Analysis by: Roland Marco Dela Paz
 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 207,872 bytes
File Type: PE
Memory Resident: No
Initial Samples Received Date: 06 Oct 2010

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

Installation

This Trojan adds 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:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It drops the following files:

  • %Application Data%\{Random CLSID for Firefox}\chrome.manifest - non-malicious component
  • %Application Data%\{Random CLSID for Firefox}\install.rdf - non-malicious component
  • %Application Data%\{Random CLSID for Firefox}\chrome\content\_cfg.js - non-malicious component
  • %Application Data%\{Random CLSID for Firefox}\chrome\content\overlay.xul - non-malicious component

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\
Firefox\Extensions
{Random CLSID for Firefox} = {malware path and filename}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random} = rundll32.exe "{malware path and filename}",Startup

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\{Random CLSID for Firefox}

Process Termination

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

  • mrt.exe

Other Details

This Trojan does the following:

  • It also monitors the IE browser when the user accesses sites with the following strings:
    ads.ask.com
    /pagead/ads?
    /ra/click
    .yahoo.
    /aclk
    .msn.
    .live.
    mywebsearch.
    search.aol.
    query=
    .aol.
    searchfor=
    tbr.ask.
    /web?
    /search
    .bing.
    search.store.yahoo.
    search.yahoo.
    /custom
    search
    .google.
  • It then sends the search string along with other information to its server and it replies with an ad that is related to the search string.
  • It attempts to download a possibly malicious file from the following file hosting site:
    http://{random}.{BLOCKED}ros.com/get2.php?c={parameters}&d={parameters}
    As of writing, the file it attempts to download is unavailable.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.516.01
VSAPI PATTERN Date: 06 Oct 2010
VSAPI PATTERN Date: 10/6/2010 12:00:00 AM

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

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.  %Application Data%\{Random CLSID for Firefox}

Step 4

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

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
    • {Random CLSID for Firefox}

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_MUFANOM.AI. 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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