RANSOM_MFESTUS.A

December 28, 2016
 Analysis by: Marvelous Pelin
 ALIASES:

Ransom.FileCryptor(Malwarebytes)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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

  TECHNICAL DETAILS

File Size:

37,888 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Dec 2016

Payload:

Encrypts files, Displays graphics/image

Arrival Details

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

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
DO NOT OPEN THE FUCKING RANSOMWARE = {path of the executed copy}

Other Details

This Trojan renames encrypted files using the following names:

  • {original filename and extension}.fucked

It does the following:

  • This ransomware requires a key in order to decrypt the encrypted files. The key is "Cq01toI7EkOa".
  • It displays the following after successfully entering the required key:

NOTES:

This ransomware displays the following after execution:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.940.03

FIRST VSAPI PATTERN DATE:

22 Dec 2016

VSAPI OPR PATTERN File:

12.941.00

VSAPI OPR PATTERN Date:

23 Dec 2016

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

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • DO NOT OPEN THE FUCKING RANSOMWARE = {path of the executed copy}

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_MFESTUS.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 6

Restore encrypted files from backup.


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