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TROJ_FAKEAV.DFL

October 09, 2012
 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.

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

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 a certain website asking for sensitive information, such as credit card numbers. When users agree to buy the software, it connects to a certain URL.

  TECHNICAL DETAILS

File Size:

428,544 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Oct 2011

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 non-malicious files:

  • %Documents and Settings%\All Users\Application Data\{random}
  • %Documents and Settings%\All Users\Application Data\~{random}
  • %Documents and Settings%\All Users\Application Data\~{random}r
  • %User Profile%\Application Data\Microsoft\Internet Explorer\Quick Launch\System Restore.lnk
  • %Desktop%\System Restore.lnk
  • %User Profile%\Start Menu\Programs\System Restore\System Restore.lnk
  • %User Profile%\Start Menu\Programs\System Restore\Uninstall System Restore.lnk

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %Desktop% is the current user's desktop, which is usually C:\Windows\Profiles\{user name}\Desktop on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Desktop on Windows NT, and C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003.)

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

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

It creates the following folders:

  • %User Profile%\Start Menu\Programs\System Restore

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

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnZoneCrossing = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonBadCertRecving = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
CertificateRevocation = "0"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1601 = "0"

(Note: The default value data of the said registry entry is "1".)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}e.com/britix
  • http://{BLOCKED}gs-503872.com/britix
  • http://{BLOCKED}2866.com/britix
  • http://{BLOCKED}94233.com/britix
  • http://{BLOCKED}20186.com/britix

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

Rogue Antivirus Routine

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 a certain website asking for sensitive information, such as credit card numbers.

When users agree to buy the software, it connects to the following URL to continue the purchase:

  • http://{BLOCKED}e.com/customers/buy.php
  • http://{BLOCKED}gs-503872.com/customers/buy.php
  • http://{BLOCKED}2866.com/customers/buy.php
  • http://{BLOCKED}4233.com/customers/buy.php
  • http://{BLOCKED}0186.com/customers/buy.php
  • http://{BLOCKED}e.com/customers/buy.php
  • http://{BLOCKED}gs-503872.com/customers/buy.php
  • http://{BLOCKED}2866.com/customers/buy.php
  • http://{BLOCKED}4233.com/customers/buy.php
  • http://{BLOCKED}0186.com/customers/buy.php

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.504.07

FIRST VSAPI PATTERN DATE:

17 Oct 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

Identify and terminate files detected as TROJ_FAKEAV.DFL

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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\Internet Settings
    • WarnOnZoneCrossing = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonBadCertRecving = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • CertificateRevocation = 0

Step 4

Restore this modified 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\Internet Settings\Zones\3
    • From: 1601 = 0
      To: 1601 = 1

Step 5

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. %User Profile%\Start Menu\Programs\System Restore

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. %Documents and Settings%\All Users\Application Data\{random}
%Documents and Settings%\All Users\Application Data\~{random}
%Documents and Settings%\All Users\Application Data\~{random}r
%User Profile%\Application Data\Microsoft\Internet Explorer\Quick Launch\System Restore.lnk
%Desktop%\System Restore.lnk

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAKEAV.DFL. 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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