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Virus:Rkit/Agent.nfi
Date discovered:27/04/2009
Type:Trojan
In the wild:Yes
Reported Infections:Low to medium
Distribution Potential:Low to medium
Damage Potential:Medium
Static file:Yes
File size:39.936 Bytes
MD5 checksum:02e1df5942f45880e7aae5adca701e6a
IVDF version:7.01.03.113 - Monday, April 27, 2009

 General Method of propagation:
• Autorun feature


Aliases:
   •  Panda: W32/Autorun.JOO
   •  Eset: Win32/AutoRun.Agent.SD
   •  Bitdefender: Worm.Generic.84374


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


Side effects:
   • Downloads a malicious file
   • Drops malicious files
   • Registry modification

 Files It copies itself to the following locations:
   • %SYSDIR%\system.exe
   • %drive%\system.exe



It deletes the initially executed copy of itself.



The following files are created:

%drive%\AutoRun.inf This is a non malicious text file with the following content:
   • %code that runs malware%

%drive%\AutoRun.vbs This is a non malicious text file with the following content:
   • %code that runs malware%

%SYSDIR%\drivers\Drver.sys Further investigation pointed out that this file is malware, too. Detected as: Rkit/Agent.nfi

%SYSDIR%\syste2.dll Further investigation pointed out that this file is malware, too. Detected as: Worm/Citeary.B.3

%SYSDIR%\syste9.dll Further investigation pointed out that this file is malware, too. Detected as: Rkit/Agent.nfi




It tries to download a file:

– The location is the following:
   • http://ddl.754245.com/05/**********
At the time of writing this file was not online for further investigation.

 Registry The following registry key is added in order to run the process after reboot:

– [HKLM\SYSTEM\CurrentControlSet\Services\CHoook]
   • "DisplayName"="CHoook"
   • "ErrorControl"=dword:0x00000001
   • "ImagePath"="\??\%SYSDIR%\Drivers\Drver.sys"
   • "Start"=dword:0x00000003
   • "Type"=dword:0x00000001



One of the following values is added in order to run the process after reboot:

–  [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "system"="%SYSDIR%\system.exe"

 Process termination List of processes that are terminated:
   • egui.exe
   • ekrn.exe


 Rootkit Technology It is a malware-specific technology. The malware hides its presence from system utilities, security applications and in the end, from the user.


Method used:

Hooks the following API function:
   • NtCreateProcessEx

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

Description inserted by Petre Galan on Friday, February 12, 2010
Description updated by Petre Galan on Friday, February 12, 2010

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