TROJ_FAKEMS.JWE

October 09, 2012
 Modified by: Joseph Obed
 ALIASES:

Trojan-Downloader.Win32.AutoIt.te [Kaspersky]

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size:

503,836 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Nov 2011

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 and executes them:

  • %Windows%\wscntfy32.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It drops the following files:

  • %Windows%\encoder.txt

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%Windows%\wscntfy32.exe,%Windows%\help\svchost.exe"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}s.{BLOCKED}2.org/encoder.txt?{random number}

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.610.03

FIRST VSAPI PATTERN DATE:

28 Nov 2011

VSAPI OPR PATTERN File:

8.611.00

VSAPI OPR PATTERN Date:

29 Nov 2011

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 TROJ_FAKEMS.JWE

[ 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

Restore this modified registry value

[ 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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%Windows%\wscntfy32.exe,%Windows%\help\svchost.exe"
      To: Userinit = "%System%\userinit.exe,"

Step 4

Search and delete this file

[ 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.
  • %Windows%\encoder.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEMS.JWE. 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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