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Threat Encyclopedia

W97M_CRIGENT.A

ANALYSIS BY

Alvin John Nieto


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:
INFORMATION EXPOSURE:

  • Threat Type:Backdoor

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Infects files


This malware may arrive as an infected Word or Excel document. It uses Windows PowerShell to carry out its malicious routines.

This backdoor 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:

DOC

Memory Resident:

Yes

Initial Samples Received Date:

20 Mar 2014

Payload:

Compromises system security, Downloads files

Arrival Details

This backdoor 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 backdoor creates the following folders:

  • %ApplicationData%\{GUID}

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{GUID} = "wscript.exe %ApplicationData%\{GUID}\{GUID}.vbs"

Backdoor Routine

This backdoor opens the following ports:

  • 8123 - Used for Web Proxy (Polipo)
  • 9050 - Used for traffic encryption (TOR)

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}jqj42hu.onion/get.php?s=setinfo&uid={GUID}
  • http://{BLOCKED}ormjqj42hu.onion/get.php?s=setup&uid={GUID}

It posts the following information to its command and control (C&C) server:

  • IP Address
  • Country code
  • Country name
  • Region code
  • Region name
  • City
  • Zipcode
  • Latitude
  • User account privilege
  • OS version
  • OS architecture
  • Domain
  • OS Language
  • Microsoft Office applications
  • Microsoft Office application versions

Download Routine

This backdoor connects to the following URL(s) to download its component file(s):

  • http://i.{BLOCKED}n.de/
  • http://gg.{BLOCKED}z.cc/

It saves the files it downloads using the following names:

  • %ApplicationData%\{GUID}\{GUID}.zip - contains 'tor.exe' and 'polipo.exe'
  • %ApplicationData%\{GUID}\tor.exe
  • %ApplicationData%\{GUID}\polipo.exe
  • %ApplicationData%\{GUID}\{GUID}.vbs - C&C generated file

Other Details

This backdoor connects to the following URL(s) to get the affected system's IP address:

  • http://freegeoip.net/json/

It drops the following file(s)/component(s):

  • %ApplicationData%\{GUID}\roaminglog - TOR initialization log

NOTES:
This backdoor retrieves the infection routine from the C&;C server to infect files with the following extension:

  • *.doc
  • *.docx
  • *.xls
  • *.xlsx

This backdoor saves a copy of each *.docx files to *.doc format and *.xlsx files to *.xls format under the same directory and deletes the original file.

This backdoor lowers the security setting of the following applications:

  • Microsoft Office Word
  • Microsoft Office Excel

SOLUTION

Minimum Scan Engine:

9.700

VSAPI OPR PATTERN File:

10.693.00

VSAPI OPR PATTERN Date:

29 Mar 2014

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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this 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\Windows\CurrentVersion\Run
    • {GUID} = "wscript.exe %ApplicationData%\{GUID}\{GUID}.vbs"

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %ApplicationData%\{GUID}\{GUID}.zip
  • %ApplicationData%\{GUID}\tor.exe
  • %ApplicationData%\{GUID}\polipo.exe
  • %ApplicationData%\{GUID}\roaminglog
  • %ApplicationData%\{GUID}\{GUID}.vbs

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as W97M_CRIGENT.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 6

Scan your computer with your Trend Micro product to delete files detected as W97M_CRIGENT.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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