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VBS_PICA.AH

October 08, 2012
 Analysis by: Michael Cabel
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • 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

File Size:

16,518 bytes

File Type:

VBS

Memory Resident:

Yes

Initial Samples Received Date:

08 Sep 2009

Payload:

Prevents execution of certain processes, Downloads files

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

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

06.426.01

FIRST VSAPI PATTERN DATE:

08 Sep 2009

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\Microsoft\Windows Scripting Host\Settings
    • Timeout = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ExplorerRun
    • system = %Windows%\.MS32DLL.dll.exe..VBs.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ExplorerRun
    • windos = wscript.exe %Windows%\boot.ini
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • MS32DLL = %Windows%\.MS32DLL.dll.exe..VBs.
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • nvdll32 = wscript.exe /E:vbs %Windows%\boot.ini

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\Explorer\Advanced
    • From: ShowSuperHidden = 0
      To: 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoDriveTypeAutoRun = 0
      To: {Varies}

Step 5

Search and delete AUTORUN.INF files created by VBS_PICA.AH that contain these strings

[ Learn More ]
[autorun]
shell\Auto\command=
shellexecute= wscript.exe .MS32DLL.dll.exe..VBs

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.


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