Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

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 drop any other file.

  TECHNICAL DETAILS

File Size: 45,056 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Jun 2012
Payload: Compromises system security

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.

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Start a remote Command Prompt
  • List files
  • Delete a file
  • Enumerate all network connections
  • Terminate a process
  • Enumerate processes
  • Execute a file
  • Download a file from the C&C server

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

  • http://{BLOCKED}.{BLOCKED}.242.84/{random characters}

Dropping Routine

This backdoor does not drop any other file.

NOTES:

This backdoor does not have rootkit capabilities.

This backdoor does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.188.03
FIRST VSAPI PATTERN DATE: 13 Jun 2012
VSAPI OPR PATTERN File: 9.189.00
VSAPI OPR PATTERN Date: 13 Jun 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

Identify and terminate files detected as BKDR_SMALL.MYL

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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