BKDR_REMOSH.BD

 Analysis by: Jasen Sumalapao

 ALIASES:

Backdoor:Win32/Remosh.gen!A (Microsoft), Trojan.Gen (Symantec), Gen:Trojan.Heur.FU.bqW@a8UY8zdi (FSecure), TR/Dropper.Gen (Antivir), Gen:Trojan.Heur.FU.bqW@a8UY8zdi (Bitdefender), PUA.Win32.Packer.SetupExeSection (Clamav), Win32/Agent.PGE trojan (NOD32), Suspicious file (Panda), TrojanDropper.Agent.fsix (VBA32)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This backdoor may be dropped by other malware. It may be manually installed by a user.

It uses common file icons to trick a user into thinking that the files are legitimate.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

26,624 bytes

File Type:

EXE

Initial Samples Received Date:

12 Sep 2012

Arrival Details

This backdoor may be dropped by the following malware:

  • SWF_DROPPER.BD

It may be manually installed by a user.

Installation

This backdoor drops the following component file(s):

  • %System%\recycler32.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Its DLL component is injected to the following process(es):

  • svchost.exe

It uses common file icons to trick a user into thinking that the files are legitimate.

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
ImagePath = %systemroot%\system32\svchost.exe -k netsvcs

Other System Modifications

This backdoor adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Parameters
ServiceDll = %System%\recycler32.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Security
Security = {random value}

Other Details

This backdoor deletes itself after execution.