PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 372,736 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 03 Feb 2012

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %User Temp%\audiosrv.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

The dropped copy of itself attempts to load the following possibly malicious file if present on the affected system:

  • %User Temp%\{random number}.tmp

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 8.751.00
VSAPI OPR PATTERN Date: 03 Feb 2012

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

Terminate a process file/s detected as TROJ_KRYPTK.SMU4

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

Step 3

Search and delete these components

[ Learn More ]
There may be some components 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%\{random number}.tmp


  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.
  • Repeat the said steps for all files listed.

    • • For Windows Vista and Windows 7 users:

    1. Click Start>Computer.
    2. In the Search input box, type:
    3. %User Temp%\{random number}.tmp

  • Once located, select the file then press SHIFT+DELETE to delete it.
  • Repeat the said steps for all files listed.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    • Step 4

    Scan your computer with your Trend Micro product to delete files detected as TROJ_KRYPTK.SMU4. 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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