Threat Assessment: Matrix Ransomware

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Category: Unit 42

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A conceptual image designed to accompany the Unit 42 threat asessment of the Matrix ransomware family

This post is also available in: 日本語 (Japanese)

Executive Summary

Matrix is a ransomware family that was first identified publicly in December 2016. Over the years since its inception, it has primarily targeted small- to medium-sized organizations. As of 2019, it had been observed across geographic locations such as the U.S., Belgium, Taiwan, Singapore, Germany, Brazil, Chile, South Africa, Canada and the UK. While initially leveraging tactics such as spam email campaigns, propagation via Windows shortcuts and the RIG exploit kit for distribution, the primary attack vector for the Matrix ransomware family shifted in 2018 to brute forcing weak Remote Desktop Protocol (RDP) credentials. The shift to this attack methodology appears to be a recurring trend in similar targeted ransomware families such as Dharma, Ryuk and BitPaymer.

Matrix Ransomware Overview

This screenshot of a note produced by the Matrix ransomware family begins, "All your valuable data has been encrypted!" A key paragraph of interest reads, "We can prove that we can decrypt all your data. Please just send us 3-5 small encrypted files which are randomly stored on your server. We will decrypt these files and send them to you as proof. Please note that files for free test decryption should not contain valuable information." This paragraph describes a technique that appears relatively unique to Matrix.
Figure 1. Screenshot of Matrix ransom note

When executed, Matrix encrypts user files and network shares, as well as deleting volume shadow copies and disabling recovery options on the affected device. Like with many other ransomware variants, the ransom note delivered by Matrix demands payment in Bitcoin. Instead of spreading through an organization, past Matrix infections appear to have been more targeted in nature.

Matrix is unique in that instead of delivering a more conventional ransom note that demands a fixed ransom amount, the threat actors behind it ask victims to contact them directly and submit a small sample of about three to five files for decryption. This is done so the threat actors can determine a variable ransom based on factors such as the predicted value of the victim’s files or the current dollar value of Bitcoin.

As of 2020, Matrix ransomware has been seen appending the following file extensions on files:
.MTXLOCK, .CORE, .ANN, .FOX, .KOK8, .KOK08, .NEWRAR, .FASTBOB, .FASTB, .EMAN, .THDA, .RAD, .EMAN50, .GMPF, .ATOM, .NOBAD, .TRU8, .FASTA, .JNSS, .FBK, .ITLOCK, .SPCT, .PRCP, .CHRB, .AL8G, .DEUS, .FG69, .JB88, .J91D, .S996, .[barboza40@yahoo.com], .[Linersmik@naver.com][Jinnyg@tutanota.com], .[poluz@tutanota.com], .[Yourencrypt@tutanota.com], .[Files4463@tuta.io], .[RestorFile@tutanota.com], .[RestoreFile@qq.com], .[oken@tutanota.com], .[Vfemacry@mail-on.us], .[d3336666@tutanota.com], and .[Bitmine8@tutanota.com]

In addition, Matrix has other variants, including one dubbed “Fox Ransomware,” which adds the “.FOX” extension to encrypted files.

More information on prominent ransomware families can be found in the 2021 Unit 42 Ransomware Threat Report.

Courses of Action

This section documents relevant tactics, techniques and procedures (TTPs) used with Matrix and maps them directly to Palo Alto Networks product(s) and service(s). It also further instructs customers on how to ensure their devices are configured correctly.

Product / Service Course of Action

Initial Access, Persistence, Lateral Movement

The below courses of action mitigate the following techniques:
Spearphishing Attachment [T1566.001], Valid Accounts [T1078], Replication Through Removable Media [T1091], Remote Desktop Protocol [T1021.001]

NGFW Set up File Blocking
Ensure that security policies restrict User-ID Agent traffic from crossing into untrusted zones
Ensure application security policies exist when allowing traffic from an untrusted zone to a more trusted zone
Ensure 'Service setting of ANY' in a security policy allowing traffic does not exist
Ensure 'Security Policy' denying any/all traffic to/from IP addresses on Trusted Threat Intelligence Sources Exists
Ensure that User-ID is only enabled for internal trusted interfaces
Ensure that 'Include/Exclude Networks' is used if User-ID is enabled
Ensure that the User-ID Agent has minimal permissions if User-ID is enabled
Ensure that the User-ID service account does not have interactive logon rights
Ensure remote access capabilities for the User-ID service account are forbidden
Threat Prevention Ensure that antivirus profiles are set to block on all decoders except 'imap' and 'pop3'
Ensure a secure antivirus profile is applied to all relevant security policies
Ensure that all zones have Zone Protection Profiles with all Reconnaissance Protection settings enabled, tuned and set to appropriate actions
WildFire Ensure that WildFire file size upload limits are maximized
Ensure forwarding is enabled for all applications and file types in WildFire file blocking profiles
Ensure a WildFire Analysis profile is enabled for all security policies
Ensure forwarding of decrypted content to WildFire is enabled
Ensure all WildFire session information settings are enabled
Ensure alerts are enabled for malicious files detected by WildFire
Ensure 'WildFire Update Schedule' is set to download and install updates every minute
Cortex XDR Configure Host Firewall Profile
Configure Malware Security Profile
Enable Device Control
Cortex XSOAR Deploy XSOAR Playbook - Block Account Generic
Deploy XSOAR Playbook - Access Investigation Playbook
Deploy XSOAR Playbook - Impossible Traveler
Deploy XSOAR Playbook - Phishing Investigation - Generic V2
Deploy XSOAR Playbook - Endpoint Malware Investigation
Credential Access
The below courses of action mitigate the following techniques:
Brute Force [T1110]
NGFW Customize the Action and Trigger Conditions for a Brute Force Signature
Cortex XSOAR Deploy XSOAR Playbook - Brute Force Investigation Playbook
Execution, Defense Evasion, Persistence, Privilege Escalation, Impact
The below courses of action mitigate the following techniques:
Windows Command Shell [T1059.003], Match Legitimate Name or Location [T1036.005], Services File Permissions Weakness [T1574.010], Disable or Modify Tools [T1562.001], Service Stop [T1489], Modify Registry [T1112], Data Encrypted for Impact [T1486], Inhibit System Recovery [T1490]
Cortex XDR Enable Anti-Exploit Protection
Enable Anti-Malware Protection
Configure Restrictions Security Profile
Configure Behavioral Threat Protection under the Malware Security Profile
Cortex XSOAR Deploy XSOAR Playbook - Ransomware Manual for incident response.
Deploy XSOAR Playbook - Palo Alto Networks Endpoint Malware Investigation

Table 1. Courses of Action for Matrix ransomware.
†These capabilities are part of the NGFW security subscriptions service.

Conclusion

While targeted ransomware attacks are not new, Matrix is a prime example of how threat actors can enter into the pool of existing ransomware and cash out quickly by targeting low-hanging fruit. The ransom negotiation tactics used by the Matrix threat actors further amplifyies the dangerous impact that such an attack can have on its victims, especially given the volatile state of cryptocurrency value today. Furthermore, this malware family’s shift in tactics to RDP exploitation, following a similar shift seen in other ransomware groups, serves to emphasize the need for businesses to stay vigilant on current ransomware trends.

Palo Alto Networks detects and prevents Matrix in the following ways:

  • WildFire: All known samples are identified as malware.
  • Cortex XDR with:
    • Iindicators for Matrix.
    • Anti-Ransomware Module to detect Matrix encryption behaviors.
    • Local Analysis detection to detect Matrix binaries.
  • Next-Generation Firewalls: DNS Signatures detect the known command and control (C2) domains, which are also categorized as malware in URL Filtering.
  • AutoFocus: Tracking related activity using the MatrixRansomware tag.

Additionally, Indicators of Compromise (IoCs) associated with Matrix are available on GitHub here, and have been published to the Unit 42 TAXII feed.

Additional Resources