Analysis by: Francis Xavier Antazo
ALIASES:

Backdoor:Win32/PcClient.ZL (MICROSOFT), a variant of Win32/Agent.DKR trojan (NOD32),

 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

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 executes commands from a remote malicious user, effectively compromising the affected system.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size: 39,424 bytes
File Type: EXE
Memory Resident: Yes
Payload: Connects to URLs/IPs, Compromises system security, Collects system information

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.

Installation

This backdoor drops the following files:

  • %User Temp%\(7 random numbers)_Ojie.xml - also detected as BKDR_NETBOT.PCCB

(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.)

It drops the following component file(s):

  • %System%\P(random characters).src - also detected as BKDR_NETBOT.PCCB

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It injects itself into the following processes running in the affected system's memory:

  • svchost.exe

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
krnlsrvc = "{Variable Value 1}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Variable Value 1}
Description = "Provides support for media palyer.This service can't be stoper"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Variable Value 1}\Parameters
ServiceDll = "%System%\P(random characters).src"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Perform remote shell
  • Monitor mouse and keyboard events
  • Uninstall itself
  • Terminate process
  • Capture screenshot
  • Get drive information
  • File Manipulation (Create, Modify, Rename, Copy, Delete)
  • Execute file
  • Send File

Download Routine

This backdoor connects to the following URL(s) to download its configuration file:

  • www.{BLOCKED}n.com/ip2008.txt

Information Theft

This backdoor gathers the following information on the affected computer:

  • Computer Name
  • OS Version
  • RAM

Its configuration file contains the following information:

  • C&C Server

NOTES:

{Variable Value 1} in the registry entry may have the following values:

  • BITS
  • MediaCenter

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.382.05
FIRST VSAPI PATTERN DATE: 01 Jan 2015
VSAPI OPR PATTERN File: 11.383.00
VSAPI OPR PATTERN Date: 02 Jan 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\(7 random numbers)_Ojie.xml
  • %System%\P(random characters).src

Step 5

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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • krnlsrvc = "{Variable Value 1}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{Variable Value 1}
    • Description = "Provides support for media palyer.This service can't be stoper"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{Variable Value 1}\Parameters
    • ServiceDll = "%System%\P(random characters).src"

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_NETBOT.PCCB. 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.

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_NETBOT.PCCB. 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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