrome 101 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Chromium 137 (Win 11) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Firefox 100 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Firefox 137 (Win 11) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
IE 8 Win 7 No connection
IE 11 Win 7 TLSv1.2 ECDHE-RSA-AES256-SHA384 256 bit ECDH (P-256)
IE 11 Win 8.1 TLSv1.2 ECDHE-RSA-AES256-SHA384 256 bit ECDH (P-256)
IE 11 Win Phone 8.1 TLSv1.2 AES128-SHA256 No FS
IE 11 Win 10 TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
Edge 15 Win 10 TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 253 bit ECDH (X25519)
Edge 101 Win 10 21H2 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Edge 133 Win 11 23H2 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 18.4 (iOS 18.4) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 15.4 (macOS 12.3.1) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 18.4 (macOS 15.4) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Java 7u25 No connection
Java 8u442 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Java 11.0.2 (OpenJDK) TLSv1.3 TLS_AES_128_GCM_SHA256 256 bit ECDH (P-256)
Java 17.0.3 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Java 21.0.6 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
go 1.17.8 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
LibreSSL 3.3.6 (macOS) TLSv1.3 TLS_CHACHA20_POLY1305_SHA256 253 bit ECDH (X25519)
OpenSSL 1.0.2e TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
OpenSSL 1.1.1d (Debian) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
OpenSSL 3.0.15 (Debian) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
OpenSSL 3.5.0 (git) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Apple Mail (16.0) TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
Thunderbird (91.9) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Rating (experimental)
Rating specs (not complete) SSL Labs's 'SSL Server Rating Guide' (version 2009r from 2025-05-16)
Specification documentation https://github.com/ssllabs/research/wiki/SSL-Server-Rating-Guide
Protocol Support (weighted) 0 (0)
Key Exchange (weighted) 0 (0)
Cipher Strength (weighted) 0 (0)
Final Score 0
Overall Grade T
Grade cap reasons Grade capped to T. Issues with chain of trust (self signed)
Done 2026-02-07 23:02:56 [ 203s] -->> 192.0.2.13:443 (www.probas2.example) <<--
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Done testing now all IP addresses (on port 443): 192.0.2.13
OCSP URI --
NOT ok -- neither CRL nor OCSP URI provided
OCSP stapling not offered
OCSP must staple extension --
DNS CAA RR (experimental) not offered
Certificate Transparency --
Certificates provided 1
Issuer www.probas2.example (probas2 from ES)
Intermediate Bad OCSP (exp.) Ok
Testing HTTP header response @ "/"
HTTP Status Code 200 OK
HTTP clock skew 0 sec from localtime
Strict Transport Security not offered
Public Key Pinning --
Server banner Apache/2.4.52 (Ubuntu)
Application banner --
Cookie(s) (none issued at "/")
Security headers --
Reverse Proxy banner --
Testing vulnerabilities
Heartbleed (CVE-2014-0160) not vulnerable (OK), no heartbeat extension
CCS (CVE-2014-0224) not vulnerable (OK)
Ticketbleed (CVE-2016-9244), experiment. not vulnerable (OK)
Opossum (CVE-2025-49812) not vulnerable (OK)
ROBOT not vulnerable (OK)
Secure Renegotiation (RFC 5746) supported (OK)
Secure Client-Initiated Renegotiation not vulnerable (OK)
CRIME, TLS (CVE-2012-4929) not vulnerable (OK)
BREACH (CVE-2013-3587) potentially NOT ok, "gzip" HTTP compression detected. - only supplied "/" tested
Can be ignored for static pages or if no secrets in the page
POODLE, SSL (CVE-2014-3566) not vulnerable (OK), no SSLv3 support
TLS_FALLBACK_SCSV (RFC 7507) No fallback possible (OK), no protocol below TLS 1.2 offered
SWEET32 (CVE-2016-2183, CVE-2016-6329) not vulnerable (OK)
FREAK (CVE-2015-0204) not vulnerable (OK)
DROWN (CVE-2016-0800, CVE-2016-0703) not vulnerable on this host and port (OK)
make sure you don't use this certificate elsewhere with SSLv2 enabled services, see
https://search.censys.io/search?resource=hosts&virtual_hosts=INCLUDE&q=6366F3F8D7187C5161F4DCB75E0582D5F78059A52602863006CD6E23112E6E6A
LOGJAM (CVE-2015-4000), experimental common prime with 2048 bits detected: RFC3526/Oakley Group 14 (2048 bits),
but no DH EXPORT ciphers
BEAST (CVE-2011-3389) not vulnerable (OK), no SSL3 or TLS1
LUCKY13 (CVE-2013-0169), experimental potentially VULNERABLE, uses cipher block chaining (CBC) ciphers with TLS. Check patches
Winshock (CVE-2014-6321), experimental not vulnerable (OK)
RC4 (CVE-2013-2566, CVE-2015-2808) no RC4 ciphers detected (OK)
Podemos ver que o server pode traballar con TLS1.2 e TLS1.3, que aparecen varios "Not ok" relacionados cos protocolos de cifrado ofrecidos e co noso certificado autoasinado e que podemos ser vulnerables a BREACH (CVE-2013-3587) e LUCKY13 (CVE-2013-0169). Nos acometeremos a fortificación das comunicacións https asignando ás seguintes directivas os valores recomendados para impedir ou mitigar os ataques anteriores:
SSLCompression: permite habilitar a compresión de datos no nivel SSL/TLS. O ataque CRIME emprega a compresión a nivel SSL polo que haberá que configurar a directiva a off. SSLProtocol: permite controlar que versións de SSL/TLS usaranse. Aínda que os posibles valores desta directiva aparecen na seguinte táboa débese deshabilitar SSLv2 e SSLv3. SSLv2 SSL versión 2.0 SSLv3 SSL versión 3.0 TLSv1 TLS v1.0 TLSv1.1 revisión de TLSv1.0 definido en RFC 4346 (con openssl 1.0.1 ou posterior) TLSv1.2 revisión de TLSv1.1 definido en RFC 5246 (con openssl 1.0.1 ou posterior) TLSv1.3 revisión de TLSv1.2 definido en RFC 8446 (con openssl 1.0.1 ou posterior) All representa '+SSLv3 +TLSv1' ou se usamos opensssl 1.0.1 ou posterior '+SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2' SSLHonorCipherOrder: permite indicar se as preferencias do servidor prevalecen sobre as do cliente no establecemento da canle SSL/TLS. Cando se escolle un cifrado durante a negociación SSL/TLS, normalmente as preferencias do cliente son usadas (valor off); sen embargo, o recomendado é que teñan prioridade as do servidor (valor on).
SSLCipherSuite permite indicar as especificacións de cifrado que se permiten usar ó cliente.
Imos modificar o arquivo de configuración do módulo ssl de apache para que os novos valores destas directivas afecten a todos os sitios web do servidor Apache e recollan os valores recomendados polo equipo de seguridade de Mozilla.
No exemplo escollesmos unha configuración intermedia: https://mozilla.github.io/server-side-tls/ssl-config-generator/
$ dpkg -l | grep -i apache2
ii apache2 2.4.52-1ubuntu4.18 amd64 Apache HTTP Server ...
$ dpkg -l | grep -i openssl
ii openssl 3.0.2-0ubuntu1.21 amd64 Secure Sockets Layer toolkit - cryptographic utility ...
Mozilla SSL Configuration Generator
Fig. Mozilla SSL Configuration Generator
Editamos a configuración engadindo as recomendación de Mozilla (comentando as directivas con valores vellos xa presentes como SSLProtocol e SSLCipherSuite por exemplo)
$ sudo nano /etc/apache2/mods-available/ssl.conf
... # intermediate configuration SSLProtocol all -SSLv3 -TLSv1 -TLSv1.1 SSLCipherSuite ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305 SSLHonorCipherOrder off SSLSessionTickets off SSLUseStapling On SSLStaplingCache "shmcb:logs/ssl_stapling(32768)"
$ sudo systemctl restart apache2
Lanzamos novamente a análise e vemos que xa non se ofertan todos os protocolos SSL/TLS e que ademasi arranxáronse algunhas das advertencias:
~/testssl.sh $ ./testssl.sh --wide https://www.probas2.example
#####################################################################
testssl.sh version 3.3dev from https://testssl.sh/dev/
(79db276 2026-01-15 15:19:45)
This program is free software. Distribution and modification under
GPLv2 permitted. USAGE w/o ANY WARRANTY. USE IT AT YOUR OWN RISK!
Please file bugs @ https://testssl.sh/bugs/
#####################################################################
Using OpenSSL 1.0.2-bad (Mar 28 2025) [~179 ciphers]
on incus:./bin/openssl.Linux.x86_64
Testing all IPv4 addresses (port 443): 192.0.2.13
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Start 2026-02-07 23:15:19 -->> 192.0.2.13:443 (www.probas2.example) <<--
A record via: /etc/hosts
rDNS (192.0.2.13): www.probas1.example. www.probas2.example. www.probas3.example.
Service detected: HTTP
Testing protocols via sockets except NPN+ALPN
SSLv2 not offered (OK)
SSLv3 not offered (OK)
TLS 1 not offered
TLS 1.1 not offered
TLS 1.2 offered (OK)
TLS 1.3 offered (OK): final
QUIC Local problem: No OpenSSL QUIC support
NPN/SPDY not offered
ALPN/HTTP2 http/1.1 (offered)
Testing cipher categories
NULL ciphers (no encryption) not offered (OK)
Anonymous NULL Ciphers (no authentication) not offered (OK)
Export ciphers (w/o ADH+NULL) not offered (OK)
LOW: 64 Bit + DES, RC[2,4], MD5 (w/o export) not offered (OK)
Triple DES Ciphers / IDEA not offered
Obsoleted CBC ciphers (AES, ARIA etc.) not offered
Strong encryption (AEAD ciphers) with no FS not offered
Forward Secrecy strong encryption (AEAD ciphers) offered (OK)
Testing server's cipher preferences
Hexcode Cipher Suite Name (OpenSSL) KeyExch. Encryption Bits Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
SSLv2
-
SSLv3
-
TLSv1
-
TLSv1.1
-
TLSv1.2 (no server order, thus listed by strength)
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 384 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
x9f DHE-RSA-AES256-GCM-SHA384 DH 2048 AESGCM 256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 384 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xccaa DHE-RSA-CHACHA20-POLY1305 DH 2048 ChaCha20 256 TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 384 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
x9e DHE-RSA-AES128-GCM-SHA256 DH 2048 AESGCM 128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
TLSv1.3 (no server order, thus listed by strength)
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
Has server cipher order? no
(limited sense as client will pick)
Testing robust forward secrecy (FS) -- omitting Null Authentication/Encryption, 3DES, RC4
FS is offered (OK) , ciphers follow (client/browser support is important here)
Hexcode Cipher Suite Name (OpenSSL) KeyExch. Encryption Bits Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
x1302 TLS_AES_256_GCM_SHA384 ECDH 253 AESGCM 256 TLS_AES_256_GCM_SHA384
x1303 TLS_CHACHA20_POLY1305_SHA256 ECDH 253 ChaCha20 256 TLS_CHACHA20_POLY1305_SHA256
xc030 ECDHE-RSA-AES256-GCM-SHA384 ECDH 384 AESGCM 256 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
x9f DHE-RSA-AES256-GCM-SHA384 DH 2048 AESGCM 256 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
xcca8 ECDHE-RSA-CHACHA20-POLY1305 ECDH 384 ChaCha20 256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
xccaa DHE-RSA-CHACHA20-POLY1305 DH 2048 ChaCha20 256 TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
x1301 TLS_AES_128_GCM_SHA256 ECDH 253 AESGCM 128 TLS_AES_128_GCM_SHA256
xc02f ECDHE-RSA-AES128-GCM-SHA256 ECDH 384 AESGCM 128 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
x9e DHE-RSA-AES128-GCM-SHA256 DH 2048 AESGCM 128 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
KEMs offered None
Elliptic curves offered: prime256v1 secp384r1 X25519
DH group offered: RFC3526/Oakley Group 14 (2048 bits)
TLS 1.2 sig_algs offered: RSA-PSS-RSAE+SHA512 RSA-PSS-RSAE+SHA384 RSA-PSS-RSAE+SHA256 RSA+SHA512 RSA+SHA384 RSA+SHA256 RSA+SHA224
TLS 1.3 sig_algs offered: RSA-PSS-RSAE+SHA512 RSA-PSS-RSAE+SHA384 RSA-PSS-RSAE+SHA256
Testing server defaults (Server Hello)
TLS extensions "server name/#0" "max fragment length/#1" "supported_groups/#10" "EC point formats/#11" "application layer protocol negotiation/#16" "extended master secret/#23" "supported versions/#43" "key share/#51" "renegotiation info/#65281"
Session Ticket RFC 5077 hint no -- no lifetime advertised
SSL Session ID support yes
Session Resumption tickets no, ID: yes
TLS 1.3 early data support no early data offered
TLS clock skew Random values, no fingerprinting possible
Certificate Compression none
Client Authentication none
Signature Algorithm SHA256 with RSA
Server key size RSA 2048 bits (exponent is 65537)
Server key usage --
Server extended key usage --
Serial 097DCD41CA874227BA1F8427DB1020E33582ED5B (OK: length 20)
Fingerprints SHA1 227AC7A42A00EC30E5A771721D0DCF6921EEBC6B
SHA256 6366F3F8D7187C5161F4DCB75E0582D5F78059A52602863006CD6E23112E6E6A
Common Name (CN) www.probas2.example (CN in response to request w/o SNI: server-https.platega.example )
subjectAltName (SAN) missing (NOT ok) -- Browsers are complaining
Trust (hostname) via CN only -- Browsers are complaining (w/o SNI: certificate does not match supplied URI)
Chain of trust NOT ok (self signed)
EV cert (experimental) no
Certificate Validity (UTC) 364 >= 60 days (2026-02-07 21:50 --> 2027-02-07 21:50)
ETS/"eTLS", visibility info not present
Certificate Revocation List --
OCSP URI --
NOT ok -- neither CRL nor OCSP URI provided
OCSP stapling not offered
OCSP must staple extension --
DNS CAA RR (experimental) not offered
Certificate Transparency --
Certificates provided 1
Issuer www.probas2.example (probas2 from ES)
Intermediate Bad OCSP (exp.) Ok
Testing HTTP header response @ "/"
HTTP Status Code 200 OK
HTTP clock skew 0 sec from localtime
Strict Transport Security not offered
Public Key Pinning --
Server banner Apache/2.4.52 (Ubuntu)
Application banner --
Cookie(s) (none issued at "/")
Security headers --
Reverse Proxy banner --
Testing vulnerabilities
Heartbleed (CVE-2014-0160) not vulnerable (OK), no heartbeat extension
CCS (CVE-2014-0224) not vulnerable (OK)
Ticketbleed (CVE-2016-9244), experiment. not vulnerable (OK), no session ticket extension
Opossum (CVE-2025-49812) not vulnerable (OK)
ROBOT Server does not support any cipher suites that use RSA key transport
Secure Renegotiation (RFC 5746) supported (OK)
Secure Client-Initiated Renegotiation not vulnerable (OK)
CRIME, TLS (CVE-2012-4929) not vulnerable (OK)
BREACH (CVE-2013-3587) potentially NOT ok, "gzip" HTTP compression detected. - only supplied "/" tested
Can be ignored for static pages or if no secrets in the page
POODLE, SSL (CVE-2014-3566) not vulnerable (OK), no SSLv3 support
TLS_FALLBACK_SCSV (RFC 7507) No fallback possible (OK), no protocol below TLS 1.2 offered
SWEET32 (CVE-2016-2183, CVE-2016-6329) not vulnerable (OK)
FREAK (CVE-2015-0204) not vulnerable (OK)
DROWN (CVE-2016-0800, CVE-2016-0703) not vulnerable on this host and port (OK)
make sure you don't use this certificate elsewhere with SSLv2 enabled services, see
https://search.censys.io/search?resource=hosts&virtual_hosts=INCLUDE&q=6366F3F8D7187C5161F4DCB75E0582D5F78059A52602863006CD6E23112E6E6A
LOGJAM (CVE-2015-4000), experimental common prime with 2048 bits detected: RFC3526/Oakley Group 14 (2048 bits),
but no DH EXPORT ciphers
BEAST (CVE-2011-3389) not vulnerable (OK), no SSL3 or TLS1
LUCKY13 (CVE-2013-0169), experimental not vulnerable (OK)
Winshock (CVE-2014-6321), experimental not vulnerable (OK)
RC4 (CVE-2013-2566, CVE-2015-2808) no RC4 ciphers detected (OK)
Running client simulations (HTTP) via sockets
Browser Protocol Cipher Suite Name (OpenSSL) Forward Secrecy
------------------------------------------------------------------------------------------------
Android 7.0 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 256 bit ECDH (P-256)
Android 8.1 (native) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 253 bit ECDH (X25519)
Android 9.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 10.0 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 11/12 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 13/14 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Android 15 (native) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Chrome 101 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Chromium 137 (Win 11) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Firefox 100 (Win 10) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Firefox 137 (Win 11) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
IE 8 Win 7 No connection
IE 11 Win 7 TLSv1.2 DHE-RSA-AES256-GCM-SHA384 2048 bit DH
IE 11 Win 8.1 TLSv1.2 DHE-RSA-AES256-GCM-SHA384 2048 bit DH
IE 11 Win Phone 8.1 No connection
IE 11 Win 10 TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
Edge 15 Win 10 TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 253 bit ECDH (X25519)
Edge 101 Win 10 21H2 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Edge 133 Win 11 23H2 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 18.4 (iOS 18.4) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 15.4 (macOS 12.3.1) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Safari 18.4 (macOS 15.4) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Java 7u25 No connection
Java 8u442 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Java 11.0.2 (OpenJDK) TLSv1.3 TLS_AES_128_GCM_SHA256 256 bit ECDH (P-256)
Java 17.0.3 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Java 21.0.6 (OpenJDK) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
go 1.17.8 TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
LibreSSL 3.3.6 (macOS) TLSv1.3 TLS_CHACHA20_POLY1305_SHA256 253 bit ECDH (X25519)
OpenSSL 1.0.2e TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
OpenSSL 1.1.1d (Debian) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
OpenSSL 3.0.15 (Debian) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
OpenSSL 3.5.0 (git) TLSv1.3 TLS_AES_256_GCM_SHA384 253 bit ECDH (X25519)
Apple Mail (16.0) TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256 bit ECDH (P-256)
Thunderbird (91.9) TLSv1.3 TLS_AES_128_GCM_SHA256 253 bit ECDH (X25519)
Rating (experimental)
Rating specs (not complete) SSL Labs's 'SSL Server Rating Guide' (version 2009r from 2025-05-16)
Specification documentation https://github.com/ssllabs/research/wiki/SSL-Server-Rating-Guide
Protocol Support (weighted) 0 (0)
Key Exchange (weighted) 0 (0)
Cipher Strength (weighted) 0 (0)
Final Score 0
Overall Grade T
Grade cap reasons Grade capped to T. Issues with chain of trust (self signed)
Done 2026-02-07 23:17:37 [ 146s] -->> 192.0.2.13:443 (www.probas2.example) <<--
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Done testing now all IP addresses (on port 443): 192.0.2.13
Con esta nova configuración, xa non hai avisos relacionados con Lucky13 por exemplo. Habería que ir probando configuracións ata acadar o nivel desexado, tendo en conta que limitar o tipo de SSL/TLS a usar pode provocar que certos navegadores teñan problemas ó acceder por https, sobre todo si se trata de versións vellas.
nmap
Nmap xa foi utilizado no Escenario 4A para facer barridos de portos e detección de servizos. NSE (Nmap Scripting Engine) permite ampliar a potencia e versatilidade de nmap xa que, a través de scripts, permite automatizar unha gran variedade de tarefas de rede: exploracións de rede, detección avanzada de servizos, detección e explotación de vulnerabilidades, detección de portas traseiras/backdoors, ..., habendo centos de scripts. Por exemplo, no seu día publicouse unha versión do servidor FTP vsftpd cunha porta traseira e esta vulnerabilidade podémola descubrir lanzado o script NSE ftp-vsftpd-backdoor:
$ sudo nmap --script ftp-vsftpd-backdoor -p 21 192.168.1.47
Starting Nmap 7.01 ( https://nmap.org ) at 2017-11-12 02:06 CET Nmap scan report for 192.168.1.47 Host is up (0.00028s latency). PORT STATE SERVICE 21/tcp open ftp | ftp-vsftpd-backdoor: | VULNERABLE: | vsFTPd version 2.3.4 backdoor | State: VULNERABLE (Exploitable) | IDs: CVE:CVE-2011-2523 OSVDB:73573 | vsFTPd version 2.3.4 backdoor, this was reported on 2011-07-04. | Disclosure date: 2011-07-03 | Exploit results: | Shell command: id | Results: uid=0(root) gid=0(root) | References: | http://osvdb.org/73573 | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/unix/ftp/vsftpd_234_backdoor.rb | http://scarybeastsecurity.blogspot.com/2011/07/alert-vsftpd-download-backdoored.html |_ https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-2523 MAC Address: 08:00:27:CF:70:13 (Oracle VirtualBox virtual NIC) Nmap done: 1 IP address (1 host up) scanned in 1.79 seconds
Usando o script ssl-enum-ciphers podemos facer un estudo do estado do SSL/TLS no noso servidor e co plugin ssl-cert podemos ver a infomación do certificado do sitio:
$ nmap -Pn -sV --script ssl-cert,ssl-enum-ciphers -p 443 www.probas2.example
Starting Nmap 7.94SVN ( https://nmap.org ) at 2026-02-07 23:22 CET Nmap scan report for www.probas2.example (192.0.2.13) Host is up (0.000063s latency). rDNS record for 192.0.2.13: www.probas1.example PORT STATE SERVICE VERSION 443/tcp open ssl/http Apache httpd 2.4.52 | ssl-enum-ciphers: | TLSv1.2: | ciphers: | TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A | TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (dh 2048) - A | TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A | TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (secp256r1) - A | compressors: | NULL | cipher preference: client | TLSv1.3: | ciphers: | TLS_AKE_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A | TLS_AKE_WITH_AES_256_GCM_SHA384 (ecdh_x25519) - A | TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (ecdh_x25519) - A | cipher preference: client |_ least strength: A |_http-server-header: Apache/2.4.52 (Ubuntu) | ssl-cert: Subject: commonName=www.probas2.example/organizationName=probas2/stateOrProvinceName=Spain/countryName=ES | Issuer: commonName=www.probas2.example/organizationName=probas2/stateOrProvinceName=Spain/countryName=ES | Public Key type: rsa | Public Key bits: 2048 | Signature Algorithm: sha256WithRSAEncryption | Not valid before: 2026-02-07T21:50:30 | Not valid after: 2027-02-07T21:50:30 | MD5: 0adb:9608:da74:1d98:340c:32ed:be43:dad0 |_SHA-1: 227a:c7a4:2a00:ec30:e5a7:7172:1d0d:cf69:21ee:bc6b MAC Address: 10:66:6A:84:39:02 (Unknown) Service Info: Host: server-https Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 13.05 seconds
En anos anteriores unha análise dun servidor Apache recén instalado e coa configuración por defecto daba dous avisos:
- Aviso asociado a SSLv3 relativo á incidencia CVE-2014-3566 (ataque POODLE); polo que e tras revisar a información sobre a vulnerabilidade, desaconséllase desactivar SSLv3.
- Aviso en TLSv1.1 e TLSv1.2 onde se indica que o algoritmo de cifrado RC4 (empregado para mitigar o ataque BEAST) xa non é necesario e non se aconsella o seu uso.
$ nmap -Pn -sV --script ssl-enum-ciphers -p 443 www.probas2.com
Starting Nmap 7.01 ( https://nmap.org ) at 2017-11-13 14:59 CET Nmap scan report for www.probas2.com (192.168.1.254) Host is up (0.00052s latency). rDNS record for 192.168.1.254: www.probas1.com PORT STATE SERVICE VERSION 443/tcp open ssl/http Apache httpd 2.4.7 |_http-server-header: Apache/2.4.7 (Ubuntu) | ssl-enum-ciphers: | SSLv3: | ciphers: | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C | TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A | TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A | TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C | TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A | TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A | compressors: | NULL | cipher preference: client | warnings: | CBC-mode cipher in SSLv3 (CVE-2014-3566) | TLSv1.0: | ciphers: | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C | TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A | TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A | TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C | TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A | TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A | compressors: | NULL | cipher preference: client | TLSv1.1: | ciphers: | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C | TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A | TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A | TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C | TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A | TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A | compressors: | NULL | cipher preference: client | warnings: | Weak cipher RC4 in TLSv1.1 or newer not needed for BEAST mitigation | TLSv1.2: | ciphers: | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (dh 2048) - C | TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 2048) - A | TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 2048) - A | TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A | TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 2048) - A | TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (secp256r1) - C | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A | TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A | TLS_ECDHE_RSA_WITH_RC4_128_SHA (secp256r1) - A | TLS_RSA_WITH_3DES_EDE_CBC_SHA (rsa 2048) - C | TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A | TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A | TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A | TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A | TLS_RSA_WITH_RC4_128_SHA (rsa 2048) - A | TLS_RSA_WITH_SEED_CBC_SHA (rsa 2048) - A | compressors: | NULL | cipher preference: client | warnings: | Weak cipher RC4 in TLSv1.1 or newer not needed for BEAST mitigation |_ least strength: C Service Info: Host: bogus_host_without_reverse_dns Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 13.08 seconds
Uso de ferramentas
O uso de ferramentas é moi interesante xa que axuda ós administradores na labor de localizar vulnerabilidades ou configuracións non seguras. Algunhas moi coñecidas son:
- testssl
- nmap
- NSE
- sslscan
- Nessus
É tarefa dos administradores revisar a información dispoñible sobre os servidores que xestionan para configuralos da forma máis robusta posible ó tempo que proporcionan os servizos esperados.
