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Virus:BDS/Delf.spu
Date discovered:21/02/2010
Type:Backdoor Server
In the wild:Yes
Reported Infections:Low to medium
Distribution Potential:Low to medium
Damage Potential:Low to medium
Static file:Yes
File size:144.384 Bytes
MD5 checksum:3be1031ad44efb92061d9ac9790968ad
IVDF version:7.10.04.107 - Saturday, February 20, 2010

 General Aliases:
   •  Panda: Trj/KillAV.NB
   •  Eset: Win32/AutoRun.IRCBot.DZ
   •  Bitdefender: Trojan.Generic.3536156


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


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

 Files It copies itself to the following location:
   • %SYSDIR%\wmiscvr.exe



It deletes the initially executed copy of itself.




It tries to download a file:

The location is the following:
   • http://rix.messenger-update.su/**********




It tries to executes the following files:

Filename:
   • ipconfig /flushdns


Filename:
   • CMD /C net stop K7RTScan


Filename:
   • CMD /C sc stop K7RTScan


Filename:
   • net stop K7RTScan


Filename:
   • "%SYSDIR%\wmiscvr.exe"


Filename:
   • sc stop K7RTScan


Filename:
   • net1 stop K7RTScan

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

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "ctfmon.exe"="ctfmon.exe"



The values of the following registry keys are removed:

–  [HKLM\SECURITY\RXACT]
   • Log

–  [HKLM\SOFTWARE\Microsoft\PCHealth\ErrorReporting\DW]
   • DWFileTreeRoot



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

[HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\
   FirewallPolicy\StandardProfile\AuthorizedApplications\List]
   • "%SYSDIR%\wmiscvr.exe"="%SYSDIR%\wmiscvr.exe:*:Enabled:DHCP Router"

[HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\
   FirewallPolicy\DomainProfile\AuthorizedApplications\List]
   • "%SYSDIR%\wmiscvr.exe"="%SYSDIR%\wmiscvr.exe:*:Enabled:DHCP Router"



The following registry keys are added:

[HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\
   Image File Execution Options\ctfmon.exe]
   • "Debugger"="wmiscvr.exe"

[HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\
   Layers]
   • "%SYSDIR%\wmiscvr.exe"="DisableNXShowUI"



The following registry keys are changed:

[HKLM\SECURITY\Policy\Secrets\SAC\CupdTime]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAI\CupdTime]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAC\OldVal]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAI\OupdTime]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAI\CurrVal]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAC\CurrVal]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAI\OldVal]
   New value:
   • "@"=""

[HKLM\SECURITY\Policy\Secrets\SAC\OupdTime]
   New value:
   • "@"=""

 Injection It injects itself as a remote thread into a process.

    Process name:
   • explorer.exe


 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, May 21, 2010
Description updated by Petre Galan on Friday, May 21, 2010

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