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BKDR_FEXEL.SM2

September 26, 2013
 ALIASES:

Backdoor.Fexel (Symantec)

 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

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 is a component of other malware.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

32,768 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

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

  • GDGSYDLYR_%Random%

It is a component of other malware.

Backdoor Routine

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

  • File Management (Create, Delete, Move)
  • Downloads & Execute Files
  • Terminate Processes
  • Execute Command Shell

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.228.102/info.asp
  • {BLOCKED}.117.90/info.asp
  • {BLOCKED}.158.5/info.asp

As of this writing, the said sites are inaccessible.

NOTES:
It sends the following information to the URL upon connection:

  • Computer Name
  • Current User Name
  • Get OS Version
  • Volume Information

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.288.05

FIRST VSAPI PATTERN DATE:

24 Sep 2013

VSAPI OPR PATTERN File:

10.289.00

VSAPI OPR PATTERN Date:

24 Sep 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

Scan your computer with your Trend Micro product and note files detected as BKDR_FEXEL.SM2

Step 3

Search and delete files detected as BKDR_FEXEL.SM2

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_FEXEL.SM2. 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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