Denuvo’s Demise: A Postmortem of Company of Heroes 3

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Company of Heroes 3: Denuvo’s Demise and the Path to Unprotected Code

This analysis examines the security implications surrounding the game Company of Heroes 3 (CoH3), focusing on its initial release with Denuvo anti-tamper technology, subsequent vulnerabilities, and eventual removal of the DRM. The discussion highlights the technical aspects of software protection and the vulnerabilities that can lead to its bypass. The target audience is security professionals, red teamers, and reverse engineers.

Vulnerability Summary: Denuvo and Licensing Failures

• CVSS: Not applicable (technical failures, not exploitable vulnerabilities in a traditional sense)
• Affected Versions: Initial releases of CoH3 containing Denuvo.
• Attack Vector: Exploitation of DRM licensing issues, leading to game bypass.

Technical Analysis: Denuvo’s Implementation and Failure

Company of Heroes 3, released on February 23, 2023, incorporated Denuvo anti-tamper technology and Steam DRM (T1609). The primary goal of Denuvo is to prevent unauthorized distribution and modification of the game executable. The implementation, however, introduced several points of failure, ultimately leading to its bypass and eventual removal.

The core issue revolved around the reliance on Denuvo’s licensing mechanism. The game required a valid license to launch, which was periodically checked in the background. Failures in this process, caused by expired licenses or improper updates, resulted in the inability to start the game.

Specific Failure Points:

• License Expiration: The most critical failure occurred when Denuvo licenses were not renewed, causing the game to fail to authenticate. This prevented legitimate users from playing the game.
• Update Failures: Issues during license updates caused launch problems, manifested as black screens or other errors, as described in the source text. (T1059.003 – Command and Scripting Interpreter: Windows Command Shell)
• External Dependencies: The game’s dependency on the Havok physics engine also presented a vulnerability point. A license issue with Havok prevented game launch in April 2024.

Proof of Concept: The NoDenuvoBuild

The “NoDenuvoBuild” release represents a successful bypass of the Denuvo protection. The key to the bypass was the accidental release of a version of the game without the Denuvo protection. This resulted in an easily accessible, unprotected executable. Reverse engineering tools could be used to analyze the differences between protected and unprotected executables.

The Edwynkir group likely discovered the absence of the Denuvo string in the executable. It is reasonable to assume they performed a detailed comparison between legitimate and problematic versions, identified the missing Denuvo components, and subsequently created a “clean” executable that bypassed the licensing checks (T1574.002 – Hijack Execution Flow: DLL Side-Loading). Although no exploit code is available for this accidental release, a reverse engineering analysis and file comparison of the executable would be the starting point.

Steps for analysis include:

1. Obtain legitimate and “NoDenuvo” versions of the game.
2. Use a disassembler (e.g., Ghidra, IDA Pro) to analyze the executables.
3. Identify function calls to Denuvo libraries and licensing verification routines.
4. Compare the code paths and identify the absence of key Denuvo checks.

Detection Opportunities: Behavioral Indicators

Security teams can monitor for several indicators to detect attempts to bypass DRM or unauthorized modifications of game executables:

• File Integrity Monitoring: Monitor file hashes of game executables. Any deviation from known good hashes should be investigated. (T1564.001 – Hide Artifacts: Hidden Files and Directories)
• Network Traffic Analysis: Unusual network connections from game executables can be investigated. (T1041 – Exfiltration Over C2 Channel) The absence of expected Denuvo authentication traffic could signal tampering.
• Process Behavior Monitoring: Monitor for suspicious processes. (T1059.003 – Command and Scripting Interpreter: Windows Command Shell) Tools like Sysmon can be used to track process creation, file access, and network activity.
• User Activity Monitoring: Unusual user behavior could be a sign of a compromised account. (T1078 – Valid Accounts)

Impact Assessment

The Denuvo failures and the subsequent “NoDenuvoBuild” represent a significant impact on the game’s security. The vulnerabilities allowed unauthorized users to bypass the game’s protection mechanisms. The incident illustrates the risk that can come from relying on third-party security solutions (supply chain compromise). While not a traditional exploit, the failure to maintain valid licenses and the accidental release of an unprotected version allowed for unrestricted access, highlighting the fragility of DRM and the value of robust security practices within software development and distribution.

The eventual removal of Denuvo in a later patch indicates that the developers recognized the costs and potential performance impact of the DRM, especially given the ease with which it was circumvented. (T1484.001 – Domain Policy Modification: Group Policy) This case serves as a reminder to conduct thorough software security reviews to mitigate risks during release and throughout the product’s life cycle.

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