[unisog] 'bot file servers?

Johannes Ullrich jullrich at sans.org
Wed Apr 30 22:26:23 GMT 2003

Kind of sounds like a possible DDOS net. Essentially the
ICMP packet just triggers a specific packet flood.

Any packet traces? In particular the ICMP packet that
initiates this? Is the source of the ICMP packet always
the target of the UDP stream?

The ICMP packet could be spoofed, or it could some in
response to a spoofed request. In particular as ICMP
errors usually include the packet content, this is a
nice way to bounce a covert channel.

On Wed, 2003-04-30 at 16:47, Jane DelFavero wrote:
> Hi all,
> We have come up against network behavior that I haven't encountered 
> before, and I'd like to hear from anyone who has. We have a couple of 
> machines which are pumping out large volumes of data, but it's not 
> the normal P2P junk, or IRC, as far as we can see. There's an ICMP 
> packet from a remote host, followed by a very large data transfer 
> (about the size of an .avi movie file) via UDP back to that remote 
> site.
> Is this a trojan or backdoor (or other application) that anyone's seen before?
> Thanks, Jane
SANS Internet Storm Center

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