Analysis by: Martin Xavier Co
ALIASES:

Ransom:Win32/Genasom (Microsoft); Ransom.AslaHora (Malwarebytes)

 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: Dropped by other malware, Downloaded from the Internet

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: 46,592 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 Jul 2017
Payload: 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.

Other Details

This Ransomware executes the following command to disable/stop/delete Windows components:

  • taskkill /f /im explorer.exe

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %User Profile%\Documents
  • %User Profile%\Documents\*
  • %User Profile%\Music
  • %User Profile%\Music\*
  • %User Profile%\Pictures
  • %User Profile%\Pictures\*
  • %User Profile%\Downloads
  • %User Profile%\Downloads\*
  • %Desktop%
  • %Desktop%\*
  • D:\*
  • E:\*
  • A:\*
  • Z:\*
  • X:\*

(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.. %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.)

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

  • desktop.ini

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

  • {original filename}.malki

NOTES:

This ransomware's initial lock screen is a black lock screen:

After encrypting files, it also displays the lock screen below:

Clicking the unlock button (without checking agreement) will display the following message box:

Clicking the unlock button (with the agreement box ticked) will display the following message box:

To unlock, enter MALKIMALKIMALKI and tick the agreement check box:

After unlocking, this ransomware decrypts previously modified/encrypted files, and then displays the following message box:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.530.07
FIRST VSAPI PATTERN DATE: 13 Jul 2017
VSAPI OPR PATTERN File: 13.531.00
VSAPI OPR PATTERN Date: 14 Jul 2017

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

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

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

Step 4

Restore encrypted files from backup.


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