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TROJ_FAKEAV.BSTA

October 09, 2012
 Analysis by: Roland Marco Dela Paz
 ALIASES:

Symantec : Trojan.FakeAV ; Microsoft : Rogue:Win32/Winwebsec

 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 displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to certain sites asking for sensitive information, such as credit card numbers.

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size:

462,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 May 2011

Payload:

Displays fake alerts

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following files:

  • %System Root%\fsqwr.bmp - non-malicious fake alert image file
  • %System Root%\Documents and Settings\All Users\Application Data\{random}\{random} - non-malicious file

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It drops the following copies of itself into the affected system:

  • %System Root%\Documents and Settings\All Users\Application Data\{random}\{random}.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\Documents and Settings\All Users\Application Data\{random}

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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\RunOnce
{random} = %System Root%\Documents and Settings\All Users\Application Data\{random}\{random}.exe

NOTES:

It displays fake alerts that warn users of infection. It also displays fake scanning results of the affected system. It then asks for users to purchase it once scanning is completed. If users decide to purchase the rogue product, users are directed to the following sites asking for sensitive information, such as credit card numbers:

  • http://{BLOCKED}.{BLOCKED}.194.43/
  • http://{BLOCKED}.{BLOCKED}.194.173/

It displays the following fake alerts:

It also prevents executable files from executing. It displays the following fake alert whenever the an infected user tries to execute files:

It does not avoid terminating Windows processes.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.134.08

FIRST VSAPI PATTERN DATE:

05 May 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

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. %System Root%\Documents and Settings\All Users\Application Data\{random}

Step 4

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 Root%\fsqwr.bmp

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\Windows\CurrentVersion\RunOnce
    • {random} = %System Root%\Documents and Settings\All Users\Application Data\{random}\{random}.exe

Step 6

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