Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This backdoor may be dropped by other malware.

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

  TECHNICAL DETAILS

File Size: 62,976 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 03 Apr 2012
Payload: Compromises system security, Connects to URLs/IPs, Modifies system registry

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_MDROP.TPB

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • ER

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\DbxUpdateET
Mark = "NULL"

Backdoor Routine

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

  • Create, Open and Delete Files
  • Create and Delete Directories
  • Search files
  • Get System Information
  • Command Shell
  • Execute files

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

  • {BLOCKED}l.{BLOCKED}o.com

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.884.03
FIRST VSAPI PATTERN DATE: 03 Apr 2012
VSAPI OPR PATTERN File: 8.885.00
VSAPI OPR PATTERN Date: 04 Apr 2012

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_AGENT.TPB

    TROJ_MDROP.TPB

Step 3

Scan your computer with your Trend Micro product and note files detected as BKDR_AGENT.TPB

Step 4

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\DbxUpdateET
    • Mark = NULL

Step 6

Search and delete the file detected as BKDR_AGENT.TPB

*Note: Some component files may be 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.

To manually delete a malware/grayware file from the affected system:

  1. Right-click Start then click Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.

Step 7

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