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BKDR_PCLIENT.XPI

November 04, 2014
 Analysis by: Francis Xavier Antazo
 ALIASES:

Trojan horse BackDoor.Generic14.AJFC (AVG), Backdoor.PcClient (VBA32)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It arrives as a component bundled with malware/grayware packages.

  TECHNICAL DETAILS

File Size:

4,496,976 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

30 Oct 2014

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It arrives as a component bundled with malware/grayware packages.

Installation

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

  • %User Temp%\(random file name 1).exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other System Modifications

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

HKEY_LOCAL_MACHINE\System\ControlSet001\
Control\Session Manager
PendingFileRenameOperations = "\??\C:\%User Temp%\(random file name 1).exe"

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.256.02

FIRST VSAPI PATTERN DATE:

04 Nov 2014

VSAPI OPR PATTERN File:

11.257.00

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Delete this registry value

[ 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\System\ControlSet001\Control\Session Manager
    • PendingFileRenameOperations = "\??\C:\%User Temp%\(random file name 1).exe"

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_PCLIENT.XPI. 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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