TROJ_COMFOO.A
Windows 2000, XP, Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.
It injects its dropped file/component to specific processes.
It opens a hidden Internet Explorer window.
It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
It deletes itself after execution.
TECHNICAL DETAILS
131,072 bytes
EXE
No
20 May 2011
Drops files, Compromises system security
Arrival Details
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It may be downloaded by other malware/grayware/spyware from remote sites.
It may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This Trojan drops the following files:
- %System%\odbm.dll - BKDR_COMFOO.A
- %System%\msobj.sys - RTKT_COMFOO.A
(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 injects its dropped file/component to the following processes:
- Iexplore.exe
Autostart Technique
This Trojan registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
ImagePath = "%System%\msobj.sys"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
Type = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
Start = "3"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
DisplayName = "msobj"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj\Security
Security = "{hex values}"
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Netman
Start = "2"
(Note: The default value data of the said registry entry is 3.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Netman\Parameters
ServiceDll = "%System%\odbm.dll"
(Note: The default value data of the said registry entry is %System%\netman.dll.)
Backdoor Routine
This Trojan opens a hidden Internet Explorer window.
Dropping Routine
This Trojan executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.
Other Details
This Trojan deletes itself after execution.
SOLUTION
8.900
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 3
Delete this registry key
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\SYSTEM\CurrentControlSet\Services
- msobj
- msobj
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\SYSTEM\CurrentControlSet\Services\Netman
- From: Start = 2
To: Start = 3
- From: Start = 2
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netman\Parameters
- From: ServiceDll = %System%\odbm.dll
To: ServiceDll = %System%\netman.dll
- From: ServiceDll = %System%\odbm.dll
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_COMFOO.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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