WORM_VBNA.SMTA
Worm:Win32/Vobfus.gen!E (Microsoft), Downloader-CJX.gen.o (Mcafee)
Windows 2000, XP, Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This worm arrives via removable drives. It may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware.
It drops copies of itself into all the removable drives connected to an affected system. 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
237,568 bytes
PE
Yes
22 Jan 2011
Arrival Details
This worm arrives via removable drives.
It may be downloaded by other malware/grayware/spyware from remote sites.
It may be dropped by other malware.
Installation
This worm drops the following copies of itself into the affected system:
- %User Profile%\{random name}.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.)
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 name} = %User Profile%\{random name}.exe /p
Other System Modifications
This worm 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 copies of itself into all the removable drives connected to an affected system.
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:
{garbage}
[AUtORUn]
{garbage}
ACTIOn=View Files
{garbage}
shELlEXecUTE={random name}.EXe
{garbage}
ICOn=%systeMroot%\systEM32\sheLL32.Dll,4
{garbage}
USEautOplay=1
{garbage}
Dropping Routine
This worm sets the attributes of its dropped file(s) to the following:
- Hidden
- System
- Read Only
Other Details
This worm does the following:
- Drops .LNK files that reference a copy of itself in removable drives. These dropped files use the names of the folders located on the said drives for their filenames. It then hides the original folders to further fool the users. In addition, it also uses the following names:
- Documents.lnk
- Music.lnk
- New Folder.lnk
- Passwords.lnk
- Pictures.lnk
- Video.lnk
- Attempts to resolve the following host names:
- {BLOCKED}ayer1253.com
- {BLOCKED}deoall.net
- {BLOCKED}diashares.org
SOLUTION
8.900
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
Scan your computer with your Trend Micro product and note files detected as WORM_VBNA.SMTA
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.
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run{random name} = %User Profile%\{random name}.exe /p
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.
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
ShowSuperHidden = 0
1
Step 6
Search and delete these files
{Removable Drive}\Music.lnk
{Removable Drive}\New Folder.lnk
{Removable Drive}\Passwords.lnk
{Removable Drive}\Pictures.lnk
{Removable Drive}\Video.lnk
{Removable Drive}\{folder name}.lnk
Step 7
Search and delete AUTORUN.INF files created by WORM_VBNA.SMTA that contain these strings
[AUtORUn]
{garbage}
ACTIOn=View Files
{garbage}
shELlEXecUTE={random name}.EXe
{garbage}
ICOn=%systeMroot%\systEM32\sheLL32.Dll,4
{garbage}
USEautOplay=1
{garbage}
Step 8
Scan your computer with your Trend Micro product to delete files detected as WORM_VBNA.SMTA. 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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