Analysis by: Bren Matthew Ebriega
ALIASES:

Ransom:Win32/Crystalcrypt.A (MICROSOFT); HEUR:Trojan-Ransom.MSIL.Agent.gen (KASPERSKY)

 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 found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 216,064 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 09 Oct 2019
Payload: Connects to URLs/IPs, Encrypts files, Displays graphics/image, Collects system information

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.

Information Theft

This Ransomware gathers the following data:

  • Username
  • OS Version
  • Hardware ID

Stolen Information

This Ransomware sends the gathered information via HTTP POST to the following URL:

  • http://arizonacode.{BLOCKED}d.net/rnsm/add.php?type=add&data=InfinityCrypt|{Username}|{Encryption Key}|{OS Version}|{Hardware ID}|{Number of Encrypted Files}

Other Details

This Ransomware does the following:

  • Due to an error encountered when it is sending the stolen data, it will not be able to perform its ransom note dropping routine.
  • It shows the following window after encryption if its information theft routine is successful:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • {Drive Letter except C}:\
  • %Public%\Music
  • %Public%\Pictures
  • %Public%\Videos
  • %Public%\Documents
  • %User Profile%\Music
  • %User Profile%\Pictures
  • %User Profile%\Videos
  • %User Profile%\Documents
  • %User Profile%\Downloads
  • %User Profile%\OneDrive
  • %Common Programs%
  • %Programs%
  • %Program Files%\Common Files
  • %Program Files%

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Common Programs% is the folder that contains common program groups for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs on Windows Vista, 7, and 8.. %Programs% is the folder that contains the user’s program groups, which is usually C:\Windows\Start Menu\Programs or C:\Documents and Settings\{User name}\Start Menu\Programs on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs on Windows Vista, 7, and 8.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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

  • .lnk
  • desktop.ini

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

  • .{Hardware ID}

It drops the following file(s) as ransom note:

  • %Desktop%\InfinityLock_Recover_Instructions.txt
  • %Desktop%\InfinityLock_UniqeID.txt
  • %Desktop%\InfinityLock_Recover_Instructions.png

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.518.06
FIRST VSAPI PATTERN DATE: 04 Feb 2021
VSAPI OPR PATTERN File: 16.519.00
VSAPI OPR PATTERN Date: 05 Feb 2021

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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.MSIL.INFINITYLOCK.B

[ 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.  
  • %Desktop%\InfinityLock_Recover_Instructions.txt
  • %Desktop%\InfinityLock_UniqeID.txt
  • %Desktop%\InfinityLock_Recover_Instructions.png

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.MSIL.INFINITYLOCK.B. 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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