Analysis by: Mark Joseph Manahan
ALIASES:

Mal/Behav-116 (Webroot)

 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: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This backdoor may be dropped by other malware.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It creates an event.

  TECHNICAL DETAILS

File Size: 42,095 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Dec 2012
Payload: Compromises system security

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_ARTIEF.RTN

Installation

This backdoor drops the following files:

  • %User Temp%\OsInfo.dat
  • {Malware Path}\netchk.vbs

(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 the following copies of itself into the affected system:

  • %User Temp%\net1.exe

(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.)

Autostart Technique

This backdoor drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • NetShare.lnk

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonZoneCrossing = "1"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download and execute arbitrary files
  • Get Network Information
  • Get Username/Computername
  • Get OS Information
  • Get Running Process
  • Get Intalled Applications
  • Perform shell command

It connects to the following websites to send and receive information:

  • http://{BLOCKED}ws-google.net:443
  • http://{BLOCKED}ws-google.net:80

Other Details

This backdoor creates the following event(s):

  • QZHKVGYS

NOTES:

It queries the default web browser by accessing the following registry entry:

HKEY_CLASSES_ROOT\http\shell\open\command

It then launches a hidden web browser process (e.g. iexplore.exe). The malware then injects its code containing its backdoor routines.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.576.04
FIRST VSAPI PATTERN DATE: 07 Dec 2012
VSAPI OPR PATTERN File: 9.577.00

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

Remove malware/grayware files that dropped/downloaded BKDR_GAMFRIC.A

     TROJ_ARTIEF.RTN

Step 3

Identify and terminate files detected as BKDR_GAMFRIC.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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\Internet Settings
    • WarnonZoneCrossing = "1"

Step 5

Search and delete this file

[ 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%\OsInfo.dat
  • {Malware Path}\netchk.vbs
  • %User Startup%\NetShare.lnk

Step 6

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