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[Full-Disclosure] W32/Welchia, W32/Nachi backdoor?




From the AUSCERT announcement

>It usually arrives as DLLHOST.EXE (~10,240 bytes) and opens port 707, for
its malicious routines. >Similar to the earlier MSBLAST worm variants, this
malware also exploits the RPC DCOM Buffer >Overflow,and instructs target
systems to download its copy from the affected system using the TFTP
>program [1]

>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 ?

Barry

[1]http://www.auscert.org.au/render.html?it=3359&cid=1
[2]http://securecomputing.stanford.edu/win-rpc.html
--
Barry Irwin
bvi@moria.org
http://lair.moria.org

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