Analysis by: Sabrina Lei Sioting
 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: 245,760 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 07 Jul 2011
Payload: Drops files, Creates files, Modifies system registry

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:

  • %Application Data%\{random CLSID for Firefox}\chrome\content\overlay.xul - non-malicious
  • %Application Data%\{random CLSID for Firefox}\chrome\content\_cfg.js - detected by as JS_GORD.F
  • %Application Data%\{random CLSID for Firefox}\chrome.manifest - non-malicious
  • %Application Data%\{random CLSID for Firefox}\install.rdf - non-malicious

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It creates the following folders:

  • %Application Data%\{random CLSID for Firefox}
  • %Application Data%\{random CLSID for Firefox}\chrome
  • %Application Data%\{random CLSID for Firefox}\chrome\content

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = rundll32.exe "{malware path and file name}",Startup

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\
Firefox\Extensions
{Random CLSID for Firefox} = %Application Data%\{random CLSID for Firefox}

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\{random characters}

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.271.00
FIRST VSAPI PATTERN DATE: 07 Jul 2011

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Remove the malware/grayware file dropped/downloaded by TROJ_HILOTI.SMEA

    JS_GORD.F

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_HILOTI.SMEA

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    • {random characters}

Step 6

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\Windows\CurrentVersion\Run
    • {random} = rundll32.exe {malware path and filename},Startup
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Firefox\Extensions
    • {Random CLSID for Firefox} =%Application Data%\{random CLSID for Firefox}

Step 7

Search and delete these folders

[ 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.  %Application Data%\{random CLSID for Firefox}

Step 8

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