WORM_KELIHOS.FM
Backdoor:Win32/Kelihos.F(Microsoft), W32/Kelihos.BQGD!tr(Fortinet), a variant of Win32/Kryptik.BQSE trojan(Eset)
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: Worm
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This worm 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 worm 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 worm drops the following files:
- {Drive Letter}:\Shortcut to {random file name}.lnk
- {Drive Letter}:\{Folder name}.lnk - if folder exists
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random parameter 1}{random parameter 2} = "{malware path and file name}"
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
DefaultCompressedRecord = "{random value}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
RecordModifiedMax = "{random value}=="
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
FlagsModifiedValid = "0"
HKEY_CURRENT_USER\Software\TansuTCP
ActiveModifiedTheme = "{random value}"
HKEY_CURRENT_USER\Software\TansuTCP
SizeCompletedValid = "{random value}=="
HKEY_CURRENT_USER\Software\TansuTCP
InfoPlayedCurrent = "0"
Propagation
This worm drops the following copy(ies) of itself in all removable drives:
- {Drive Letter}:\{random file name}.exe
Other Details
This worm connects to the following possibly malicious URL:
- {BLOCKED}.{BLOCKED}.21.170/login.htm
- {BLOCKED}.{BLOCKED}.220.200/search.htm
NOTES:
The dropped copy, {random file name} in removable drives can be any of the following:
- click
- game
- hentai
- installer
- password
- porn
- run
- sas
- screensaver
It drops shortcut files pointing to the copy of itself in removable drives. These dropped .LNK files use the names of the folders located on the said drives for their file names. It then sets the attributes of the original folders to Hidden to trick the user into clicking the .LNK files.
The auto-run registry, {random parameter 1} can be any of the following:
- Updater
- Checker
- Notifyer
- Saver
- Verifyer
- Informer
The auto-run registry, {random parameter 2} can be any of the following:
- CrashReport
- Database
- Desktop
- Icon
- Media
- Network
- Time
- Tray
- Video
For example:
- CrashReportUpdater
- NetworkVerifyer
- TrayNotifyer
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 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\Explorer\Advanced
- DefaultCompressedRecord = "{random value}"
- DefaultCompressedRecord = "{random value}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- RecordModifiedMax = "{random value}=="
- RecordModifiedMax = "{random value}=="
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- FlagsModifiedValid = "0"
- FlagsModifiedValid = "0"
- In HKEY_CURRENT_USER\Software\TansuTCP
- ActiveModifiedTheme = "{random value}"
- ActiveModifiedTheme = "{random value}"
- In HKEY_CURRENT_USER\Software\TansuTCP
- SizeCompletedValid = "{random value}=="
- SizeCompletedValid = "{random value}=="
- In HKEY_CURRENT_USER\Software\TansuTCP
- InfoPlayedCurrent = "0"
- InfoPlayedCurrent = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- {random parameter 1}{random parameter 2} = "{malware path and file name}"
- {random parameter 1}{random parameter 2} = "{malware path and file name}"
Step 4
Search and delete this file
- {Drive Letter}:\Shortcut to {random file name}.lnk
- {Drive Letter}:\{Folder name}.lnk
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_KELIHOS.FM. 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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