TROJ_KILLMBR.DZ

 Analysis by: Anthony Joe Melgarejo

 ALIASES:

Trojan:Win32/Killav.GZ (Microsoft), Trojan Horse (Symantec), Troj/MBRKill-A (Sophos), Gen:Trojan.Heur.JP.dq0@aGAAq2cG (Bitdefender), Win.Trojan.Agent-257543 (ClamAV), W32/Kast.A!tr (Fortinet), Trojan-PWS.Win32.Fareit (Ikarus), OScope.Trojan.KillMBR.2113 (VBA32)

 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: No

  • In the wild: Yes

  OVERVIEW


This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size:

49,152 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

23 Mar 2013

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan drops the following files:

  • %Program Files%\Hauri\SiteServer\vismsupdate\vms1014.zip - (contains OthDown.exe) detected as TROJ_KILLMBR.SM

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It drops the following non-malicious files:

  • %Program Files%\Hauri\SiteServer\vismsupdate\update.zip

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Other System Modifications

This Trojan deletes the following files:

  • %Program Files%\hauri\SiteClient\VrDown.exe
  • %Program Files%\Hauri\SiteServer\VrPatch.exe
  • %Program Files%\Hauri\SiteServer\ptUpdate.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\Software\VMS\
3.0\SiteServer\General
CenterServer = "hahaha"

(Note: The default value data of the said registry entry is "{Software default value}".)

HKEY_LOCAL_MACHINE\Software\VMS\
3.0\SiteServer\CfgInfo
ISMS = "56be65cd"

(Note: The default value data of the said registry entry is "{Software default value}".)

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • vrfwsvc.exe
  • vrptsvc.exe
  • vrscan.exe
  • hpcsvc.exe
  • hsvcmod.exe
  • vrfwsock.exe
  • vrfwsvc.exe
  • vrmonnt.exe
  • vrrepair.exe
  • vrmonsvc.exe
  • hsvcmod.exe
  • hpcsvc.exe

NOTES:

It drops file to a certain security software update folder. Therefore, when the said software updates, the dropped file (TROJ_KILLMBR.SM) is executed.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.818.04

FIRST VSAPI PATTERN DATE:

23 Mar 2013

VSAPI OPR PATTERN File:

9.819.00

VSAPI OPR PATTERN Date:

23 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 malware/grayware files dropped/downloaded by TROJ_KILLMBR.DZ

    • TROJ_KILLMBR.SM

Step 3

Restore this modified registry value

[ Learn More ]

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\Software\VMS\3.0\SiteServer\General
    • From: CenterServer = "hahaha"
      To: CenterServer = "{Software default value}"
  • In HKEY_LOCAL_MACHINE\Software\VMS\3.0\SiteServer\CfgInfo
    • From: ISMS = "56be65cd"
      To: ISMS = "{Software default value}"

Step 4

Search and delete this file

[ Learn More ]
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.
  • %Program Files%\Hauri\SiteServer\vismsupdate\update.zip
  • %Program Files%\Hauri\SiteServer\vismsupdate\vms1014.zip

Step 5

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

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Program Files%\hauri\SiteClient\VrDown.exe
  • %Program Files%\Hauri\SiteServer\VrPatch.exe
  • %Program Files%\Hauri\SiteServer\ptUpdate.exe


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