BKDR_BIFROSE.FSZ
Trojan.Win32.Generic!BT (Sunbelt)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It deletes itself after execution.
TECHNICAL DETAILS
694,476 bytes
EXE
Yes
14 May 2012
Arrival Details
This backdoor 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 backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\.Net CLR\Parameters
Other System Modifications
This backdoor adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
.Net CLR = ".Net CLR,_CHAR(0x15)_?_CHAR(0x12)_2088763392,???208876334194304,?????_CHAR(0x12)_"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.Net CLR\Parameters
ServiceDll = "%System%\9c5f.dll"
Dropping Routine
This backdoor drops the following files:
- %System%\9c5f.dll
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Other Details
This backdoor deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.200
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
Restart in Safe Mode
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\.Net CLR
- Parameters
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
- .Net CLR = ".Net CLR,_CHAR(0x15)_?_CHAR(0x12)_2088763392,???208876334194304,?????_CHAR(0x12)_"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.Net CLR\Parameters
- ServiceDll = "%System%\9c5f.dll"
Step 5
Search and delete this file
- %System%\9c5f.dll
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BIFROSE.FSZ. 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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