Analysis by: Kathleen Notario

ALIASES:

Trojan.Gen.2 (Symantec); Mal/Tracur-C (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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: 539,648 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Jul 2011
Payload: Terminates processes, hijacks search results

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%\{random file name}32.dll - also detected as TROJ_TRACUR.SMWX
  • %System%\1243398548 - non-malicious file

(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%\{random file name}32.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 registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random service name}32
ImagePath = "%System%\{random file name}32.exe"

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CLASSES_ROOT\CLSID\{random CLSID}\
InprocServer32
(default) = "%System%\{random file name}32.dll"

It registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{random CLSID}

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
XMLHTTP_UUID_Default = "{hex values}"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Internet Explorer\Main
XMLHTTP_UUID_Default = "{hex values}"

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

HKEY_CLASSES_ROOT\.fsharproj

HKEY_CLASSES_ROOT\Hrkkdxtnkr

HKEY_CLASSES_ROOT\CLSID\{random CLSID}

HKEY_CLASSES_ROOT\Software\Hrkkdxtnkr

HKEY_CURRENT_USER\Software\Hrkkdxtnkr

HKEY_USERS\.DEFAULT\Software\
Hrkkdxtnkr

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • chrome.exe

NOTES:

It opens the following registry key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\ProfileList

It then queries the data under the value ProfileImagePath for the subkeys under the said key. For the paths that it finds, it then appends the following:

  • \Application Data\Mozilla\Firefox\Profiles\*

It creates the following folders under the found paths:

  • \extensions\{random CLSID for Firefox}
  • \extensions\{random CLSID for Firefox}\chrome
  • \extensions\{random CLSID for Firefox}\defaults
  • \extensions\{random CLSID for Firefox}\defaults\preferences

For example:

  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{ab2b9058-b165-4c0e-994c-4669ed0054d4}

It also creates the following non-malicious files:

  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{random CLSID for Firefox}\chrome\xulcache.jar
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{random CLSID for Firefox}\chrome.manifest
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{random CLSID for Firefox}\defaults\preferences\xulcache.js
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{random CLSID for Firefox}\install.rdf

It does the same routine for the following:

  • \Local Settings\Application Data\Google\Chrome\User Data\Default

It then creates the following folder:

  • %Application Data%\Google\Chrome\User Data\Default\Default\{random folder name}

It then creates the following non-malicious files:

  • %Application Data%\Google\Chrome\User Data\Default\Default\{random folder name}\contentscript.js
  • %Application Data%\Google\Chrome\User Data\Default\Default\{random folder name}\manifest.json

It may hijack search results. It affects the Mozilla Firefox browser and specifically targets the following search engines:

  • AOL
  • Ask
  • Bing
  • Google
  • Yahoo!

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.299.00
FIRST VSAPI PATTERN DATE: 19 Jul 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

Delete the created random CLSID 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.

Step 4

To delete the random service key this malware/grayware created:

  1. Scan your computer with your Trend Micro product and take note of the name of the malware/grayware/spyware detected.
  2. Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.
  3. Press CTRL+F.
  4. In the Find dialog box, type the file name of the malware detected earlier.
    (Note: Make sure that only the data checkbox is selected, then click Find Next.)
  5. find.

  6. Once found, in the right panel, check if the result is the following value-data pair:
    ImagePath = {malware/grayware path and file name}
  7. If yes, in the left panel, locate the service where the data is under.
  8. Right-click on the located service in the left panel and choose Delete.
  9. Repeat steps 2 to 6 until the Finished searching through the registry dialog box appears.
  10. Close Registry Editor.

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_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • XMLHTTP_UUID_Default = {hex values}
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Internet Explorer\Main
    • XMLHTTP_UUID_Default = {hex values}

Step 6

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_CLASSES_ROOT
    • .fsharproj
  • In HKEY_CLASSES_ROOT
    • Hrkkdxtnkr
  • In HKEY_CLASSES_ROOT\CLSID
    • {random CLSID}
  • In HKEY_CLASSES_ROOT\Software
    • Hrkkdxtnkr
  • In HKEY_CURRENT_USER\Software
    • Hrkkdxtnkr
  • In HKEY_USERS\.DEFAULT\Software
    • Hrkkdxtnkr

Step 7

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%\1243398548

Step 8

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Profile%\Application Data\Mozilla\Firefox\Profiles\{random}.default\extensions\{random CLSID for Firefox}
  • %Application Data%\Google\Chrome\User Data\Default\Default\{random folder name}

Step 9

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