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BKDR_TENPEQ.SM

July 30, 2013
 Analysis by: Alvin Bacani
 ALIASES:

Backdoor:Win32/Tenpeq.gen!A (Microsoft); Trojan-Downloader.Win32.Agent.usfc (Kaspersky)

 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: No

  • 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.

  TECHNICAL DETAILS

File Size:

102,400 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

26 Jul 2013

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 and executes the following files:

  • %System%\mpeg4c32.dll - detected as BKDR_TENPEQ.OMU
  • %System%\tcpipport.sys - detected as RTKT_TENPEQ.OMU

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

Autostart Technique

This backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIPPORT
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIPPORT
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIPPORT
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIPPORT
ImagePath = \??\C:\WINDOWS\system32\tcpipport.sys

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIPPORT
DisplayName = "TCPIPPORT"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS
WOW64 = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS
Start = "2"

(Note: The default value data of the said registry entry is "3".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS\Parameters
ServiceDll = %System%\mpeg4c32.dll

(Note: The default value data of the said registry entry is %system%\qmgr.dll.)

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows NT\CurrentVersion\
SvcHost

  SOLUTION

Minimum Scan Engine:

9.300

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 these files

[ 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.
  • %System%\mpeg4c32.dll
  • %System%\tcpipport.sys

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\Wow6432Node\Microsoft\Windows NT\CurrentVersion
    • SvcHost
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • TCPIPPORT

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\SYSTEM\CurrentControlSet\Services\BITS
    • WOW64 = "1"

Step 6

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BITS
    • From: Start = "2"
      To: Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BITS\Parameters
    • From: ServiceDll = %System%\mpeg4c32.dll
      To: ServiceDll = %system%\qmgr.dll

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_TENPEQ.SM. 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 8

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. DATA_GENERIC
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.

    • • For Windows Vista and Windows 7 users:

    1. Click Start>Computer.
    2. In the Search input box, type the following:
      DATA_GENERIC
    3. Once located, select the file then press SHIFT+DELETE to delete it.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.


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