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 Forums >>  Target Specific - General  >>  What is this packed with?

Topic created on: June 5, 2008 07:52 CDT by curious1 .

Okay, I am trying to dissect what appears to be some kind of IRC based bot that infected a friends computer.  There is one file that is really bugging me though.  I know from the filename that it is probably part of an FTP server, but it has been packed with something - I have tried numerous ways of figuring out the packer, but keep getting inconsistent results.  So far I have had it detect as 'PseduoSigner', 'MEW', 'Neolite' & 'tElock'.  I tried to examin it using StudPE, but just attempting to open it causes StudPE to crash.  I was leaning towards the 'tElock' verdict, until I got poking @ it in OllyDbg (it behaves weirdly).  If anyone could determine what this DLL is packed with (or provide guidance as to how to unpack it), I'd appreciatet it. (BTW, the original file from the FTP product isn't packed, and is of the size 2019328 bytes).  Here is the DLL: http://www.uploading.com/files/YFVDBJPL/pkdDLL.7z.html

  TQN     June 5, 2008 08:24.32 CDT
An UPX Scranbler. Open file with PE Explorer and save as new .exe file.

  curious1   June 5, 2008 08:52.05 CDT
> TQN: An UPX Scranbler. Open file with PE Explorer and save as new .exe file.

Tried that already and it doesn't work.  Just tried again:

: Open File: Serv-U.dll
: File size: 1118208 bytes.
: Using the Plug-in subsystem...
: Upack Unpacker Plug-in: Executing...
: Upack Unpacker Plug-in: <Upack> The file is not Upacked.
: Upack Unpacker Plug-in: not accomplished.
: UPX Unpacker Plug-in: Executing...
: UPX Unpacker Plug-in: <UPX> The file is not UPXed.
: UPX Unpacker Plug-in: not accomplished.
: The Plug-in subsystem finished.

That is with PE Explorer v1.99
Also, saving back to a new file produces a file of the wrong size (way too small).

  b0ne     June 5, 2008 10:47.57 CDT
It looks like it really is a Serv-U component DLL.  The problem with unpacking this guy is that it imports RhinoGui.Dll, RhinoNet.dll, and the microsoft 2005 c/c++ runtimes which need to be installed.  You could hack up the resource and import directories but that gets ugly fast.


I installed the Serv-U trial from RhinoSoft, renamed the Serv-U.dll that was installed to Serv-U.dll.bak, and copied the one that you posted in the directory and loaded it in Ollydbg.

If you set a breakpoint at 0x101FD13B (JMP Serv-U.100CC372), when it hits, step it and you're at OEP.  Dump and import fix.

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