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TROJ_DUQU.B

October 21, 2011
 Analysis by: Erika Bianca Mendoza
 Modified by: Christopher Daniel So
 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 malware is possibly connected with DUQU malware, which shares code similarities in STUXNET malware.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan executes its main SYS component by installing it as a service. It does this by adding a registry key.

It also adds certain registry entries to install the .SYS file.

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:

241,664 bytes

File Type:

DLL

Initial Samples Received Date:

01 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 files:

  • %System%\drivers\cmi4432.sys - detected by Trend Micro as RTKT_DUQU.A
  • %Windows%\inf\cmi4432.PNF - detected by Trend Micro as TROJ_DUQU.ENC
  • %Windows%\inf\cmi4464.PNF - detected by Trend Micro as TROJ_DUQU.CFG

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

NOTES:

It executes its main SYS component by installing it as a service. It does this by adding the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432

It also adds the following registry entries to install the .SYS file:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
Description = "cmi4432"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
DisplayName = "cmi4432"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
Group = "Network"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
ImagePath = "\??\C:\WINDOWS\system32\Drivers\cmi4432.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432
FILTER = "{random values}"

As a result, the routines of RTKT_DUQU.A (.SYS files) are also exhibited on the system.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.540.07

FIRST VSAPI PATTERN DATE:

01 Nov 2011

VSAPI OPR PATTERN File:

8.541.00

VSAPI OPR PATTERN Date:

01 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

Remove malware files dropped/downloaded by TROJ_DUQU.B

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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\Services\
    • cmi4432

Step 5

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