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Ransom_MIMICRY.THIOGAH

October 22, 2018
 Analysis by: Robert Nicole Malagad
 ALIASES:

Trojan.Win32.Hesv.dlcf (Kaspersky)

 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

Infection Channel:

Spammed via email, Downloaded from the Internet, Dropped by other malware

This Ransomware arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

155,648 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Aug 2018

Payload:

Connects to URLs/IPs, Displays message/message boxes

Arrival Details

This Ransomware arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It 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 encrypts files with the following extensions:

  • .good

It does the following:

  • It drops a ransom note in every directory that the malware had successfully encrypted.
  • It needs to connect to the following server to proceed to its file encryption routine:
      {BLOCKED}.{BLOCKED}.17.172
  • After its encryption routine it will open the dropped ransom note text file "C:\HOW_TO_RECOVER_FILES.txt".
      mimicry.jpg
  • It will encrypt all files in all drives except the C drive.

It is capable of encrypting files in the affected system.

Ransomware Routine

This Ransomware drops the following file(s) as ransom note:

  • {File Directory}\HOW_TO_RECOVER_FILES.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.490.05

FIRST VSAPI PATTERN DATE:

07 Sep 2018

VSAPI OPR PATTERN File:

14.491.00

VSAPI OPR PATTERN Date:

08 Sep 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

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.  
  • {Encrpyted Directory}\HOW_TO_RECOVER_FILES.txt

Step 4

Restore encrypted files from backup.

Step 5

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