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TROJ_FAKEAV.FUQ

October 08, 2012
 Analysis by: Christopher Daniel So
 ALIASES:

Trojan:Win32/FakeSysdef (Microsoft), UltraDefraggerFraud (Symantec), Mal/FakeAV-EA (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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:

569,344 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Apr 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 files:

  • %Desktop%\Windows Repair.lnk
  • %Start Menu%\Programs\Windows Repair\Uninstall Windows Repair.lnk
  • %Start Menu%\Programs\Windows Repair\Windows Repair.lnk
  • %System Root%\Documents and Settings\All Users\Application Data\16965428
  • %System Root%\Documents and Settings\All Users\Application Data\16965428.exe

(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.. %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 filename}.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:

  • %Start Menu%\Programs\Windows Repair

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

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = "/{hq:/s`s:/ogn:/uyu:/dyd:/c`u:/bnl:/ble:/sdf:/lrh:/iul:/iulm:/fhg:/clq:/kqf:/`wh:/lqf:/lqdf:/lnw:/lq2:/l2t:/v`w:/rbs:"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Attachments
SaveZoneInformation = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop
NoChangingWallPaper = "1"

HKEY_CURRENT_USER\Software
75fa38b7-8b94-4995-ad32-52e938867954 = ""

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Download
CheckExeSignatures = "no"

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

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.112.10

FIRST VSAPI PATTERN DATE:

22 Apr 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

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
    • 75fa38b7-8b94-4995-ad32-52e938867954 =
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random filename}=%System Root%\Documents and Settings\All Users\Application Data\{random filename}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
    • LowRiskFileTypes=/{hq:/s`s:/ogn:/uyu:/dyd:/c`u:/bnl:/ble:/sdf:/lrh:/iul:/iulm:/fhg:/clq:/kqf:/`wh:/lqf:/lqdf:/lnw:/lq2:/l2t:/v`w:/rbs:
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
    • NoChangingWallPaper=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments
    • SaveZoneInformation=1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • DisableTaskMgr=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • DisableTaskMgr=1

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\Internet Explorer\Download
    • From: CheckExeSignatures=no
      To: CheckExeSignatures=yes

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 Repair.lnk
  • %System Root%\Documents and Settings\All Users\Application Data\16965428
  • %System Root%\Documents and Settings\All Users\Application Data\16965428.exe
  • %System Root%\Documents and Settings\All Users\Application Data\16965428
  • %System Root%\Documents and Settings\All Users\Application Data\16965428.exe

    • Note: To do a search for the following files, right-click Start then click Search... or Find..., depending on the version of Windows you are running. For each file to be deleted, type its file name in the Named input box. In the Look In drop-down list, select My Computer, then press Enter.
  • Once located, select the file then press SHIFT+DELETE to permanently delete the file.
  • Repeat the said steps for all files listed.

    • Step 6

    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. %Start Menu%\Programs\Windows Repair

    Step 7

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