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O97M_TRISTATE.A

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

  TECHNICAL DETAILS

File Size:

1,656,832 bytes

File Type:

PPT

Initial Samples Received Date:

28 Dec 2011

Arrival Details

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

Other System Modifications

This file infector modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Office\8.0\Excel\
Microsoft Excel
Options6 = "Check"

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

HKEY_LOCAL_MACHINE\Software\Microsoft\
Office\8.0\New User Settings\
Excel\Microsoft Excel
Options6 = "{blank}"

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

HKEY_USERS\.Default\Software\
Microsoft\Office\8.0\
Excel\Microsoft Excel
Options6 = "Whoa"

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

HKEY_CURRENT_USER\Software\Microsoft\
Office\8.0\PowerPoint\
Options
MacroVirusProtection = "{blank}"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Office\8.0\New User Settings\
PowerPoint\Options
MacroVirusProtection = "{blank}"

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

HKEY_USERS\.Default\Software\
Microsoft\Office\8.0\
PowerPoint\Options
MacroVirusProtection = "{blank}"

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

NOTES:

It modifies the following files:

  • {MS Word Application path}\Normal.dot
  • {MS Powerpoint Application path}\Blank Presentation.pot

It disables the virus protection of MS PowerPoint and MS Excel. It also copies its codes to opened MS Excel and MS PowerPoint files.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.672.05

FIRST VSAPI PATTERN DATE:

28 Dec 2011

VSAPI OPR PATTERN File:

8.673.00

VSAPI OPR PATTERN Date:

29 Dec 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 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_CURRENT_USER\Software\Microsoft\Office\8.0\Excel\Microsoft Excel
    • From: Options6 = "Check"
      To: Options6 = "{User Defined}"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Office\8.0\New User Settings\Excel\Microsoft Excel
    • From: Options6 = "{blank}"
      To: Options6 = "{User Defined}"
  • In HKEY_USERS\.Default\Software\Microsoft\Office\8.0\Excel\Microsoft Excel
    • From: Options6 = "Whoa"
      To: Options6 = "{User Defined}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Office\8.0\PowerPoint\Options
    • From: MacroVirusProtection = "{blank}"
      To: MacroVirusProtection = "{User Defined}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\8.0\New User Settings\PowerPoint\Options
    • From: MacroVirusProtection = "{blank}"
      To: MacroVirusProtection = "{User Defined}"
  • In HKEY_USERS\.Default\Software\Microsoft\Office\8.0\PowerPoint\Options
    • From: MacroVirusProtection = "{blank}"
      To: MacroVirusProtection = "{User Defined}"

Step 3

Scan your computer with your Trend Micro product to delete files detected as O97M_TRISTATE.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.

Step 4

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.

  • {MS Word Application path}\Normal.dot
  • {MS Powerpoint Application path}\Blank Presentation.pot


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