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Virus:TR/Drop.TDss.akfb
Date discovered:22/04/2011
Type:Trojan
In the wild:Yes
Reported Infections:Low
Distribution Potential:Medium to high
Damage Potential:Low to medium
File size:58.888 Bytes
MD5 checksum:60184EE7316CFC9F734CF9713FD76361
VDF version:7.11.06.232 - Friday, April 22, 2011
IVDF version:7.11.06.232 - Friday, April 22, 2011

 General Method of propagation:
   • Autorun feature
   • Mapped network drives


Aliases:
   •  Symantec: W32.SillyFDC
   •  Kaspersky: Trojan-Dropper.Win32.TDSS.akfb
   •  TrendMicro: TROJ_KRYPTO.SMII
   •  Microsoft: Worm:Win32/Rorpian


Platforms / OS:
   • Windows 2000
   • Windows XP
   • Windows 2003
   • Windows Vista
   • Windows 7


Side effects:
   • Drops files
   • Registry modification

 Files It deletes the initially executed copy of itself.



The following files are created:

%TEMPDIR%\srv%hex number%.tmp Further investigation pointed out that this file is malware, too. Detected as: TR/Drop.TDss.akfb

%TEMPDIR%\srv%hex number%.ini Contains parameters used by the malware.



It tries to download a file:

– The location is the following:
   • http://web-soft2011pc.**********/soft/installer_m_161.exe
It is saved on the local hard drive under: %TEMPDIR%\%number%.tmp At the time of writing this file was not online for further investigation.

 Registry The following registry keys are added in order to load the service after reboot:

– [HKLM\SYSTEM\ControlSet001\Services\srv%hex number%]
   • "Type"=dword:00000014
   • "Start"=dword:00000002
   • "ErrorControl"=dword:00000001
   • "ImagePath"="%systemroot%\system32\svchost.exe -k netsvcs"
   • "DisplayName"="srv%hex number%"
   • "ObjectName"="LocalSystem"



The following registry key is added:

– [HKLM\SYSTEM\ControlSet001\Services\srv%hex number%\
   parameters]
   • "servicedll"="\\?\globalroot\Device\HarddiskVolume1\Documents and Settings\%current username%\Local Settings\Temp\srv%hex number%.tmp"

 File details Programming language:
The malware program was written in MS Visual C++.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with a runtime packer.

Description inserted by Andrei Ilie on Monday, August 1, 2011
Description updated by Andrei Ilie on Wednesday, August 3, 2011

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