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 files:
- %Application Data%\netfilter.sys → detected as Rootkit.Win64.FETNILTER.A
- {malware path}\c.xalm → contains code to register netfilter as a driver service; deleted after use
It adds the following processes:
- To register %Application Data%\netfilter.sys as driver service:
- "%System%\regini.exe" c.xalm
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Other Details
This Trojan does the following:
- It adds and runs the following services:
- ServiceName: netfilter
- ImagePath: \??\%Application Data%\netfilter.sys
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
Step 1
Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:
- Troj.Win32.TRX.XXPE50FFF045P0005
Step 2
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.
Step 3
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 4
Restart in Safe Mode
[ Learn More ]
[ back ]
To restart in Safe Mode:
• For Windows 7 and Windows Server 2008 (R2) users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.
- On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.
• For Windows 8, Windows 8.1, and Windows Server 2012 users
- Access the Charms bar by moving your mouse pointer to the upper right corner of the screen.
- Move your mouse pointer down and click Settings>Change your PC Settings.
- In the left panel, click General.
- In the right panel, scroll down to the bottom to find the Advanced startup section, then click the Restart now button and wait for the system to restart.
- In the Advanced Startup menu, click Troubleshoot>Advanced Options>Startup Settings>Restart and wait for the system to restart.
- In the Startup Settings menu, press 4 to enable safe mode.
• For Windows 10 users
- Press Windows logo key + I on your keyboard to open Settings. If that doesn't work, select the Start button, then select Settings.
- Select Update & Security > Recovery.
- Under Advanced startup, select Restart now.
- After your PC restarts to the Choose an option screen, select Troubleshoot > Advcanced options > Startup settings > Restart.
- After your PC restarts, you'll see a list og options. Select 4 or press F4 to start your PC in Safe Mode.
Step 5
Disable this malware service
[ Learn More ]
[ back ]
Disabling a Malware Service
To disable a service:
- Open a command prompt window:
» For Windows 7 and Windows 2008 (R2) users, click the Start button, type cmd in the Search input field, and press Enter.
» For Windows 8, Windows 8.1 and Windows Server 2012 (R2) users, right-click on the lower-left corner of the screen,click Command Prompt.
» For Windows 10 users, right-click on the lower-left corner of the screen,click Run, type cmd in the text box provided, and press Enter. - At the command prompt, type the following:
NET STOP netfilter - Press Enter. A message should indicate that the service has been stopped successfully.
- Close the command prompt window.
Step 6
Delete this registry key
[ Learn More ]
[ back ]
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\netfilter
To delete the registry key this malware/grayware created:
- Open Registry Editor.
» For Windows 7 and Windows Server 2008 (R2) users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, Windows 10, and Windows Server 2012 (R2) users, right-click on the lower left corner of the screen, click Run, type regedit in the text box provided, and then press Enter. HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>Services>netfilter - Close Registry Editor.
Step 7
Search and delete this file
[ Learn More ]
[ back ]
There may be some files that are hidden. Please make sure you check the
Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
- %Application Data%\netfilter.sys
To manually delete a malware/grayware file from an affected system:
•For Windows 7, Windows Server 2008 (R2), Windows 8, Windows 8.1, Windows 10, and Windows Server 2012 (R2):
- Open a Windows Explorer window.
- For Windows 7 and Server 2008 (R2) users, click Start>Computer.
- For Windows 8, 8.1, 10, and Server 2012 (R2) users, right-click on the lower-left corner of the screen,then click File Explorer.
- In the Search Computer/This PC input box, type:
- %Application Data%\netfilter.sys
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: Read the following Microsoft page if these steps do not work on Windows 7 and Windows Server 2008 (R2).
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.FETNILTER.A. 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.
