TROJ_KILLMBR.EG
W32/KillMBR.C!tr (Fortinet), W32/Trojan3.AMWR (F-Prot)
Windows
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: Yes
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.
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 files:
- %User Temp%\ns{Random 4 characters).tmp\System.dll
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)
It creates the following folders:
- %User Temp%\ns{Random 4 Characters}.tmp
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)
Other Details
This Trojan does the following:
- Wipes Master Boot Record Data
- It overwrites the portion of the physical drives with null values
- Performs Shutdown
SOLUTION
Step 1
Restore your system's Master Boot Record (MBR)
To restore your system's Master Boot Record (MBR):
• On Windows 2000, XP, and Server 2003:
- Insert your Windows Installation CD into your CD drive then restart your computer.
- When prompted, press any key to boot from the CD.
- On the Main Menu, type r to enter the Recovery Console.
(Note for Windows 2000: After pressing r, type c to choose the Recovery Console on the repair options screen.) - Type the number that corresponds to the drive and folder that contains Windows (usually C:\WINDOWS) and press Enter.
- Type your Administrator password and press Enter.
- In the input box, type the following then press Enter:
fixmbr {affected drive} - Type exit and press Enter to restart the system normally.
• On Windows Vista, 7, and Server 2008:
- Insert your Windows Installation DVD into the DVD drive, then press the restart button on your computer.
- When prompted, press any key to boot from the DVD.
- Depending on your Windows Installation DVD, you might be required to choose the installation language. On the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Repair your computer.
- Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
- If the Startup Repair window appears, click Cancel, Yes, then Finish.
- In the System Recovery Options menu, click Command Prompt.
- In the Command Prompt window, type the following then press Enter:
BootRec.exe /fixmbr - Type exit and press Enter to close the Command Prompt window.
- Click Restart to restart your computer normally.
• On Windows 8, 8.1, and Server 2012:
- Insert your Windows Installation DVD in the DVD drive, then restart your computer.
- When prompted, press any key to boot from the DVD.
- Depending on your Windows Installation DVD, you might be required to select the keyboard layout. Then on the Windows Setup window, choose your language, locale, and input method. Click Next, then click Repair your computer.
- Click Troubleshoot>Advanced Options>Command Prompt.
- In the Command Prompt window, type the following then press Enter:
BootRec.exe /fixmbr - Type exit and press Enter to close the Command Prompt window.
- Click Continue to restart the system normally.
Step 2
Before doing any scans, Windows XP, Windows Vista, and Windows 7 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
Search and delete these folders
- %User Temp%\ns{Random 4 Characters}.tmp
Step 5
Scan your computer with your Trend Micro product to delete files detected as TROJ_KILLMBR.EG. 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 the following Trend Micro Support pages for more information:
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