TROJ_NEBULER.SMK
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: No
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 does not have any propagation routine.
It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.
It opens a hidden Internet Explorer window.
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 non-malicious files:
- %Current Directory%\{malware name}.bat – used to delete the executed malware and batch file
- %System%\passed.txt – non malicious text file
(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 itself into the following processes as part of its memory residency routine:
- IEXPLORE.EXE
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
MSSMSGS = "rundll32 {malware path and filename},SpXapbF"
Other System Modifications
This Trojan adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
Data = {dword value}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
LSTV = {hex values}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
BSTV = {hex values}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
MSLIST = {hex values}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
Brnd = {dword value}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
SSTV = {hex values}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSSMGR
SCLIST = {hex values}
Propagation
This Trojan does not have any propagation routine.
Download Routine
This Trojan connects to the following malicious URLs:
- http://{BLOCKED}fseher.net/img/cmd.php
- http://{BLOCKED}ft.net/img/cmd.php
Other Details
This Trojan opens a hidden Internet Explorer window.
NOTES:
The downloaded file is saved in %User Temp% directory.
However, during testing, no files were downloaded.
It creates the following mutex to ensure that only one instance of itself is running in memory:
- m3d5rt10
Retry
del "c:\_virus\winwki32.dll"
if exist "c:\_virus\winwki32.dll" goto Retry
del "c:\_virus\winwki32.bat"
exit
This malware does not have rootkit capabilities.
This malware does not exploit any vulnerability.
SOLUTION
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
Scan your computer with your Trend Micro product and note files detected as TROJ_NEBULER.SMK
Step 3
Restart in Safe Mode
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
- MSSMSGS = "rundll32 {malware path and filename},SpXapbF"
- MSSMSGS = "rundll32 {malware path and filename},SpXapbF"
Step 5
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\SOFTWARE\Microsoft
- MSSMGR
- MSSMGR
Step 6
Search and delete these files
- %Current Directory%\{malware name}.bat
- %System%\passed.txt
Step 7
Search and delete the file detected as TROJ_NEBULER.SMK
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_NEBULER.SMK. 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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