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BKDR_SMALL.ABF

October 09, 2012
 Analysis by: Jed Valderama
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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

It reads its configuration file that contains commands and data to be sent to a remote server.

It exports functions used by other malware. It requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size:

76,000 bytes

File Type:

DLL

Memory Resident:

No

Initial Samples Received Date:

31 Jul 2012

Arrival Details

This backdoor may arrive bundled with malware packages as a malware component.

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

Backdoor Routine

This backdoor reads its configuration file that contains commands and data to be sent to a remote server.

Information Theft

This backdoor s configuration file contains the following information:

  • "SrvCode"
  • "SrvHash"
  • "DrvCode"
  • "DrvHash"

Other Details

This backdoor exports functions used by other malware.

It requires its main component to successfully perform its intended routine.

NOTES:

This backdoor searches for another component before performing its malicious routine. The component is specified in the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\{B28E0E78-882D-403c-AF4E-BDEC9C8FA37B}\ServiceArg

It searches for its configuration file %Windows%\Media\Windows Config.wav.

Based on its code, this backdoor has the following capabilities:

  • Connect to a remote machine using the details in its configuration file
  • Connect to a website to download other files using the details in its configuration file

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.296.01

FIRST VSAPI PATTERN DATE:

31 Jul 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

Scan your computer with your Trend Micro product and note files detected as BKDR_SMALL.ABF

Step 3

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\CurrentVersion\{B28E0E78-882D-403c-AF4E-BDEC9C8FA37B}
    • ServiceArg

Step 4

Search and delete the file detected as BKDR_SMALL.ABF

*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 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_SMALL.ABF. 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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