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WORM_STUXNET.AA

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 ALIASES:

TrojanDropper:Win32/Stuxnet.A (Microsoft); Worm.Win32.Stuxnet.m (Kaspersky); Win32.Worm.Stuxnet.A (FSecure); W32/Stuxnet.A!tr (Fortinet); Trojan.Win32.Chifrax (Ikarus); Win32/Stuxnet.A worm (Nod32);

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This worm arrives via removable drives. It 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 dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

774,676 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Apr 2011

Arrival Details

This worm arrives via removable drives.

It 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 worm drops the following component file(s):

  • %System%\drivers\mrxcls.sys
  • %System%\drivers\mrxnet.sys

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following non-malicious files:

  • %Windows%\inf\mdmcpq3.PNF
  • %Windows%\inf\mdmeric3.PNF
  • %Windows%\inf\oem6C.PNF
  • %Windows%\inf\oem7A.PNF

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

Dropping Routine

This worm drops the following files:

  • %User Temp%\malware.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.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This worm connects to the following URL(s) to check for an Internet connection:

  • www.windowsupdate.com

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

7.952.07

FIRST VSAPI PATTERN DATE:

05 Apr 2011

VSAPI OPR PATTERN File:

7.953.00

VSAPI OPR PATTERN Date:

06 Apr 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

Restart in Safe Mode

[ Learn More ]

Step 3

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.  %User Temp%\malware.exe
%System%\drivers\mrxcls.sys
%System%\drivers\mrxnet.sys
%Windows%\inf\mdmcpq3.PNF
%Windows%\inf\mdmeric3.PNF
%Windows%\inf\oem6C.PNF
%Windows%\inf\oem7A.PNF

Step 4

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