BKDR_NETBOT.PCCL

January 10, 2014
 Analysis by: Jennifer Gumban
 ALIASES:

Backdoor:Win32/PcClient.ZL (Microsoft), HEUR:Trojan.Win32.Generic (Kaspersky), Backdoor.Win32.Venik (Ikarus)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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 does not have any propagation routine.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It does not have any downloading capability.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

96,968 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Dec 2013

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%\1482640_res.tmp - also detected as BKDR_NETBOT.PCCL

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops the following component file(s):

  • %System%\R{random characters}C.dll - also detected as BKDR_NETBOT.PCCL

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

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 = "MediaSerial"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MediaSerial
Description = "computer. If this service is stoppet"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\MediaSerial\Parameters
ServiceDll = "%System%\R{random characters}C.dll"

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

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

It connects to the following websites to send and receive information:

  • www.{BLOCKED}dj.com using Port1512

Download Routine

This backdoor does not have any downloading capability.

Information Theft

This backdoor gathers the following information on the affected computer:

  • Computer Name
  • OS Version
  • RAM

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.496.08

FIRST VSAPI PATTERN DATE:

25 Dec 2013

VSAPI OPR PATTERN File:

10.497.00

VSAPI OPR PATTERN Date:

26 Dec 2013

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

Restart in Safe Mode

[ Learn More ]

Step 3

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%\1482640_res.tmp

Step 4

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 = "MediaSerial"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MediaSerial
    • Description = "computer. If this service is stoppet"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MediaSerial\Parameters
    • ServiceDll = "%System%\R{random characters}C.dll"

Step 5

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