Analysis by: Kathleen Notario
ALIASES:

Rootkit.Boot.Wistler.a (Kaspersky); Whistler!mbr (Mcafee); Troj/MBRoot-K (Sophos); Wistler.A (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This is Trend Micro's detection for an infected Master Boot Record (MBR) modified by another malware.

  TECHNICAL DETAILS

File Size: 512 bytes
File Type: BOOT
Initial Samples Received Date: 03 Aug 2011

NOTES:
This is Trend Micro's detection for a system's infected Master Boot Record (MBR) that has been modified by another malware.

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 8.331.00
VSAPI OPR PATTERN Date: 03 Aug 2011

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

Restore your system’s Master Boot Record (MBR)

To restore your system's Master Boot Record (MBR):

  1. Insert your Windows Installation CD into your CD-ROM drive or the USB flash drive then restart your computer.
  2. Press the restart button of your computer.
  3. When prompted, press any key to boot from the CD.
  4. When prompted on the Main Menu, type r to enter the Recovery Console.
    (For Windows 2000 users: After pressing r, type c to choose the Recovery Console on the repair options screen.)
  5. When prompted, type your administrator password to log in.
  6. Once logged in, type the drive that contains Windows in the command prompt that appears, and then press Enter.
  7. Type the following then press Enter:
    fixmbr {affected drive}
    (Note: The affected drive is the bootable drive that this malware/grayware has affected. If no device is specified, the MBR will be written in the primary boot drive.)
  8. Type exit to restart the system.

Step 3

Scan your computer with your Trend Micro product to delete files detected as BOOT_WHISLER.SMU. 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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