Analysis by: Erika Bianca Mendoza
ALIASES:

Backdoor:Win32/Poison.M (Microsoft); W32/POISON.SMI!tr (Fortinet); Backdoor.Delf.HVH (F-Secure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor may be dropped by other malware.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 27136 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 14 Mar 2011

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_ADOBFP.SM

Installation

This backdoor drops the following copies of itself into the affected system:

  • %Windows%\EXPL0RER.EXE

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{CBFCF6A3-403D-98F9-223F-03EB127AFEE0}
StubPath = "%Windows%\EXPL0RER.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{CBFCF6A3-403D-98F9-223F-03EB127AFEE0}

Other Details

This backdoor deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 8.900

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by BKDR_POISON.SMI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {CBFCF6A3-403D-98F9-223F-03EB127AFEE0}

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_POISON.SMI. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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