OSEC

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New http attack?

From: Keith T. Morgan (keith.morganterradon.com)
Date: Wed Jun 08 2005 - 11:04:37 CDT


A google search didn't turn up anything of value on this, so I'm posting
to the list. If I've missed something that's common knowledge here, I
appologize for inverting the signal/noise ratio a bit with this post.

We've seen an attack that triggered a snort bleeding-edge hit for "smb
over http authentication." This isn't particularly alarming, but, what
caught my attention is what appears to be a very large buffer in part of
the packet.

The ascii decoded capture looks a bit like this:

GET / HTTP/1.0
Host: obfuscated
Authorization: Negotiate <what may be an encrypted password>
QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB.

This "QUFB" string is repeated for 1400 bytes or so, and I'm assuming
went beyond the single packet capture I have.

The IIS logs indicate a simple GET / with a 401 response code.

Has anyone seen this "QUFBQUFB" string in a worm, virus, or exploit
floating around out there somewhere? I think chances of this being a FP
are low since we're not using NTLM or windows native/ad authentication
on this site.

-- Keith Morgan
-- CISSP, MCP, CCSE/CCSA

"Hey Pants... Any advice for getting through turn 1 with 55 motorcycles
on the grid?"
"Yeah. Don't Crash."
-- Sage motorcycle roadracing advice from Shawn (Pants) Romano
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