VBS_AUTORUN.IHT
Troj/VBS-CC (Sophos), Trojan.VBS.Autorun.v (Kaspersky), Worm:VBS/Autorun.BT (Microsoft), VBS/Autorun.worm.aadz (NAI), Trojan.Malscript (Norton), VBS/Autorunner.C (Antivir)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Worm
Destructiveness: No
Encrypted:
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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
TECHNICAL DETAILS
184,508 bytes
VBS
10 May 2013
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 copies of itself into the affected system:
- %Program Files%\Common Files\System\Windows Update\wxz.dat
- %Application Data%\Microsoft\SYSTEM\cste
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)
It creates the following folders:
- %Program Files%\Common Files\System\Windows Update
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)
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\policies\
Explorer\Run
Updates = "%Windows%\svchost .exe" /e:VBScript.Encode "%Application Data%\Microsoft\SYSTEM\cste"""
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "dword:00000000"
HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\System
DisableCMD = "dword:00000000"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "dword:00000001"
(Note: The default value data of the said registry entry is dword:00000002.)
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- {removable drive letter}:\Microsoft.dat
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]
ShElLEXeCuTE=WScRiPt.EXe /e:VBScRIpt.eNcOdE miCroSoFt.dat
Dropping Routine
This worm drops the following files:
- %Windows%\svchost .exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
NOTES:
It drops the following shortcut pointing to its copy in all removable drive:
- -{removable drive letter}:\{user name}.lnk
The dropped copies of itself in removable drives are set to Hidden.