Analysis by: Jay Bradley Nebre
ALIASES:

Ransom:Win32/Gerber.A!MTB(Microsoft); a variant of Win32/Filecoder.Gerber.B trojan(NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • 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 encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size: 392,192 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Dec 2018
Payload: Displays graphics/image, Displays message/message boxes, Encrypts files, Sets desktop wallpaper to specific image, Hides files and processes

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 leaves text files that serve as ransom notes containing the following:

  • %Desktop%\Decrypt.TXT

Other System Modifications

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\GRBR~RANSOMWARE.BMP

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

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

Other Details

This Ransomware displays the following message boxes:


It does the following:

  • Hides files by modifying desktop.ini files

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, XP, and Server 2003, or C:\Users\{user name} on Windows Vista, 7, and 8.)

It avoids encrypting files found in the following folders:

  • %Windows%
  • %Program Files%

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

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

  • .!!{5 random characters}!!.MrAlex.gerber5

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.680.02
FIRST VSAPI PATTERN DATE: 10 Dec 2018
VSAPI OPR PATTERN File: 14.681.00
VSAPI OPR PATTERN Date: 11 Dec 2018

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

Restart in Safe Mode

[ Learn More ]

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\Control Panel\Desktop
    • Wallpaper data = %User Temp%\GRBR~RANSOMWARE.BM
  • In HKEY_CURRENT_USER\Control Panel\Desktop
    • TileWallpaper = 0

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 Temp%\GRBR~RANSOMWARE.BMP
  • %Desktop%\Decrypt.TXT

Step 6

Reset your Desktop properties

[ Learn More ]

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.GERBER.THABAOAH. 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 8

Restore encrypted files from backup.

Step 9

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.GERBER.THABAOAH. 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:


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