RE: suspicious firewall rules in WinXP firewall

One of the worst shareware infections we've seen here was
redirecting all DNS traffic for the infected machine to a
site in Eastern Europe. When that site got taken down, DNS
resolution for the client stopped (which is what you're seeing),
and that's how we got the ticket to investigate.

David Gillett


-----Original Message-----
From: belka@xxxxxxx [mailto:belka@xxxxxxx]
Sent: Friday, June 30, 2006 1:32 PM
To: incidents@xxxxxxxxxxxxxxxxx
Subject: suspicious firewall rules in WinXP firewall

While setting a port for Symantec to query XP Pro
workstations for virus updates, I noticed two machines that
had firewall rules (exceptions in WinXP firewall parlance)
that were in unreadable charcaters, such as an asian font set
that couldn't be displayed. The rule name was in blocks or in
other unreadable characters. The user of these two
workstations is notorious for downloading asian TV shows over
bit torrent, and visiting anime and other asian sites.

I deleted the two firewall rules (DOH! I should have just
disabled them) and now IE and Mozilla browsers do not work at
all. I can ping out of these two machines, and as long as I
use an IP address, these machines can ping anywhere in the
Internet. However, if any call to DNS is requires, either
with a browser or ICMP, it fails.

Has anyone had a similar experience or seen this kind of
behavior. My fear is that one of the "special Korean
download programs" that this user admits installing has
altered the browser or -- even worse - the XP TCP/IP stack
with hooks into a trojan or spyware product. I tried
disabling the firewall to allow all traffic in and out, but
to no effect. No DNS functionality. My packet traces are
inconclusive and my IDS is not alerting on anything in or out
of these two work stations.

Any ideas? At this point I know I am going to have to
reload, but from a forensic stand point, I am curious if any
one else has seen this kind of beavior before.

Thanks.

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This List Sponsored by: Black Hat

Attend the Black Hat Briefings & Training USA, July 29-August 3 in Las Vegas.
World renowned security experts reveal tomorrow's threats today. Free of
vendor pitches, the Briefings are designed to be pragmatic regardless of your
security environment. Featuring 36 hands-on training courses and 10 conference
tracks, networking opportunities with over 2,500 delegates from 40+ nations.

http://www.blackhat.com
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