WORM_FAKEAV.BSF
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm 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.
TECHNICAL DETAILS
Arrival Details
This worm 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 worm drops the following non-malicious files:
- %User Profile%\Application Data\ANSAV_AIO\ANSAV.ini
- %User Temp%\cconfig.anv
- %User Temp%\config.anv
- %User Temp%\dbs.anv
- %User Temp%\main.log
(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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
It drops the following copies of itself into the affected system:
- %User Profile%\Application Data\ANSAV_AIO\ansavgl.exe
- %User Profile%\Application Data\ANSAV_AIO\ ANSAV.exe
- %User Temp%\ANSAV.exe
(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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
It creates the following folders:
- %User Profile%\Application Data\ANSAV_AIO
(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.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
An Software Lab = "%User Profile%\Application Data\ANSAV_AIO\ansavgl.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Ansav Guard = "%User Profile%\Application Data\ANSAV_AIO\ ANSAV.exe"
Download Routine
This worm connects to the following malicious URLs:
- http://{BLOCKED}te.ansav.com
Rogue Antivirus Routine
This worm 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.
NOTES:
It creates the following folders in physical, removable and network drives:
- ANSAV_AIO
- ANSAV_AIO\Plugins
It drops copies of itself in the said drives as the following files:
- ANSAV_AIO\agd32.sys
- ANSAV_AIO\anPdetector.dll
- ANSAV_AIO\ANSAV.exe
- ANSAV_AIO\arc.dll
- ANSAV_AIO\fixer.fx
- ANSAV_AIO\Plugins\DeepSlayer.dll
- ANSAV_AIO\Plugins\HiddenRevealer.dll
- ANSAV_AIO\Plugins\MalTrack.dll
- ANSAV_AIO\Plugins\Process Image Finder.dll
- ANSAV_AIO\Plugins\RegistryFX.dll
- ANSAV_AIO\Plugins\xscript.dll
- ANSAV_AIO\ste.dll
- ANSAV_AIO\vdb
SOLUTION
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 WORM_FAKEAV.BSF
- 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.
- 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
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\Run
- An Software Lab = %User Profile%\Application Data\ANSAV_AIO\ansavgl.exe
- An Software Lab = %User Profile%\Application Data\ANSAV_AIO\ansavgl.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Ansav Guard = %User Profile%\Application Data\ANSAV_AIO\ ANSAV.exe
- Ansav Guard = %User Profile%\Application Data\ANSAV_AIO\ ANSAV.exe
Step 4
Search and delete these folders
- %User Profile%\Application Data\ANSAV_AIO
- {drive letter}\ANSAV_AIO
Step 5
Search and delete these files
- %User Temp%\cconfig.anv
- %User Temp%\config.anv
- %User Temp%\dbs.anv
- %User Temp%\main.log
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_FAKEAV.BSF. 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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