WORM_WIPMBR.A
Trojan:Win64/WipMBR.A (Microsoft), W32.DistTrack (Symantec), W64/DistTrack (NAI), Troj/MBRWipe-C (Sophos), Trojan.Win32.Generic!BT (Sunbelt), Win64/DistTrack.A trojan (NOD32)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: Yes
Encrypted:
In the wild: Yes
OVERVIEW
Propagates via network shares, Downloaded from the Internet
This is the Trend Micro detection for worm that replaces the master boot record (MBR), limiting access to the affected computer. It may also cause systems to crash, rendering your computer useless.
This worm arrives by accessing affected shared networks. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It connects to a website to send and receive information.
TECHNICAL DETAILS
Compromises system security
Arrival Details
This worm arrives by accessing affected shared networks.
It 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 a copy of itself in the following folders using different file names:
- %System%\trksvr.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It drops the following component file(s):
- {Malware Path}\f1.inf
- {Malware Path}\f2.inf
- %Windows%\inf\netfb318.pnf
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
Autostart Technique
This worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\TrkSvr
ImagePath = "%System Root%\System32\svchost.exe -k NetworkService"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\drdisk
ImagePath = "%System%\Drivers\drdisk.sys"
Other System Modifications
This worm modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\LanmanWorkstation
DependOnService = "Browser MRxSmb10 MRxSmb20 NSI TrkSvr"
(Note: The default value data of the said registry entry is Browser MRxSmb10 MRxSmb20 NSI.)
Propagation
This worm uses the following file names for the copies it drops into shared networks:
- sc.exe
- findstr.exe
- caclsrv.exe
- certutl.exe
- clean.exe
- ctrl.exe
- dfrag.exe
- dnslookup.exe
- dvdquery.exe
- event.exe
- extract.exe
- findfile.exe
- fsutl.exe
- gpget.exe
- iissrv.exe
- ipsecure.exe
- msinit.exe
- netx.exe
- ntdsutl.exe
- ntfrsutil.exe
- ntnw.exe
- power.exe
- rdsadmin.exe
- regsys.exe
- routeman.exe
- rrasrv.exe
- sacses.exe
- sfmsc.exe
- sigver.exe
- smbinit.exe
- wcscript.exe
Backdoor Routine
This worm connects to the following websites to send and receive information:
- http://{BLOCKED}.{BLOCKED}.252.19/ajax_modal/modal/data.asp
SOLUTION
9.200
9.330.01
17 Aug 2012
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
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 3
Scan your computer with your Trend Micro product and note files detected as WORM_WIPMBR.A
Step 4
Restart in Safe Mode, and then 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\SYSTEM\CurrentControlSet\services
- drdisk
- drdisk
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
- TrkSvr
- TrkSvr
Step 5
Search and delete these files
- {Malware Path}\f1.inf
- {Malware Path}\f2.inf
- %Windows%\inf\netfb318.pnf
Step 6
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\LanmanWorkstation
- From: DependOnService = "Browser MRxSmb10 MRxSmb20 NSI TrkSvr"
To: DependOnService = "Browser MRxSmb10 MRxSmb20 NSI"
- From: DependOnService = "Browser MRxSmb10 MRxSmb20 NSI TrkSvr"
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_WIPMBR.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.
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