PE_WAMGIN.A-O
Virus:Win32/Wamgin.A (Microsoft); Generic BackDoor.k (McAfee); W32.Wamgin (Symantec); PAK:ASPack, Backdoor.Win32.VB.bgf (Kaspersky); Backdoor.Vb.ARG (FSecure)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
38,400 bytes
EXE
Yes
25 Sep 2012
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Autostart Technique
This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe %Windows%\SMSS.EXE"
(Note: The default value data of the said registry entry is Explorer.exe.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%Windows%\SMSS.EXE"
(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)
Other System Modifications
This Trojan deletes the following files:
- %Temp%\scs1.tmp
- %Temp%\scs2.tmp
(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)
It deletes the following folders:
- %Windows%\SMSS.EXE
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
Dropping Routine
This Trojan drops the following files:
- %System Root%\dntboot.bin
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
This report is generated via an automated analysis system.
SOLUTION
9.200
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
Identify and delete files detected as PE_WAMGIN.A-O using either the Startup Disk or Recovery Console
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: Shell = "explorer.exe %Windows%\SMSS.EXE"
To: Shell = ""Explorer.exe""
- From: Shell = "explorer.exe %Windows%\SMSS.EXE"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Userinit = "%System%\userinit.exe,%Windows%\SMSS.EXE"
To: Userinit = ""%Windows%\system32\userinit.exe,""
- From: Userinit = "%System%\userinit.exe,%Windows%\SMSS.EXE"
Step 4
Search and delete this file
- %System Root%\dntboot.bin
Step 5
Scan your computer with your Trend Micro product to delete files detected as PE_WAMGIN.A-O. 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.
Step 6
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %Temp%\scs1.tmp
- %Temp%\scs2.tmp
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