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TROJ_SCAR.MJ

October 08, 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: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This Trojan deletes itself after execution.

  TECHNICAL DETAILS

File Size:

121,026 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Mar 2011

Payload:

Drops files

Installation

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

  • %system%\{random filename}.exe

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

  • PRKUdURU

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

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_PRKUDURU\
0000
Service = PRKUdURU

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_PRKUDURU

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PRKUdURU

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}.com/index.html - inaccessible

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

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

Delete this registry key

[ 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\SYSTEM\CurrentControlSet\Enum\Root\
    • LEGACY_PRKUDURU
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
    • PRKUdURU

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_SCAR.MJ. 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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