Threat Encyclopedia

TROJ_KILLMBR.DS

Publish date: March 21, 2013

ANALYSIS BY

Jaime Benigno Reyes


PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type:Trojan

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet


This malware is involved in the Master Boot Record (MBR) wiper outbreak that targeted users in South Korea during March of 2013. It drops and executes malware on affected systems, including a destructive payload that wipes the affected system's MBR. Users affected by this malware may find their systems freezing, shutting down, and unable to run.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Mar 2013

Payload:

Others, Displays graphics/image

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 component file(s):

  • %User Temp%\alg.exe - PuTTY client
  • %User Temp%\conime.exe - PuTTY client
  • %User Temp%\~pr1.tmp - detected by Trend Micro as UNIX_KILLMBR.A

(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 and 7.)

It drops and executes the following files:

  • %User Temp%\AgentBase.exe - detected by Trend Micro as TROJ_KILLMBR.SM

(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 and 7.)

NOTES:

This Trojan searches the system for the configuration files of two SSH clients:

  • Felix Deimel's mRemote: %AppDataLocal%\Felix_Deimel\mRemote\confCons.xml
  • VanDyke's Secure CRT: %Application Data%\VanDyke\Config\Sessions

If a configuration file is found, it parses it and looks for a user with root privileges on a remote system and extracts connection information.

Using the connection information, it connects to the remote system using the dropped Putty clients. Once connection has been established, it uploads and execute the file %User Temp%\~pr1.tmp as /tmp/cups on the remote system.

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.812.03

FIRST VSAPI PATTERN DATE:

23 Mar 2013

VSAPI OPR PATTERN File:

9.813.00

VSAPI OPR PATTERN Date:

24 Mar 2013

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

Remove the malware/grayware file dropped/downloaded by TROJ_KILLMBR.DS

Step 3

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %User Temp%\alg.exe
  • %User Temp%\conime.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_KILLMBR.DS. 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.


Did this description help? Tell us how we did.

Featured Stories

Connect with us on