WORM_AUTORUN.ENW
Trojan:Win32/Ircbrute(Microsoft), Trojan.Win32.Ircbrute(Sunbelt), Trojan-Ransom.Win32.Blocker(Ikarus), Win32/Nomkesh.C worm(Eset)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
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
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 and executes them:
- %Application Data%\{random file name}.exe
(Note: %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 drops the following files:
- {Drive Letter}:\snkb00pt\Desktop.ini
- {Drive Letter}:\{folder name}.LNK - if the removable drive contains folder
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 file name} = ""%Application Data%\{random file name}.exe""
Propagation
This worm creates the following folders in all removable drives:
- {Drive Letter}:\snkb00pt
It drops the following copy(ies) of itself in all removable drives:
- {Drive Letter}:\snkb00pt\snkb00pt.exe
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:
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
Other Details
This worm connects to the following possibly malicious URL:
- http://{BLOCKED}re.com/direct/24041216-b98.ls9s983
NOTES:
This worm drops shortcut files pointing to the copy of itself in removable drives. These dropped .LNK files use the names of the folders located on the said drives for their file names.
It then sets the attributes of the original folders to Hidden to trick the user into clicking the .LNK files.
SOLUTION
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
Restart in Safe Mode
Step 3
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 file name} = ""%Application Data%\{random file name}.exe""
- {random file name} = ""%Application Data%\{random file name}.exe""
Step 4
Search and delete this folder
- {Drive Letter}:\snkb00pt
Step 5
Search and delete these files
- {Drive Letter}:\snkb00pt\Desktop.ini
- {Drive Letter}:\{folder name}.LNK
Step 6
Search and delete AUTORUN.INF files created by WORM_AUTORUN.ENW that contain these strings
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
{Drive Letter}:\snkb00pt\snkb00pt.exe
I;.{garbage characters}
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_AUTORUN.ENW. 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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