WORM_VOBFUS.ZTN
Worm:Win32/Vobfus.NN (Microsoft), a variant of Win32/VBObfus.LP trojan (Nod32), Troj/Agent-AAOL (Sophos), Trojan horse VB2.KQC (AVG)
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 by connecting affected removable drives to a system.
TECHNICAL DETAILS
286,720 bytes
EXE
Yes
10 Mar 2013
Arrival Details
This worm arrives by connecting affected removable drives to a system.
Installation
This worm drops the following file(s)/component(s):
- {removable drive letter}:\x.mpeg
It drops the following copies of itself into the affected system:
- %User Profile%\{random}.exe
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
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\Run
{random} = "%User Profile%\{random}.exe /{random letter}"
Other System Modifications
This worm adds the following registry entries as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate\
AU
NoAutoUpdate = "1"
It modifies the following registry entries to hide files with Hidden 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(ies) of itself in all removable drives:
- {removable drive letter}:\{random file name}.exe
- {removable drive letter}:\Passwords.exe
- {removable drive letter}:\Porn.exe
- {removable drive letter}:\Secret.exe
- {removable drive letter}:\Sexy.exe
- {removable drive letter}:\{folder name}.exe
The said .INF file contains the following strings:
{garbage characters}
[autorun]
{garbage characters}
open={random}.eXE
{garbage characters}
ACTION={random number}
{garbage characters}
UsEaUTopLay=1
{garbage characters}
Other Details
This worm connects to the following possibly malicious URL:
- http://{BLOCKED}5.no-ip2.net:81
- http://{BLOCKED}I.no-ip2.net:81
- http://{BLOCKED}M.NO-IP2.NET:81
- http://{BLOCKED}r.ru
- http://{BLOCKED}g.su
- http://{BLOCKED}s.su
NOTES:
This worm searches for folders in all removable drives then drops copies of itself as {folder name}.exe.
It also uses the file names of files with the following extensions:
- .avi
- .bmp
- .doc
- .gif
- .jpe
- .jpg
- .mp3
- .mp4
- .mpg
- .png
- .tif
- .txt
- .wav
- .wma
- .wmv
- .xls
It then sets the attribute of the original file or folder to Hidden and System to trick users into thinking that the dropped copy is the legitimate file or folder.
SOLUTION
9.300
9.778.04
10 Mar 2013
9.779.00
11 Mar 2013
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Scan your computer with your Trend Micro product and note files detected as WORM_VOBFUS.ZTN
Step 3
Restart in Safe Mode
Step 4
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\CurrentVersion\Run
- {random} = "%User Profile%\{random}.exe /{random letter}"
- {random} = "%User Profile%\{random}.exe /{random letter}"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
- NoAutoUpdate = "1"
- NoAutoUpdate = "1"
Step 5
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: ShowSuperHidden = "1"
- From: ShowSuperHidden = "0"
Step 6
Search and delete this file
- {removable drive letter}:\x.mpeg
Step 7
Search and delete AUTORUN.INF files created by WORM_VOBFUS.ZTN that contain these strings
- {garbage characters}
- [autorun]
- {garbage characters}
- open={random}.eXE
- {garbage characters}
- ACTION={random number}
- {garbage characters}
- UsEaUTopLay=1
- {garbage characters}
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_VOBFUS.ZTN. 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.