TROJ_TRACUR.CX

August 19, 2011
 Analysis by: Cris Pantanilla
 ALIASES:

Trojan.Win32.Menti.hthc (Kaspersky), TrojanDownloader:Win32/Tracur.Y (Microsoft)

 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 Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

802,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Jul 2011

Payload:

Drops files, Modifies system registry, Connects to URLs/IPs

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 file(s)/component(s):

  • %System%\{random numbers}

(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 component file(s):

  • %System%\avmeter32.dll - detected as TROJ_SPNR.0BHC11

(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 copies of itself into the affected system:

  • %System%\avmeter32.exe

(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.)

Autostart Technique

This Trojan adds the following registry keys to install itself as a Browser Helper Object (BHO):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{05D9ED4C-63D9-4CAA-AF04-450DEE991CD5}

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Wmi32
ImagePath = %System%\{DLL name}32.exe

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{ef142848-d763-4a97-a364-a256042c04ff}

It adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\.fsharproj\PersistentHandler
(Default) = "{284a3b40-7a8e-4083-b7ab-9579f5df1e69}"

HKEY_CLASSES_ROOT\Hrkkdxtnkr\CLSID
(Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"

HKEY_CLASSES_ROOT\CLSID\{05D9ED4C-63D9-4CAA-AF04-450DEE991CD5}\
InprocServer32
(Default) = "%System%\avmeter32.dll"

HKEY_CLASSES_ROOT\Software\Hrkkdxtnkr\
CLSID
(Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"

HKEY_CURRENT_USER\Software\Classes\
Software\Hrkkdxtnkr\CLSID
(Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}1.{BLOCKED}7.153.48

However, as of this writing, the said sites are inaccessible.

NOTES:
It searches for DLL files in the System Folder. It then uses the filename of the DLL as follows:

  • {DLL name}32.exe

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.314.16

FIRST VSAPI PATTERN DATE:

28 Jul 2011

Step 1

For Windows ME and XP 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_TRACUR.CX

    TROJ_SPNR.0BHC11

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {05D9ED4C-63D9-4CAA-AF04-450DEE991CD5}  
  • In HKEY_CLASSES_ROOT\CLSID
    • {ef142848-d763-4a97-a364-a256042c04ff}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Wmi32

Step 5

Delete this 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_CLASSES_ROOT\.fsharproj\PersistentHandler
    • (Default) = "{284a3b40-7a8e-4083-b7ab-9579f5df1e69}"
  • In HKEY_CLASSES_ROOT\Hrkkdxtnkr\CLSID
    • (Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"
  • In HKEY_CLASSES_ROOT\CLSID\{05D9ED4C-63D9-4CAA-AF04-450DEE991CD5}\InprocServer32
    • (Default) = "%System%\avmeter32.dll"
  • In HKEY_CLASSES_ROOT\Software\Hrkkdxtnkr\CLSID
    • (Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"
  • In HKEY_CURRENT_USER\Software\Classes\Software\Hrkkdxtnkr\CLSID
    • (Default) = "{ef142848-d763-4a97-a364-a256042c04ff}"

Step 6

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. %System%\{random numbers}

Step 7

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