quinta-feira, 10 de novembro de 2011

Detectando Máquinas que fazem parte da rede Rustock

Recentemente fomos notificados que possíveis máquinas da nossa rede estaria fazendo parte da rede de botnets Rustock (1). Pesquisei pelo Google e encontrei a lista de IP's dos servidores da rede Rustock.

A lista você encontra no link abaixo:

Rustock CnC Servers: http://blog.fireeye.com/research/rustock-cnc-servers.html

Usando o tcpdump pude filtrar todo tráfego com destino aos IP's e salvar o resultado em um arquivo para que posteriormente possa ser analisado, veja o script como ficou:

#!/bin/bash 
tcpdump -nn -i any host 173.192.135.102 or host 173.192.135.98 \
or host 173.192.135.99 or host 173.208.128.50 or host 173.208.128.74 \
or host 173.208.128.82 or host 173.208.131.178 or host 173.208.131.98 \
or host 173.208.141.154 or host 173.208.143.114 or host 173.208.143.122 \
or host 173.208.143.194 or host 173.208.143.90 or host 173.208.150.90 \
or host 173.208.154.90 or host 173.208.162.2 or host 173.208.163.178 \
or host 173.208.163.242 or host 173.212.214.194 or host 173.212.241.42 or host 173.212.241.50 or host 173.212.243.114 \
or host 173.83.26.26 or host 173.83.26.34 or host 174.139.250.66 or host 174.36.237.84 or host 204.12.192.250 \
or host 204.12.217.218 or host 204.12.217.250 or host 204.12.217.42 or host 204.12.217.98 or host 204.12.220.122 \
or host 204.12.237.202 or host 204.12.243.210 or host 204.12.243.34 or host 204.12.243.42 or host 204.12.243.58 \
or host 204.12.248.66 or host 204.45.118.202 or host 204.45.118.250 or host 204.45.119.10 or host 204.45.119.18 \
or host 204.45.119.2 or host 204.45.119.26 or host 204.45.119.34 or host 204.45.119.42 or host 204.45.119.50 \
or host 204.45.119.74 or host 204.45.119.82 or host 204.45.119.90 or host 204.45.121.130 or host 204.45.121.18 \
or host 204.45.121.34 or host 204.45.121.42 or host 204.45.121.50 or host 204.45.121.58 or host 206.217.206.8 \
or host 208.101.27.108 or host 208.101.27.44 or host 208.101.27.72 or host 208.110.71.58 or host 208.110.80.50 \
or host 208.110.82.186 or host 208.43.102.220 or host 208.43.157.96 or host 208.43.17.44 or host 208.43.18.12 \
or host 208.43.31.8 or host 208.43.40.148 or host 64.120.144.69 or host 64.120.149.117 or host 64.120.153.117 \
or host 64.191.18.149 or host 64.191.38.165 or host 64.191.53.37 or host 64.191.59.245 or host 64.22.109.222 \
or host 66.197.161.181 or host 66.197.251.69 or host 66.79.162.138 or host 66.79.162.86 or host 66.79.163.102 \
or host 66.96.214.53 or host 66.96.224.213 or host 67.228.206.92 or host 69.197.144.138 or host 69.197.158.242 \
or host 69.197.158.250 or host 69.197.161.34 or host 69.50.197.191 or host 72.26.196.194 or host 74.86.210.133 \
or host 74.86.210.134 or host 76.164.194.226 or host 85.17.200.13 or host 95.211.128.25 or host 96.0.203.106 \
or host 96.0.203.114 or host 96.0.203.122 or host 96.0.203.82 or host 96.0.203.90 or host 96.0.203.98 or host 96.31.81.44 \
or host 96.45.189.178 or host 96.9.169.53 or host 96.9.180.21 or host 96.9.182.101 or host 96.9.182.197 or host 96.9.183.149 \
or host 98.126.114.50 or host 98.126.42.26 or host 98.126.76.186 or host 98.126.77.2 or host 98.141.220.194 \
or host 98.141.220.226 -w /var/log/rustock.log &

O resultado será salvo no arquivo /var/log/rustock.log. Para ler este arquivo temos que usar o tcpdump e redirecionar a saída para um arquivo:

#tcpdump -r /var/log/rustock.log > /tmp/rustock.txt

Agora já podemos manipular as informações. Dando um cat no arquivo veja o que temos:

13:40:32.613458 IP 10.123.122.254.1436 > ..www: Flags [S], seq 3547421019, win 65535, options [mss 1460,nop,nop,sackOK], length 0

Precisamos filtrar o arquivo para termos só o que nos interessa, o IP. Para isso execute o comando abaixo:

#cat /tmp/rustock.txt | cut -f3 -d" " | cut -f1-4 -d.

Agora temos a lista dos IP's que estão tentando se conectar em um dos servidores do Rustock. Agora vamos usar o comando sort para que não apareça os IP's repetidos:

#cat /tmp/rustock.txt | cut -f3 -d" " | cut -f1-4 -d. | sort -u

Agora temos a lista dos IP's que deverão ser investigados.



Referencia:

(1) http://pt.scribd.com/doc/59395728/Battling-the-Rustock-Threat

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