Snort y OpenAppID:Bloquear protocolos de capa 7: openvpn,Facebook,twitter

iplost

Ok, probaré con DNSBL

javcasta

Hola

Si pruebas con DNSBL, a parte del dominio bloqueado en un DNSBL feed, también se puede definir en:
Firewall > pfBlockerNG > DNSBL > TLD Blacklist ; facebook.com

Y defines con eso un Top-Level Domain (facebook.com) a bloquear
La redundancia nunca está de más :)

Salu2

iplost

Ok, creo que en el TLD blocklist se pondría solo facebook, lo miro

javcasta

Hola

Sí, en el TLD blacklist del DNSBL se pone el dominio de nivel alto (facebook.com => facebook), pruebalo.

Y por cierto, rectifico, sí me bloquea Facebook (vía navegador y vía App) las reglas de Snort personalizadas, lo que pasa es que en la prueba se me olvidó dejar de navegar vía tunel ssh :) jejeje, despiste (devil is in details :) )

Salu2

iplost

A mi me faltaba una regla de las 3 de FB. Todo ok.

DaLiCaM

Yo tengo Facebook bloqueado con pfBlockerNG, añadiendo una regla en el apartado IPv4, allí añado los ASN de facebook

javcasta

Hola

Yo tengo Facebook bloqueado con pfBlockerNG, añadiendo una regla en el apartado IPv4, allí añado los ASN de facebook

Sí, pfBlockerNG es un paquete que facilita la vida mucho en el tema de bloquear sitios,, ya sea por listas de IP , dominios (DNSBL) y ASN. Es un paquete imprescindible en pfSense :)

Lo que ocurre es que pfSense en sus nuevas versiones abandonó el DPI (Deep packet Inspection and layer 7 filter con ipfw-classifyd ), por su elevado consumo de CPU, y la alternativa para bloquear protocolos de capa 7 o de aplicación es Snort (o Suricata), ellos mismos lo dicen en:

https://doc.pfsense.org/index.php/Layer_7

_Layer 7 filtering or shaping is identifying traffic at layer 7 (Application Layer) of the OSI model.

pfSense used to contain a Layer 7 classifier, ipfw-classifyd, but it has been removed. It was non-functional on pfSense 2.2.x and removed entirely from pfSense 2.3 because it was not feasible to fix. L7 classification consumed large amounts of CPU and rarely had the intended effect, and it was a rarely used feature even when it did function.

For those intending to block based on L7 identification, consider using Snort instead, which can much more efficiently identify such traffic.

Alternate L7 inspection methods may be considered for a future version if they are viable._

Salu2

javcasta

Hola

Un buen ejemplo de reglas personalizadas de Snort, para bloquear Ultrasurf

https://forum.pfsense.org/index.php?topic=48482.msg295806#msg295806


# Rules by Jorge Talamas
alert udp $HOME_NET any -> any 53 (msg:"DNS Request for www.hfdxjshm.info"; content:"|03|www|08|hfdxjshm|04|info"; metadata:service dns; nocase; classtype:policy-violation; sid:1232313; rev:1;)
alert udp $HOME_NET any -> any 53 (msg:"DNS Request for www.rvzjon.info"; content:"|03|www|06|rvzjon|04|info"; metadata:service dns; nocase; classtype:policy-violation; sid:1232314; rev:1;)
alert udp $HOME_NET any -> any 53 (msg:"DNS Request for www.ukwprf.info"; content:"|03|www|06|ukwprf|04|info"; metadata:service dns; nocase; classtype:policy-violation; sid:1232315; rev:1;)

# Rule by SERPRO-Recife Security Team
alert udp $HOME_NET any -> $EXTERNAL_NET 53 (msg:"Possible External Ultrasurf DNS Query"; content:"|00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|"; classtype:policy-violation; detection_filter:track by_src, count 1, seconds 5; sid:1000059; rev:2;)

# IP POOL by Jorge Talamas
var ULTRASURF_POOL [1.160.0.0/16,1.161.122.228/32,1.162.0.0/16,1.163.233.171/32,1.168.0.0/13,12.48.83.220/32,24.11.192.218/31,36.227.0.15/32,36.227.75.242/32,36.229.197.181/32,36.232.154.1/32,46.22.213.8/32,46.22.214.10/32,46.37.175.62/32,46.37.180.174/32,46.105.135.99/32,46.105.135.123/32,46.105.151.18/32,46.105.224.154/32,58.138.34.200/32,59.104.160.0/19,59.112.0.0/15,59.115.0.0/16,59.121.0.0/16,61.31.128.0/19,61.62.0.0/17,61.62.192.0/18,61.216.0.0/17,61.216.128.0/18,61.223.0.0/16,61.224.0.0/16,61.227.0.0/16,61.228.0.0/16,61.230.0.0/15,63.215.202.0/24,63.223.86.79/32,63.223.100.58/32,63.223.101.44/32,63.223.102.73/32,63.223.103.77/32,63.223.124.119/32,63.226.208.180/31,63.245.209.30/31,64.4.44.80/31,64.25.35.100/31,64.25.35.200/31,64.37.73.8/32,64.120.138.55/32,64.120.206.154/32,64.191.20.238/32,64.191.124.239/32,65.49.2.12/31,65.49.14.0/24,65.175.93.68/32,65.175.93.72/32,65.175.93.76/32,66.201.71.143/32,66.201.71.145/32,66.245.218.2/31,67.19.60.8/31,68.65.210.20/32,68.65.238.190/32,69.61.28.24/32,69.61.28.51/32,69.162.176.238/32,69.162.177.246/32,69.162.177.250/32,69.162.179.250/32,69.162.180.238/32,69.162.180.244/32,69.162.180.250/32,69.162.181.241/32,69.162.181.248/32,69.162.182.250/32,69.162.183.246/32,69.162.185.239/32,69.162.185.247/32,69.162.186.245/32,69.162.187.239/32,69.162.189.240/32,69.162.189.246/32,69.162.190.247/32,69.162.191.248/32,70.32.68.126/31,72.21.194.0/24,72.21.203.148/31,72.21.211.170/31,72.21.214.0/24,72.69.176.100/31,74.80.131.100/32,74.80.152.203/32,74.80.167.179/32,74.80.181.109/32,74.127.24.68/32,74.127.52.39/32,74.127.52.42/32,76.191.99.99/32,76.191.102.131/32,76.191.103.56/32,76.191.105.5/32,76.191.105.20/32,76.191.114.32/32,80.79.125.53/32,91.121.253.92/32,95.143.33.144/32,95.143.33.179/32,96.9.133.170/32,96.9.174.174/32,101.128.162.236/31,111.240.0.0/14,111.248.0.0/13,112.104.0.0/17,112.104.128.0/18,112.104.192.0/19,112.105.64.0/18,112.105.128.0/19,112.105.192.0/18,113.197.194.198/31,114.24.0.0/14,114.36.0.0/14,114.40.0.0/13,118.160.0.0/15,118.165.0.0/16,118.166.0.0/15,118.168.0.0/14,122.118.0.0/16,122.120.0.0/14,122.124.162.0/24,122.125.0.0/16,122.126.0.0/15,123.204.74.103/32,123.204.96.0/19,123.205.224.0/19,124.8.72.25/32,124.9.128.0/17,124.11.53.0/24,124.11.128.0/17,124.12.0.0/17,125.224.0.0/15,125.227.0.0/16,125.229.0.0/16,125.230.0.0/16,125.231.91.188/31,125.232.0.0/15,126.126.189.185/32,128.120.32.96/31,129.59.210.100/31,149.5.113.168/32,173.208.227.209/32,173.212.193.131/32,173.212.193.142/32,173.212.193.156/32,174.24.248.14/31,175.180.64.0/18,175.180.128.0/17,175.181.64.0/18,175.181.128.0/17,175.182.0.0/17,184.26.194.70/31,184.82.51.116/32,184.82.113.169/32,184.82.137.235/32,184.82.145.69/32,184.82.205.136/32,195.43.51.21/32,199.114.216.57/32,199.114.217.39/32,199.114.219.83/32,199.114.219.93/32,199.217.100.54/32,199.217.101.32/32,199.217.101.61/32,199.217.102.49/32,203.67.0.0/19,203.67.116.201/32,203.73.50.4/31,203.73.55.210/31,203.73.192.0/18,205.251.242.164/31,207.195.235.35/32,207.195.235.195/32,208.117.17.239/32,208.117.18.242/32,208.117.19.250/32,208.117.22.249/32,208.117.23.246/32,208.117.26.239/32,208.117.27.241/32,208.117.29.246/32,208.117.29.250/32,208.117.31.240/32,210.64.96.0/19,211.74.96.0/19,211.74.191.68/31,212.69.166.19/32,212.69.169.54/32,212.69.191.38/32,212.69.191.237/32,216.13.11.50/31,216.13.113.50/31,216.15.183.18/32,216.15.183.27/32,216.198.215.3/32,216.198.220.120/32,216.198.220.126/32,218.160.0.0/14,218.165.0.0/16,218.166.0.0/15,218.168.0.0/14,218.173.0.0/16,218.174.0.0/15,219.80.130.234/31,219.84.192.0/18,219.85.128.0/17,220.100.55.208/32,220.129.0.0/16,220.131.0.0/16,220.136.0.0/16,220.138.0.0/16,220.141.0.0/16,220.142.0.0/15]

alert tcp $HOME_NET any -> $ULTRASURF_POOL 443 (msg:"Ultrasurf Connection Detected"; flow:established; classtype:policy-violation; sid:5000000; rev:3;)
alert tcp $HOME_NET any -> $ULTRASURF_POOL 10000 (msg:"Ultrasurf Connection Detected"; flow:established; classtype:policy-violation; sid:5000001; rev:3;)

Salu2

iplost

La pega es que el pool de servidores ultrasurf así en una regla de Snort es estático, lo interesante seria programarlo dinámico, como hace pfBlockerNG

javcasta

Hola

Lo veo dificil en una custom rule, no conozco si Snort permite scripting en sus reglas, (variables si permite)

Salu2

javcasta

Hola

Una cosa que se me ocurre para obtener el pool de servidores Ultrasurf dinamicamente seria:

En el fichero de conf de snort (snort.conf), añadir que incluya otro fichero:

http://manual-snort-org.s3-website-us-east-1.amazonaws.com/node16.html

include

por ejemplo pool-surf-snort.inc

Donde se defina y reescriba la variable ULTRASURF_POOL con la lista actualizada de servidores (esto ya seria tarea de un cron que vía scripting reescriba ese fichero con los valores actualizados, y de esa forma, creo que cada vez que actualice snort se refrescaria)

Pero no lo he testeado, si lo hago aviso :)

Salu2

javcasta

Hola

Pues tras leer en el foro. Parece ser que bloquear en destino Ultrasurf no es muy viable. Ya que usa servidores Google, Amazon, etc, y si bloqueamos esas IPs bloqueamos otros servicios y recursos (Google, Amazon, etc).

Pero he visto unas reglas personalizadas de Snort para bloquear Ultrasurf en origen según el contenido de la petición:

Referencia: https://forum.pfsense.org/index.php?topic=91163.msg515530#msg515530

alert tcp any any -> 192.168.1.254 any (content:"|48 6f 73 74 3a 20 73 75 70 70 6f 72 74 2e 6d 69 63 72 6f 73 6f 66 74 2e 63 6f 6d 3a 34 34 33 0d 0a|"; msg:"ultrasurf14 pacote suportmicrosoft"; dsize:266<>270; gid:120; sid:1509; rev:1;)
alert tcp any any -> 192.168.1.254 any (content:"|47 45 54 20 68 74 74 70 3a 2f 2f 77 77 77 2e 67 6f 6f 67 6c 65 2e 63 6f 6d 2f 20 48 54 54 50 2f 31 2e 31 0d 0a|"; dsize:137<>139; msg:"ultrasurf13_12 pacote google"; gid:120; sid:1510; rev:1;)
alert tcp any any -> 192.168.1.254 any (content:"|36 35 2e 34 39 2e 31 34 2e|"; content:"|34 34 33|"; msg:"ultrasurf10 pacote 65.49.14.0/24:443"; gid:120; sid:1511; rev:1;)

Me rsulta curioso que Ultrasurf use servidores de Google (y con certificados de Google!!!).

¿Es Ultrasurf el TOR particular de Google? :) … a saber

ref: http://www.maravento.com/2014/05/ultrasurf-secuestra-ips-de-google-y.html

Salu2