full-disclosure - W32/Welchia, W32/Nachi backdoor?

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Message-ID: <200308201349.51616.jstewart@lurhq.com>
From: jstewart at lurhq.com (Joe Stewart)
Subject: W32/Welchia, W32/Nachi backdoor?

On Wednesday 20 August 2003 11:20 am, Barry Irwin wrote:
> >creates a backdoor listening on TCP/707 or some other randomly chosen port
>
> between TCP/666 and >TCP/765 [2]
>
> Telnetting to this port seems to disconnected after 1-5 characters have
> been entered?  This doesn't look like TFTP (port 65/tcp&UDP), and the
> windows tftp client doesn't seem to offer any means of specifying a port to
> connect to?
>
> Is this some kind of password protected backdoor ?

No, it's a reverse shell. Telnet to the port and enter the following 2 lines
to see how it works:

Microsoft Windows
system32>

-Joe

-- 
Joe Stewart, GCIH 
Senior Security Researcher
LURHQ Corporation
http://www.lurhq.com/