TROJ_DELF.BN
TrojanDropper:Win32/Delf.BN, VirTool:Win32/DelfInject.gen!AH (Microsoft); BackDoor-AMQ (McAfee); Backdoor.Beasty.dr (Symantec); Trojan-Dropper.Win32.Small.amw (Kaspersky); RiskTool.Win32.ProcessPatcher.Nor!cobra (v) (not malicious) (Sunbelt); MemScan:Backdoor.Darkmoon.52 (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.
It disables Task Manager, Registry Editor, and Folder Options.
TECHNICAL DETAILS
552,862 bytes
EXE
Yes
02 Nov 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 adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{42CE4021-DE03-E3CC-EA32-40BB12E6015D}
StubPath = "%System%\mskndn.com"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\SAM\A
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{42CE4021-DE03-E3CC-EA32-40BB12E6015D}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = "No"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
COM Service = "%Windows%\msagent\msvsui.com"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess
Start = "4"
(Note: The default value data of the said registry entry is 2.)
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
COM Service = "%Windows%\msagent\msvsui.com"
Dropping Routine
This Trojan drops the following files:
- %User Temp%\patriotas1.exe
- %User Temp%\Cartas Magicas.exe
- server.exe
- osum.exe
- %User Temp%\Cartas Magicas.exe_
- %Windows%\msagent
- %Windows%\svchost.exe
- %System%\mskndn.com
- %Windows%\msagent\msvsui.com
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Restart in Safe Mode
Step 3
Enable Registry Editor, Task Manager, and Folder options
Step 4
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\SAM
- A
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
- {42CE4021-DE03-E3CC-EA32-40BB12E6015D}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer
- Run
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer
- Run
Step 5
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{42CE4021-DE03-E3CC-EA32-40BB12E6015D}
- StubPath = "%System%\mskndn.com"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- Check_Associations = "No"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
- COM Service = "%Windows%\msagent\msvsui.com"
Step 6
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\ControlSet001\Services\SharedAccess
- From: Start = "4"
To: Start = ""2""
- From: Start = "4"
Step 7
Search and delete these files
- %User Temp%\patriotas1.exe
- %User Temp%\Cartas Magicas.exe
- server.exe
- osum.exe
- %User Temp%\Cartas Magicas.exe_
- %Windows%\msagent
- %Windows%\svchost.exe
- %System%\mskndn.com
- %Windows%\msagent\msvsui.com
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DELF.BN. 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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