Re: Possible Bot?

["Nicolas Lin Wee Kuan" <myseclist () gmail com>]

Illegitimate use ? icmp tunneling
--> one of the known tool : ptunnel (http://www.cs.uit.no/~daniels/PingTunnel)

1- Sniff ICMP traffic and check payload's packets
2- Investigate on destination server

Possible countermeasure : deny icmp from lan to internet.

Regards,

2008/5/10, Tony Raboza <tonyraboza () gmail com>:
> Hi,
>
> I saw on our MRTG graph and monitoring tool that a PC on our LAN is
> sending out large ICMP traffic to a public IP address.  Upon checking
> on our Internet gateway, I saw this (output of tcpdump - I purposedly
> changed the IP addresses):
>
> 18:00:02.788023 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): ICMP echo
> request, id 4, seq 59931, length 1480
> 18:00:02.788030 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): icmp
> 18:00:02.798828 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): ICMP echo
> request, id 4, seq 60187, length 1480
> 18:00:02.798841 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): icmp
> 18:00:02.809534 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): ICMP echo
> request, id 4, seq 60443, length 1480
> 18:00:02.809546 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): icmp
> 18:00:02.820274 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): ICMP echo
> request, id 4, seq 60699, length 1480
> 18:00:02.820286 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): icmp
> 18:00:02.831246 IP 1.2.3.4 (LANIP) > 4.5.6.7 (PUBLIC IP): ICMP echo
> request, id 4, seq 60955, length 1480
>
>
> Actually, this happened with this PC before - I had our helpdesk check
> (its on a remote site) it for virus/worms but according to them
> nothing turned up.
>
> I'm thinking this might be a sign that this PC is part of a botnet?
> How can I be certain?  And what kind of botnet/worm exhibit the
> behavior as above?
>
> Thank you very much.
>
>
>
> Sincerely,
> Tony


-- 
Nicolas Lin Wee Kuan