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Virus:Worm/Yimfoca.A.26
Date discovered:08/05/2011
Type:Worm
In the wild:Yes
Reported Infections:Low
Distribution Potential:Low to medium
Damage Potential:Medium
Static file:Yes
File size:102.400 Bytes
MD5 checksum:E0C14BB30E933E58345F66A41B77C260
VDF version:7.11.07.177 - Sunday, May 8, 2011
IVDF version:7.11.07.177 - Sunday, May 8, 2011

 General Method of propagation:
   • Messenger


Aliases:
   •  Kaspersky: Trojan.Win32.Jorik.Lolbot.nv
   •  TrendMicro: WORM_YIMFOCA.F
   •  Sophos: Mal/Agent-ACA


Platforms / OS:
   • Windows 2000
   • Windows XP
   • Windows 2003
   • Windows Vista
   • Windows Server 2008
   • Windows 7


Side effects:
   • Third party control
   • Lowers security settings
   • Registry modification


Right after execution it runs a windows application which will display the following window:

 Files It copies itself to the following location:
   • %WINDIR%\csrss.exe




It tries to execute the following files:

– Filename:
   • net
using the following command line arguments: stop wuauserv


– Filename:
   • net
using the following command line arguments: stop MsMpSvc


– Filename:
   • sc
using the following command line arguments: config wuauserv start= disabled


– Filename:
   • sc
using the following command line arguments: config MsMpSvc start= disabled


– Filename:
   • netsh
using the following command line arguments: firewall add allowedprogram 1.exe 1 ENABLE


– Filename:
   • explorer.exe
using the following command line arguments: http://browseusers.myspace.com/Browse/Browse.aspx

 Registry The following registry keys are added in order to run the processes after reboot:

– [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "Windows System Devices Manager"="%WINDIR%\csrss.exe"

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   • "Windows System Devices Manager"="%WINDIR%\csrss.exe"

– [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Terminal Server\
   Install\Software\Microsoft\Windows\CurrentVersion\Run]
   • "Windows System Devices Manager"="%WINDIR%\csrss.exe"



It creates the following entry in order to bypass the Windows XP firewall:

– [HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\
   FirewallPolicy\StandardProfile\AuthorizedApplications\List]
   • "%executed file%"="%WINDIR%\csrss.exe:*:Enabled:Windows System
      Devices Manager"



The following registry keys are changed:

– [HKCR\TypeLib\{1EA4DBF0-3C3B-11CF-810C-00AA00389B71}\1.1\0\win32]
   New value:
   • "(Default)" = "oleacc.dll"

– [HKLM\SYSTEM\CurrentControlSet\Services\wuauserv]
   Old value:
   • "Start" = dword:00000001
   New value:
   • "Start" = dword:00000004

 Messenger It is spreading via Messenger. The characteristics are described below:

– Yahoo Messenger

 IRC To deliver system information and to provide remote control it connects to the following IRC Server:

Server: 100m**********.ru
Port: 2866

Server: **********.160.147.53
Port: 2866



– This malware has the ability to collect and send information such as:
    • Platform ID
    • Information about the Windows operating system


– Furthermore it has the ability to perform actions such as:
    • connect to IRC server
    • disconnect from IRC server

 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 Tuesday, September 13, 2011
Description updated by Andrei Ivanes on Thursday, September 22, 2011

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