VBS_PICA.AH
Windows 2000, XP, Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm may arrive bundled with malware packages as a malware component. It may be dropped by other malware.
It modifies registry entries to hide files with System and Read-only attributes.
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
As of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
Arrival Details
This worm may arrive bundled with malware packages as a malware component.
It may be dropped by other malware.
Installation
This worm drops the following copies of itself into the affected system:
- %Windows%\boot.ini
- %Windows%\.MS32DLL.dll.exe..VBs
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ExplorerRun
system = %Windows%\.MS32DLL.dll.exe..VBs.
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ExplorerRun
windos = wscript.exe %Windows%\boot.ini
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
MS32DLL = %Windows%\.MS32DLL.dll.exe..VBs.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
nvdll32 = wscript.exe /E:vbs %Windows%\boot.ini
Other System Modifications
This worm adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows Scripting Host\Settings
Timeout = 0
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoDriveTypeAutoRun = 0
(Note: The default value data of the said registry entry is {Varies}.)
It modifies the following registry entries to hide files with System and Read-only attributes:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0
(Note: The default value data of the said registry entry is 1.)
Propagation
This worm drops the following copy of itself in all physical and removable drives:
- .MS32DLL.dll.exe..VBs
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
The said .INF file contains the following strings:
[autorun]
shell\Auto\command=
shellexecute= wscript.exe .MS32DLL.dll.exe..VBs
Process Termination
This worm terminates the following processes if found running in the affected system's memory:
- KVMonXP.kxp
- nod32kui.exe
- nod32krn.exe
- rfwsrv.exe
- RavMon.exe
- CCenter.exe
- Ravmond.exe
- KAVStart.EXE
- Rfw.exe
- KavRFW.exe
- 360Tray.exe
Download Routine
This worm accesses the following websites to download files:
- http://cnzz.go2.{BLOCKED}n.com/gz.exe
- http://cnzz.go2.{BLOCKED}n.com/ls.exe
- http://{BLOCKED}.{BLOCKED}.0.1/00/ca.exe
It saves the files it downloads using the following names:
- %Windows%\boot6.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
As of this writing, the said sites are inaccessible.
Other Details
Based on analysis of the codes, it has the following capabilities:
- It sets the NoDriveTypeAutorun default values depending on the Operating System used, as follows:
- Microsoft Windows Server 2003 = 95
- Microsoft Windows XP = 91
- Microsoft Windows 2000 = 95
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
Restart in Safe Mode
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_CURRENT_USER\Software\Microsoft\Windows Scripting Host\Settings
- Timeout = 0
- Timeout = 0
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ExplorerRun
- system = %Windows%\.MS32DLL.dll.exe..VBs.
- system = %Windows%\.MS32DLL.dll.exe..VBs.
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ExplorerRun
- windos = wscript.exe %Windows%\boot.ini
- windos = wscript.exe %Windows%\boot.ini
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- MS32DLL = %Windows%\.MS32DLL.dll.exe..VBs.
- MS32DLL = %Windows%\.MS32DLL.dll.exe..VBs.
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- nvdll32 = wscript.exe /E:vbs %Windows%\boot.ini
- nvdll32 = wscript.exe /E:vbs %Windows%\boot.ini
Step 4
Restore this modified 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: ShowSuperHidden = 0
To: 1
- From: ShowSuperHidden = 0
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
- From: NoDriveTypeAutoRun = 0
To: {Varies}
- From: NoDriveTypeAutoRun = 0
Step 5
Search and delete AUTORUN.INF files created by VBS_PICA.AH that contain these strings
Step 6
Scan your computer with your Trend Micro product to delete files detected as VBS_PICA.AH. 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.
Did this description help? Tell us how we did.