TROJ_AGENT_025880.TOMB
Backdoor:Win32/Simda.gen!B (Microsoft); Backdoor.Trojan (Symantec); Backdoor.Win32.Shiz.btsf (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.7340751 (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
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 adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userinit = "{malware path and file name}"
It 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,{malware path and file name},"
(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)
Other System Modifications
This Trojan adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
f0bdff95 = "{random characters}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
run = "{malware path and file name}"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
System = "{malware path and file name}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = "{malware path and file name}"
This report is generated via an automated analysis system.
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
Identify and delete files detected as TROJ_AGENT_025880.TOMB using either the Startup Disk or Recovery Console
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
- userinit = "{malware path and file name}"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- f0bdff95 = "{random characters}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- run = "{malware path and file name}"
Step 4
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
- System = "{malware path and file name}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- load = "{malware path and file name}"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: userinit = "%System%\userinit.exe,{malware path and file name},"
To: userinit = ""%Windows%\system32\userinit.exe,""
- From: userinit = "%System%\userinit.exe,{malware path and file name},"
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_AGENT_025880.TOMB. 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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