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RANSOM_GOMME.B

September 28, 2017
 ALIASES:

Trojan.MalPack (Malwarebytes); Ransom:MSIL/Gommyrypt.A (Microsoft); Mal/Gommran-A (Sophos)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Ransomware connects to certain websites to send and receive information.

It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

14,336 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

01 Jun 2017

Payload:

Encrypts files

Installation

This Ransomware drops the following files:

  • %User Profile%\keygenerated -> used as marker that encryption was done

(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 and 7.)

It terminates itself if it finds the following processes in the affected system's memory:

  • Wireshark

Other Details

This Ransomware connects to the following website to send and receive information:

  • http://{BLOCKED}tti.pro/gommeransom/btc.txt
  • http://{BLOCKED}ti.pro/gommeransom/ip.php
  • http://{BLOCKED}ti.pro/gommeransom/cheggki.php?key={Decryption Key}
  • http://{BLOCKED}tti.pro/gommeransom/1231.php?1={Personal Key}

It does the following:

  • It bypasses all its functions if the user name is "Admoooon"

It checks if the following virtual machine or sandbox related module(s) is loaded in the affected system:

  • SbieCtrl

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %Desktop%
  • %User Profile%\Documents
  • %User Profile%\Downloads

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %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 and 7.)

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

  • Bild
  • Picture
  • .ini
  • gommemode
  • {Executing Assembly}
  • {Malware Name}

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

  • .gommemode

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.444.04

FIRST VSAPI PATTERN DATE:

01 Jun 2017

VSAPI OPR PATTERN File:

13.445.00

VSAPI OPR PATTERN Date:

02 Jun 2017

Step 1

Scan your computer with your Trend Micro product to delete files detected as RANSOM_GOMME.B. 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 2

Search and delete this file

[ 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%\keygenerated

Step 3

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 4

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

Step 5

Restore encrypted files from backup.


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