Priya Nair — Digital Forensics Analyst
Key Takeaways
- The Maze ransomware employs advanced evasion techniques through double encryption and a unique attack vector.
- Initial access is often achieved via socially engineered phishing campaigns targeting enterprises.
- Common persistence mechanisms include scheduled tasks and Registry modifications that allow for recovery after reboots.
Executive Summary
This analysis details the capabilities and behavior of the Maze ransomware, a significant threat actor using sophisticated techniques for data exfiltration and encryption. The incident we investigated involved a series of infiltrations into a corporate network followed by the encryption of sensitive data. Maze’s technique of exfiltrating data prior to encryption enhances its leverage in extortion activities. During our investigation, we traced the attack chain from initial access to lateral movement, highlighting key actions and indicators of compromise (IOCs) encountered at every stage.
Initial Access
The attack began with a successful phishing campaign targeting employees of the victim organization. Our analysis revealed that the actor sent emails containing malicious attachments disguised as legitimate documents. These documents, when opened, executed a PowerShell script that downloaded the Maze payload from an external server. The use of the CVE-2017-0199 vulnerability allowed for the execution of arbitrary code, facilitating further exploitation. Following initial access, the malware dropped itself into the %APPDATA%\Roaming\Windows\System32\ directory with a random filename, ensuring stealth during further operations.
Execution & Persistence
Once the Maze implant was executed, it established persistence using a combination of scheduled tasks and registry modifications. We observed entries added to the Windows Task Scheduler to ensure re-execution upon system restarts, specifically targeting tasks named after system processes to evade detection. Additionally, the malware created registry keys under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\ to maintain persistence. The quick iteration through the system’s configuration enabled the actor to withstand reboots and remediation efforts from the IT security team.
Command and Control
The Maze ransomware employed robust command-and-control (C2) mechanisms to maintain communication with its operators. Our investigation highlighted the use of C2 URLs that featured randomized strings, making detection difficult. The implant frequently attempted to connect to these URLs using HTTP requests, which were observed in the traffic logs, demonstrating the actor’s meticulous planning to ensure continued access and control. The command channel allowed the operators to issue commands for data exfiltration and encryption at will, effectively facilitating the ransom negotiations that followed.
Lateral Movement & Discovery
Post-exploitation, the actor ventured into lateral movement to identify additional targets within the network. Utilizing WMIC and PSEXEC, we noted attempts to breach additional machines using stolen credentials harvested from the initial infected machine. The attacker exploited existing trust relationships via T1075 – Pass the Hash, allowing them to escalate privileges and move deeper into the environment. During this process, tools such as Mimikatz were deployed to gather user credentials, enhancing their ability to traverse the network undetected.
Impact & Objectives
The Maze ransomware’s primary objective was dual-faceted: data encryption and exfiltration. The actor’s approach not only encrypted data on the victim’s machines but also created local backups of data to fuel their extortion efforts underscoring the impact on business continuity. Additionally, the multitude of files encrypted was indicative of a more targeted approach, as they specifically selected files related to sensitive client data. This strategic manner of operation maximized pressure on the victim to pay the ransom to avoid public exposure of their proprietary data.
MITRE ATT&CK Mapping
- T1566 – Phishing: The actor utilized spear phishing emails as the initial attack vector.
- T1193 – Spear Phishing Attachment: Malicious documents were sent as email attachments to facilitate initial access.
- T1071.001 – Application Layer Protocol: Web Protocols: Command and control communications utilized HTTP/S protocols.
- T1210 – Exploitation of Remote Services: Leveraging the CVE-2017-0199 vulnerability to exploit Microsoft Office applications.
- T1035 – Service Execution: Utilized scheduled tasks for persistence.
Detection Opportunities
- Monitor email logs for indicators of phishing attempts, especially suspicious attachments.
- Implement detection rules for unusual registry modifications related to persistence mechanisms.
- Analyze outbound traffic for abnormal connections to known C2 domains or IP addresses.
Analyst Notes
This case emphasizes the need for organizations to enhance their cybersecurity posture by defending against phishing attempts and actively monitoring for signs of lateral movement and unauthorized C2 communications. Given the evolving tactics of Maze and similar actors, continuous threat intelligence gathering and swift incident response capabilities are paramount. Organizations should conduct regular training sessions for employees on identifying phishing attempts and maintain updated incident response protocols to minimize impact from such sophisticated ransomware operations.
Source: Original Report