WORM_FAILNUM.A
IM-Worm.Win32.Agent.pt (Kaspersky)
Windows
![](/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
80,896 bytes
EXE
Yes
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:
- %User Temp%\vshost32.exe
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Autostart Technique
This worm modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%User Temp%\vshost32.exe"
(Note: The default value data of the said registry entry is %System%\userinit.exe.)
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
BuildID = "d3adc0de"
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- {removable drive}\vshost.exe
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
Other Details
This worm connects to the following possibly malicious URL:
- http://fubar.{BLOCKED}ocks.cn:80/check.php?p1=12345&p2=USA
- http://win.{BLOCKED}ngcenter-org.com
- http://ns.{BLOCKED}o-net.com
SOLUTION
9.700
6.632.02
17 Nov 2009
6.633.00
17 Nov 2009
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
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 3
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Userinit = "%System%\userinit.exe,%User Temp%\vshost32.exe"
To: Userinit = %System%\userinit.exe
- From: Userinit = "%System%\userinit.exe,%User Temp%\vshost32.exe"
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 NT\CurrentVersion\Winlogon
- BuildID = "d3adc0de"
- BuildID = "d3adc0de"
Step 5
Search and delete AUTORUN.INF files created by WORM_FAILNUM.A that contain these strings
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_FAILNUM.A. 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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