WORM_STUXNET.SM

October 08, 2012
 Analysis by: Jeffrey Bernardino
 Modified by: Michael Cabel
 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

Infection Channel:

Propagates via removable drives, Propagates via software vulnerabilities

This is the Trend Micro detection for files that propagate via vulnerablity in Windows Shell that could allow arbitrary commands to be executed.

This Worm drops file(s)/component(s) detected as RTKT_STUXNET.A. It also drops non-malicious files. It drops copy(ies) of itself in all removable drives. It connects to certain URL(s) to check for an internet connection. It hooks certain APIs to hide files with .TMP and .LNK extensions. It drops the file named Copy of Shortcut to.lnk in all removable drives. Trend Micro detects is as EXPL_CPLNK.SM.

This is the Trend Micro detection for files that exhibit certain behaviors.

  TECHNICAL DETAILS

File Size:

517,632 bytes

File Type:

PE

Memory Resident:

No

Initial Samples Received Date:

22 Jul 2010

Payload:

Drops files, Connects to URLs or IP addresses

Installation

This worm drops the following file(s)/component(s):

  • %System%\drivers\mrxcls.sys - detected as RTKT_STUXNET.A
  • %System%\drivers\mrxnet.sys - detected as RTKT_STUXNET.A

(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.)

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\\~WTR4132.tmp
  • {drive letter}:\\~WTR4141.tmp

Other Details

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

  • www.windowsupdate.com
  • www.msn.com

More information on this vulnerability can be found below:

  • Vulnerability in Windows Shell Could Allow Remote Code Execution (2286198)

This is the Trend Micro detection for:

  • Files that propagate via vulnerablity in Windows Shell that could allow arbitrary commands to be executed.

It does the following:

  • Hooks the following APIs to hide files with .TMP and .LNK extensions:
    • FindFirstFileW
    • FindNextFileW
    • FindFirstFileExW
    • NtQueryDirectoryFile
    • ZwQueryDirectoryFile
  • Drops the file named Copy of Shortcut to.lnk in all removable drives. Trend Micro detects is as EXPL_CPLNK.SM.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.330.08

FIRST VSAPI PATTERN DATE:

22 Jul 2010

VSAPI OPR PATTERN File:

7.333.00

VSAPI OPR PATTERN Date:

23 Jul 2010

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

Remove malware files dropped/downloaded by WORM_STUXNET.SM

Step 3

Scan your computer with your Trend Micro product and note files detected as WORM_STUXNET.SM

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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

Step 6

Search and delete the file detected as WORM_STUXNET.SM

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 7

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


Note: To identify STUXNET-infected systems within a network, administrators can use Trend Micro's special STUXNET Scanner Tool. For more details, download and extract the package and refer to the tool's incorporated text file.


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