Cyber Attack Unveiled: Malicious NuGet Packages Embed Delayed Sabotage

Researchers at Socket have uncovered a sophisticated supply-chain attack involving nine malicious NuGet packages. These packages, downloaded 9,488 times prior to the discovery, stealthily embed time-delayed sabotage code within otherwise legitimate .NET libraries. This method allows the attackers to execute harmful operations under the guise of trusted software, significantly elevating risks for organizations that rely on these packages.

Mechanism of Attack

The malicious packages were released under the alias shanhai666 between 2023 and 2024. Each package masquerades as a functional library while incorporating approximately 20 lines of harmful code. This code exploits C# extension methods, such as .Exec() and .BeginTran(), to ensure that every database command or PLC (Programmable Logic Controller) operation inadvertently triggers the sabotage routines.

These routines feature hardcoded or encrypted activation dates, allowing the payload to calculate a random number and execute a command to terminate the application abruptly. Some of the triggers are set to activate in 2027 and 2028, extending the attackers’ ability to compromise systems before detection occurs.

One of the most concerning packages identified, Sharp7Extend, employs two distinct sabotage mechanisms. The first involves an immediate process termination on every PLC operation, remaining active until June 6, 2028. The second mechanism introduces a delayed write-failure feature, which returns erroneous results for up to 80% of write attempts after a 30 to 90-minute window. This could lead to significant operational failures, such as actuator non-responses and undetected production drifts, mimicking hardware malfunctions rather than a deliberate attack.

Challenges in Detection

The intricacies of these packages contribute to their evasion of detection. The majority of the code remains legitimate, enabling it to pass functional testing and code reviews seamlessly. Typosquatting tactics, such as using names similar to Sharp7, increase the likelihood of accidental installations within operational technology environments.

Furthermore, the inclusion of trusted libraries masks potential red flags during testing, while the probabilistic nature of the activation disguises systematic interruptions as random failures. Long delays between installation and activation can obscure forensic timelines, complicating the identification of impacts once they occur. The attacker has also varied author metadata and forged signature artifacts to hinder automated detection methods.

Strengthening Supply Chain Resilience

Addressing the risks posed by this NuGet campaign necessitates both immediate and ongoing measures to enhance supply chain resilience. Organizations are advised to conduct thorough audits of their dependencies, removing or replacing any of the nine malicious packages without delay.

Implementing robust dependency hygiene is crucial. This includes requiring verified publisher metadata, prohibiting typosquatted names, and restricting package sources to approved registries. Additionally, integrating Software Bill of Materials (SBOM) checks and static analysis into continuous integration and deployment (CI/CD) pipelines can help flag suspicious time-based logic and unusual use of extension methods.

Monitoring for signs of probabilistic or time-based logic is essential. Alerts should be established for date checks and unusual calls to Process.Kill() within dependencies. For industrial settings, verifying the integrity of PLC commands through write-confirmation checks and monitoring success rates can mitigate risks associated with failed write operations.

Lastly, organizations should enforce rigorous supply chain policies. This includes limiting privileges for package installations, requiring comprehensive code reviews for third-party libraries, and implementing strict change control measures for operational technology components.

By adopting these strategies, organizations can fortify their software supply chains and reduce vulnerability to hidden malicious logic. The ongoing threat from this campaign underscores the need for vigilance in software development practices, as supply-chain attacks continue to evolve and exploit trusted code for destructive ends.