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VBS_CRIGENT.LK
Malware type: Backdoor
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet

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: VBS
Memory resident: Yes
Initial samples received date: 07 Mar 2014
Payload: Connects to URLs/IPs, Compromises system security

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}

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=autorun&uid={GUID}

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}\roaming.zip - contains 'tor.exe' and 'polipo.exe'
  • %ApplicationData%\{GUID}\tor.exe
  • %ApplicationData%\{GUID}\polipo.exe

Other Details

This backdoor drops the following file(s)/component(s):

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

NOTES:

This backdoor requires the application Windows PowerShell to execute properly.

Solution


Minimum scan engine: 9.700
First VSAPI Pattern File: 10.648.05
First VSAPI Pattern Release Date: 07 Mar 2014
VSAPI OPR Pattern Version: 10.649.00
VSAPI OPR Pattern Release Date: 08 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

Search and delete these files

[ 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.
  • %ApplicationData%\{GUID}\roaming.zip
  • %ApplicationData%\{GUID}\tor.exe
  • %ApplicationData%\{GUID}\polipo.exe
  • %ApplicationData%\{GUID}\roaminglog

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as VBS_CRIGENT.LK. 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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Analysis By: Alvin John Nieto

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