WORM_AUTORUN.BKG
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
However, as of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
Arrival Details
This worm arrives via removable drives.
It 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 non-malicious files:
- %System%\{random characters}\cnvpe.fne
- %System%\{random characters}\dp1.fne
- %System%\{random characters}\eAPI.fne
- %System%\{random characters}\HtmlView.fne
- %System%\{random characters}\internet.fne
- %System%\{random characters}\krnln.fnr
- %System%\{random characters}\RegEx.fnr
- %System%\{random characters}\shell.fne
- %System%\{random characters}\spec.fne
- %User Temp%\E_N4\cnvpe.fne
- %User Temp%\E_N4\dp1.fne
- %User Temp%\E_N4\eAPI.fne
- %User Temp%\E_N4\HtmlView.fne
- %User Temp%\E_N4\internet.fne
- %User Temp%\E_N4\krnln.fnr
- %User Temp%\E_N4\shell.fne
- %User Temp%\E_N4\spec.fne
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
It drops the following copies of itself into the affected system:
- %System%\{random characters}\{Random characters}.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It creates the following folders:
- %System%\{random characters}
- %User Temp%\E_N4
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
Autostart Technique
This worm drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:
- {malware file name}.lnk
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- Recycle.exe
It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.
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]
open=Recycle.exe
shell\1={random characters}
shell\1\Command=Recycle.exe
shell\2\={random characters}
shell\2\Command=Recycle.exe
shellexecute=Recycle.exe
Other Details
This worm connects to the following possibly malicious URL:
- www.{BLOCKED}.{BLOCKED}n.com
However, as of this writing, the said sites are inaccessible.
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
Terminate a process file/s detected as WORM_AUTORUN.BKG
*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.
Step 3
Search and delete these folders
Step 4
Search and delete this file
Step 5
Search and delete AUTORUN.INF files created by WORM_AUTORUN.BKG that contain these strings
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.BKG. 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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