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RANSOM_SYSTEM.THAAOEAH

December 18, 2018
 Analysis by: Henry Alarcon Jr.
 ALIASES:

Gen:Variant.MSILPerseus.170079 (BitDefender), MSIL/Filecoder.PP!tr.ransom (Fortinet), Trojan:Win32/Tiggre!rfn (Microsoft)

 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 with specific file extensions. It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

75,264 bytes

File Type:

EXE

Memory Resident:

No

Payload:

Encrypts files, Displays graphics/image, Displays windows

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.

Autostart Technique

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

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
System = {malware path}\{malware file}.exe

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • taskmgr
  • regedit
  • ProcessHacker

Other Details

This Ransomware does the following:

  • After encrypting files it display the following:

    • If Payer clicked:


    • If Decrypter clicked:


  • If you input letters "mdp" and clicked the button it will start to decrypt all the encrypted files and created autorun registries.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .txt

It encrypts files found in the following folders:

  • D:\rsw

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

  • .encrypt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.608.03

FIRST VSAPI PATTERN DATE:

05 Nov 2018

VSAPI OPR PATTERN File:

14.600.00

VSAPI OPR PATTERN Date:

06 Nov 2018

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

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\Software\Microsoft\Windows\CurrentVersion\Run
    • System = "{Malware path}\{malware file}.exe"

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_SYSTEM.THAAOEAH. 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 5

Restore encrypted files from backup.


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