Defending Against FIN8: Validate Your Ransomware Defenses with Targeted Attack Scenarios
- Markus Vervier
- Sep 3
- 6 min read
Known for their targeted ransomware campaigns and advanced persistence techniques, FIN8 has caused significant damage across multiple industries since 2016. With ransomware attacks costing organizations an average of $4.62 million per incident in 2023.
Validating your defenses against groups like FIN8 isn't just prudent, it's essential.
Understanding the FIN8 Threat Landscape
FIN8, tracked by MITRE as G0061, has evolved from a group focused on POS malware to a sophisticated ransomware operator. Their recent campaigns have deployed variants including Ragnar Locker, White Rabbit, and attempted deployments of Noberus ransomware. What makes FIN8 particularly dangerous is their methodical and patient approach: they don't just encrypt right away and run - over a longer period they establish persistence, move laterally, and ensure maximum impact before triggering their ransomware payload. This makes it hard to detect them compared to more aggressive actors.
The group's tactics, techniques, and procedures (TTPs) span across 11 of the 14 MITRE ATT&CK tactics, demonstrating a versatile attack methodology that challenges even mature security programs. You can explore their full TTP matrix through the MITRE ATT&CK Navigator, which visualizes the breadth of their operational capabilities. This complexity is precisely why point-in-time penetration tests fall short, also due to the time boxed nature of such activities—you need continuous validation against the full attack chain.
The Nemesis Approach: Threat-Informed Scenarios for Real-World Validation
Nemesis Breach and Attack Simulation (BAS) platform takes a methodical approach to defending against sophisticated threat actors like FIN8. By analyzing FIN8's known TTPs from the MITRE ATT&CK framework, we've created three comprehensive attack scenarios that mirror their real-world operations, but broken down into the individual steps and phases:
These scenarios aren't arbitrary groupings—they represent the logical progression of a FIN8 attack:
Initial Stages - How FIN8 establishes their foothold
Discovery, Lateral Movement and Persistence - How they spread through your network
Privilege Escalation, Credential Dumping, and Cleanup - How they deepen access and cover their tracks
Defenders can tackle each of these areas one by one or in progression and avoid being overwhelmed! Let's examine each scenario and understand how continuous validation can expose gaps in your defenses.
Scenario 1: Initial Stages - The Opening Gambit
The first scenario focuses on FIN8's initial compromise techniques, containing 10 atomic tests that validate your defenses against their entry methods:
Technical Breakdown:
Execution & Persistence Arsenal:
PowerShell Invocations (T1059.001): FIN8 heavily leverages PowerShell for initial payload execution, which is crucial for attackers to get a foothold and evade detections. Our atomic tests validate whether your EDR solution can detect and prevent suspicious PowerShell activities, including:
Encoded command execution for ofuscation
Bypassing locked down execution policies using -ExecutionPolicy Bypass
Known malicious cmdlet usage patterns
Windows Command Shell Exploitation (T1059.003): The scenario tests your ability to detect suspicious cmd.exe usage, particularly when spawned from unusual parent processes or containing encoded payloads. After the initial compromise attackers need to perform such activities to advance to their goals.
WMI Event Subscription (T1546.003): FIN8 establishes persistence through WMI, a technique that often flies under the radar. Our atomic validates whether your security controls can:
Detect WMI event filter creation
Block unauthorized WMI persistence mechanisms
Alert on suspicious WMI query patterns
Unfortunately attackers will not stay on the local system, therfore we also simulate data staging and exfiltration chains used to steal sensitive information:
File Discovery and Metadata Collection (T1074.001): Tests simulate FIN8's reconnaissance behavior, searching for valuable files across network shares and local systems.
Encrypted Channels via GPG (T1486): Before deploying ransomware, FIN8 often tests encryption capabilities. This atomic validates whether your DLP solutions can detect mass file encryption attempts.
Alternative Protocol Exfiltration (T1048.002/T1048.003): The scenario includes tests for data exfiltration over FTP, HTTPS, and FTPS—protocols FIN8 uses to blend malicious traffic with legitimate business communications.
Business Impact:
By continuously running these initial stage validations, organizations can:
Reduce mean time to detection (MTTD) for initial compromise from days to minutes
Validate security tool efficacy against real FIN8 techniques
Identify configuration gaps in PowerShell logging and script block analysis
Ensure data loss prevention controls can detect staging activities before exfiltration occurs
Scenario 2: Discovery, Lateral Movement, and Persistence - The Network Takeover
Once FIN8 gains initial access, they don't rush to deploy ransomware. Instead, they methodically map the environment and spread their influence. This scenario, containing 9 atomic tests, validates your ability to detect and prevent this reconnaissance phase:
Technical Breakdown:
Comprehensive Discovery Operations:
System Information Discovery (T1082): Tests validate detection of system profiling activities using native Windows utilities
Driver Enumeration via DriverQuery (T1082): FIN8 profiles systems to identify security software—can your SIEM correlate these reconnaissance patterns?
WinPwn PowerSQL Discovery (T1518): Advanced SQL server discovery techniques that often bypass traditional network scanning detection
Security Software Discovery (T1518.001): Direct registry queries to identify installed security products
Persistence Mechanisms:
WMI for Reconnaissance (T1047): Beyond execution, FIN8 uses WMI for stealthy system enumeration
Firewall Rule Enumeration (T1016): Identifying firewall exceptions that might facilitate C2 communications or lateral movement
The Lateral Movement Chess Game:
FIN8's lateral movement is very targeted. They identify high-value systems through Active Directory reconnaissance, then move methodically using legitimate administrative tools. Therfore detection is crucial! If you suspect malicious activity the key thing is to have visiblity and being able to audit all actions, also seemingly legitimate ones.
Our atomics trigger such events and allow you to engineer your detections so that you can detect:
Abnormal WMI usage patterns across multiple hosts
Unusual authentication patterns indicating credential reuse
Network scanning from compromised internal hosts
Business Impact:
Organizations that fail to detect lateral movement face:
Extended dwell time (FIN8's average is 11 days before ransomware deployment)
Increased blast radius when ransomware eventually deploys
Higher likelihood of complete domain compromise
Exponentially higher recovery costs and downtime
Continuous validation ensures your security stack can break the kill chain during this critical phase.
Scenario 3: Privilege Escalation, Credential Dumping, and Cleanup - The Final Act
The most comprehensive scenario contains 20 atomic tests focusing on FIN8's endgame tactics:
Technical Breakdown:
Attackers exfiltrate authentication credentials through well known and customized tools. In the cat and mouse game of detection and evasion, it’s crucial to have the capability to detect their latest Credential Harvesting Arsenal:
Multiple Mimikatz Variants (T1003.001): Tests include both PowerShell-based and compiled versions, validating whether your endpoint protection can detect:
In-memory credential dumping
LSASS process access patterns
Known Mimikatz signatures and behaviors
Advanced LSASS Dumping Techniques: Beyond basic Mimikatz, the scenario tests:
Comsvcs.dll abuse for LSASS dumps
ProcDump legitimate tool abuse
Direct memory access patterns
For FIN8 gaining higher privileges is crucial to reach their goals, therefore preventing such vectors and detecting it is a must. To help you Nemesis provides Privilege Escalation Validation:
Tests simulate exploitation of known vulnerabilities FIN8 has used
Validates detection of suspicious token manipulation
Checks for unauthorized privilege assignments
FIN8 being patient and stealthy tries to hide from your view as much as possible, to counter this engineer your mitigations and detections against Anti-Forensics and Cleanup:
Event Log Clearing (T1070.001): Can your SIEM detect when logs are wiped?
File Deletion Patterns: Tests for mass deletion of artifacts
Registry Key Removal: Validates detection of persistence mechanism cleanup
The Remote Access Dimension:
FIN8 maintains multiple backdoors, and this scenario specifically tests:
RDP enablement and configuration changes
Creation of new local administrator accounts
SMB/Windows Admin Share abuse for lateral movement
Domain controller targeting patterns
Business Impact:
This phase represents your last chance to prevent catastrophic ransomware deployment. Organizations need to know:
Can credential dumping be detected before attackers exfiltrate your entire password database?
Will privilege escalation attempts trigger immediate incident response?
Are cleanup activities generating alerts that indicate an imminent ransomware deployment?
Continuous Validation: Your Shield Against FIN8
The strength of Nemesis lies not just in these meticulously crafted scenarios, but in the ability to run them continuously and strengthen your defense in depth. FIN8 doesn't attack once - they evolve their techniques and harvest the targets they can breach. Stay outside of that pool based on defensive improvements and equally dynamic validation.
Key Advantages of the Nemesis Approach:
MITRE-Aligned Testing: Every atomic maps directly to techniques documented in the MITRE ATT&CK framework, ensuring comprehensive coverage of known FIN8 behaviors.
Safe Production Testing: Nemesis atomics are designed to validate without disruption, allowing daily or weekly validation cycles.
Granular Control Validation: Each atomic test provides specific feedback on which security controls succeeded or failed, enabling targeted improvements.
Sequential Attack Simulation: The scenarios can run in sequence, mimicking FIN8's actual attack progression and validating your defense-in-depth strategy.
Nemesis transforms the question from "Could FIN8 compromise us?" to "Here's exactly where FIN8 would fail, and here's where we need improvement." This shift from uncertainty to evidence-based security is the difference between hoping your defenses work and knowing they will.
Next Steps:
Deploy Nemesis Agents across representative systems in your environment
Run the FIN8 scenarios to establish your security baseline
Analyze results to identify control gaps and misconfigurations
Implement improvements based on specific atomic test failures
Continuously validate to ensure defenses remain effective as your environment evolves
In the high-stakes game of ransomware defense, you can't afford to guess. With Nemesis, you don't have to. Validate, improve, and stay ahead of groups like FIN8.
Ready to validate your defenses against FIN8 and other advanced ransomware operators? Contact us to see Nemesis in action or start your trial today.
