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TROJ_FAKEAV.WAJ

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 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 arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.

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:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Jun 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 copies of itself into the affected system and executes them:

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

It drops the following file(s)/component(s):

  • %Desktop%\Windows XP Restore.lnk
  • %Start Menu%\Programs\Windows XP Restore\Uninstall Windows XP Restore.lnk
  • %Start Menu%\Programs\Windows XP Restore\Windows XP Restore.lnk
  • %System Dir%\Documents and Settings\All Users\Application Data\{random characters}

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

It creates the following folders:

  • %Start Menu%\Programs\Windows XP Restore

(Note: %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu 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_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = %System Dir%\Documents and Settings\All Users\Application Data\{random}.exe

Other System Modifications

This Trojan adds the following registry entries:

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 key(s)/entry(ies) as part of its installation routine:

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.)

Download Routine

This Trojan connects to the following malicious URLs:

  • http://{BLOCKED}ant.org/dfrg/dfrg
  • http://{BLOCKED}attention.org/dfrg/dfrg
  • http://{BLOCKED}attention.org/dfrg/dfrgr
  • http://{BLOCKED}attention.org/404.php

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}ant.org/customers/buy.php

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

08.218.01

FIRST VSAPI PATTERN DATE:

11 Jun 2011

Step 1

Identify and terminate files detected as TROJ_FAKEAV.WAJ

[ 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 2

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}=%System Dir%\Documents and Settings\All Users\Application Data\{random}.exe
  • 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 3

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 4

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. %Start Menu%\Programs\Windows XP Restore

Step 5

Search and delete these files

[ 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. %Desktop%\Windows XP Restore.lnk
%Start Menu%\Programs\Windows XP Restore\Uninstall Windows XP Restore.lnk
%Start Menu%\Programs\Windows XP Restore\Windows XP Restore.lnk
%System Dir%\Documents and Settings\All Users\Application Data\{random characters}

Step 6

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