Analysis by: Patrick Noel Collado
ALIASES:

WinGo/Filecoder.H trojan (Nod32), Trojan-Ransom.FileCrypter (Ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes then deletes itself afterward.

It encrypts files found in specific folders. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size: 3,615,744 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Mar 2021
Payload: Displays message/message boxes, Displays graphics/image, Encrypts files

Arrival Details

This Ransomware 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 Ransomware drops the following files:

  • %User Profile%\BAD_GOPHER.txt
  • %Desktop%\BAD_GOPHER.txt

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following copies of itself into the affected system:

  • %Desktop&\Restore Your Files.exe

It adds the following processes:

  • wbadmin "delete catalog - quiet"
  • bcdedit "/ set{ default } recoveryenabled no"
  • bcdedit "/ set{ default } bootstatuspolicy ignoreallfailures"
  • wmic "shadowcopy delete"
  • vssadmin "delete shadows /All /Quiet"

It executes then deletes itself afterward.

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Profile%\BAD_GOPHER.jpg

It sets the system's desktop wallpaper to the following image:

  • %User Profile%\BAD_GOPHER.jpg

Other Details

This Ransomware does the following:

  • Avoids encrypting files larger than 2gb.
  • Plays an audio warning that your files have been encrypted by badgopher ransomware.
  • Will not continue with its malicious routine if %User Profile%\BAD_GOPHER.txt is found and will show this instead:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %User Profile%

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It avoids encrypting files with the following strings in their file name:

  • bad_gopher
  • ntuser
  • restore your files.exe

It appends the following extension to the file name of the encrypted files:

  • .gopher

It avoids encrypting files with the following file extensions:

  • .pem
  • .gopher

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.586.04
FIRST VSAPI PATTERN DATE: 10 Mar 2021
VSAPI OPR PATTERN File: 16.587.00
VSAPI OPR PATTERN Date: 11 Mar 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Identify and terminate files detected as Ransom.Win32.BADGOPHER.THCAOBA

[ 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

Reset your Desktop properties

[ Learn More ]

Step 5

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.  %User Profile%\BAD_GOPHER.jpg 

%User Profile%\BAD_GOPHER.txt 

%Desktop%\BAD_GOPHER.txt 

%Desktop&\Restore Your Files.exe 

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.BADGOPHER.THCAOBA. 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 the following Trend Micro Support pages for more information:

Step 7

Restore encrypted files from backup.


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