Analysis by: Augusto II Remillano
ALIASES:

Ransom.CryptXXX (Norton), Gen:Heur.Ransom.HiddenTears.1 (BitDefender)

 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

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: 17,920 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 31 May 2018
Payload: Drops files, 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.

Installation

This Ransomware drops the following files:

  • %User Profile%\master_pri_key.info - RSA private key
  • %User Profile%\master_public_key.info - RSA public key

(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.)

Other Details

This Ransomware does the following:

  • Opens a console displaying the following text:

    YOUR FILES ARE ENCRYPTED YOUR FINGERPRINT: {Hashed BIOS information of affected machine}

    SEND 0.01 BTC to address: {BLOCKED}

    SEND TRANSACTIONID (TXID) AND FINGERPRINT to {BLOCKED}tmefinger@gmail.com

    YOU RECEIVE DECRYPTOR INBOX
  • Checks the first 8 bytes of a file for its signature (0x3737451845184518) to determine whether it has already encrypted the said file.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .JPG
  • .GIF
  • .PDF
  • .PNG
  • .NEF
  • .ZIP
  • .RAR
  • .TAR
  • .GZ
  • .CS
  • .VB
  • .JAVA
  • .CLASS
  • .JS
  • .VBS
  • .CSC
  • .JSON
  • .TXT
  • .C
  • .CPP
  • .H
  • .CONFIG
  • .PY
  • .R
  • .XAML
  • .JSP
  • .PHP
  • .DOC
  • .DOCX
  • .XLS
  • .XLSX
  • .PPT
  • .PPTX
  • .MP3
  • .MP4
  • .AVI
  • .MPEG
  • .PST
  • .MSG
  • .EML
  • .DBX
  • .MBX
  • .WAB

It encrypts files found in the following folders:

  • C:\Users

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.286.02
FIRST VSAPI PATTERN DATE: 31 May 2018
VSAPI OPR PATTERN File: 14.287.00
VSAPI OPR PATTERN Date: 01 Jun 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

Identify and terminate files detected as RANSOM_LILFINGER.THECAAH

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

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.
  • %User Profile%\master_pri_key.info
  • %User Profile%\master_public_key.info

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_LILFINGER.THECAAH. 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 6

Restore encrypted files from backup.


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