BKDR_WYSOL.A

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 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

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 executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

  TECHNICAL DETAILS

File Size:

234,011 bytes

File Type:

EXE

Initial Samples Received Date:

01 Mar 2012

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 the following files:

  • %User Temp%\osk.exe
  • %User Temp%\??????.jpg

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Dropping Routine

This backdoor executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.810.05

FIRST VSAPI PATTERN DATE:

01 Mar 2012

VSAPI OPR PATTERN File:

8.811.00

VSAPI OPR PATTERN Date:

02 Mar 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

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %User Temp%\osk.exe
  • %User Temp%\??????.jpg

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_WYSOL.A. 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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