TROJ_FORUCON.BMG
Trojan:Win32/Obfac (Microsoft); RDN/Ransom!eg (McAfee); Trojan-Ransom.Win32.Foreign.kvkv (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Crypt3.UAG (AVG)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
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 deletes itself after execution.
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.
Installation
This Trojan drops the following copies of itself into the affected system:
- %System%\blasfmon.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
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
chknhost = "%System%\blasfmon.exe"
Other System Modifications
This Trojan deletes the following files:
- %System Root%\81484.bat
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
7926A403841D130B56BDF8F7EA41AC1B
It adds the following registry entries:
HKEY_CURRENT_USER\Software\AppDataLow\
7926A403841D130B56BDF8F7EA41AC1B
Client = "{random values}"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
FaultCount = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
FaultTime = "14a81"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
FaultCount = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
FaultTime = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
CleanShutdown = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
SysTray
Services = "1f"
(Note: The default value data of the said registry entry is 1f.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
LogSessionName = "stdout"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
Active = "1"
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
ControlFlags = "1"
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi\ImapiSvc
Guid = "8107d8e9-e323-49f5-bba2-abc35c243dca"
(Note: The default value data of the said registry entry is 8107d8e9-e323-49f5-bba2-abc35c243dca.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi\ImapiSvc
BitNames = "{random characters}"
(Note: The default value data of the said registry entry is ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort.)
It deletes the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
IEAK\GroupPolicy\PendingGPOs
Dropping Routine
This Trojan drops the following files:
- %Temp%\j17byvxu.TMP
(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)
Other Details
This Trojan deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
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_CURRENT_USER\SOFTWARE\AppDataLow
- 7926A403841D130B56BDF8F7EA41AC1B
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- chknhost = "%System%\blasfmon.exe"
- In HKEY_CURRENT_USER\Software\AppDataLow\7926A403841D130B56BDF8F7EA41AC1B
- Client = "{random values}"
Step 5
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- FaultCount = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- FaultTime = "14a81"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- FaultCount = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- FaultTime = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- CleanShutdown = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\SysTray
- From: Services = "1f"
To: Services = ""1f""
- From: Services = "1f"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
- From: LogSessionName = "stdout"
To: LogSessionName = ""{random values}""
- From: LogSessionName = "stdout"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
- From: Active = "1"
To: Active = ""1""
- From: Active = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
- From: ControlFlags = "1"
To: ControlFlags = ""1""
- From: ControlFlags = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi\ImapiSvc
- From: Guid = "8107d8e9-e323-49f5-bba2-abc35c243dca"
To: Guid = ""8107d8e9-e323-49f5-bba2-abc35c243dca""
- From: Guid = "8107d8e9-e323-49f5-bba2-abc35c243dca"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi\ImapiSvc
- From: BitNames = "{random characters}"
To: BitNames = "" ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort""
- From: BitNames = "{random characters}"
Step 6
Search and delete this file
- %Temp%\j17byvxu.TMP
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_FORUCON.BMG. 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 8
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.
- %System Root%\81484.bat
Step 9
Restore these deleted registry keys/values from backup
*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- In HKEY_CURRENT_USER\Software\Microsoft\IEAK\GroupPolicy
- PendingGPOs
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