threat-modeling.md

Threat Model Analysis for serde-rs/serde

Threat: Unsafe Deserialization of Untrusted Data

Description: An attacker sends maliciously crafted data to the application. This data exploits vulnerabilities within Serde or a format-specific deserializer during the deserialization process. The attacker aims to cause severe consequences like arbitrary code execution or critical application failure. They achieve this by crafting input that triggers memory safety issues (e.g., buffer overflows, use-after-free) or logic errors within the deserialization code.

Impact: Denial of Service (DoS), Remote Code Execution (RCE), data corruption, critical application failure, potential for complete system compromise.

Serde Component Affected: Format-specific deserializers (e.g., serde_json::from_str, serde_yaml::from_reader), core Serde library if vulnerabilities exist in its core deserialization logic.

Risk Severity: Critical

Mitigation Strategies:

• Strict Input Validation (Post-Deserialization): While Serde handles format parsing, implement robust validation after deserialization to enforce application-level data integrity and constraints. Do not solely rely on Serde for security.
• Secure Deserialization Libraries: Utilize well-vetted and actively maintained format-specific deserializers. Stay informed about security advisories for Serde and its ecosystem.
• Sandboxing Deserialization: Isolate the deserialization process within a sandboxed environment, especially when handling highly untrusted input, to limit the impact of potential exploits.
• Fuzzing and Security Testing: Employ fuzzing and rigorous security testing specifically targeting deserialization endpoints and data formats to proactively identify vulnerabilities.
• Memory Safety Best Practices: Adhere to Rust's memory safety principles and conduct thorough code reviews to minimize memory safety issues in any custom deserialization handling or data processing after Serde.

Threat: Denial of Service (DoS) via Resource Exhaustion during Deserialization

Description: An attacker crafts and sends excessively large, deeply nested, or computationally expensive data to the application for deserialization. This input is designed to consume excessive server resources (CPU, memory, time) during the deserialization process, overwhelming the application and causing it to become unresponsive or crash. Attackers might exploit format features like deeply nested structures in JSON/YAML or extremely long strings to trigger resource exhaustion.

Impact: Application unavailability, severe performance degradation, resource exhaustion leading to service disruption, potential cascading failures in dependent systems.

Serde Component Affected: Format-specific deserializers (parsing logic within serde_json, serde_yaml, etc.), potentially core Serde if it lacks built-in resource limits for deserialization.

Risk Severity: High

Mitigation Strategies:

• Input Size Limits: Implement strict limits on the maximum size of input data allowed for deserialization to prevent processing of excessively large payloads.
• Deserialization Timeouts: Enforce timeouts for deserialization operations to prevent indefinite processing and resource holding.
• Resource Quotas and Monitoring: Implement resource quotas (e.g., memory limits per request) for deserialization processes and monitor resource usage to detect and mitigate DoS attempts.
• Rate Limiting: Apply rate limiting to endpoints that handle deserialization of untrusted data to restrict the frequency of potentially malicious requests.
• Efficient Data Formats: Consider using data formats that are less susceptible to resource exhaustion during parsing if performance and security are critical.

Threat: Format-Specific Deserialization Vulnerabilities

Description: An attacker exploits known or zero-day security vulnerabilities residing within the format-specific deserialization libraries that Serde relies upon (e.g., serde_json, serde_yaml, serde_cbor). The attacker crafts input data specifically designed to trigger these vulnerabilities in the underlying parsing logic, bypassing Serde's core and directly attacking the format library. This can lead to critical consequences like memory corruption or remote code execution within the format library's context.

Impact: Denial of Service (DoS), Remote Code Execution (RCE), data corruption, information disclosure, potential for complete system compromise, depending on the severity of the vulnerability in the format library.

Serde Component Affected: Format-specific deserialization libraries (e.g., serde_json, serde_yaml, serde_cbor) - indirectly affects applications using Serde through these dependencies.

Risk Severity: Critical

Mitigation Strategies:

• Immediate Dependency Updates: Prioritize and promptly update Serde and all format-specific deserialization dependencies to the latest versions as soon as security patches are released.
• Proactive Dependency Scanning: Implement automated dependency scanning tools to continuously monitor for known vulnerabilities in Serde and its dependencies.
• Choose Well-Maintained Libraries: Select and utilize format-specific libraries that are actively maintained, have a strong security track record, and a responsive security team.
• Security Vulnerability Monitoring: Actively monitor security advisories, vulnerability databases, and security mailing lists related to Rust crates and Serde-related projects to stay informed about potential threats.

Threat: Vulnerabilities in Serde or its Dependencies

Description: Serde itself, or any of its direct or indirect dependencies (including format-specific libraries), may contain undiscovered or publicly disclosed security vulnerabilities. An attacker can exploit these vulnerabilities if the application is using a vulnerable version of Serde or its dependencies. This could be a flaw in Serde's core logic, a format deserializer, or a transitive dependency within the Serde ecosystem.

Impact: All consequences associated with deserialization and serialization vulnerabilities, ranging from Denial of Service to Remote Code Execution, data corruption, and potential for complete system compromise, depending on the nature and severity of the vulnerability.

Serde Component Affected: Core Serde library (serde-rs/serde), format-specific libraries (e.g., serde_json, serde_yaml), transitive dependencies within the Serde dependency tree.

Risk Severity: Critical

Mitigation Strategies:

• Aggressive Dependency Updates: Establish a process for aggressively and regularly updating Serde and all its dependencies to the latest versions to ensure timely patching of known vulnerabilities.
• Automated Dependency Scanning: Integrate automated dependency scanning tools into the development pipeline to continuously detect and alert on known vulnerabilities in project dependencies.
• Security Monitoring and Alerts: Subscribe to security advisories, vulnerability databases, and security alerts for Rust crates and Serde-related projects to proactively monitor for and respond to emerging threats.
• Reproducible Builds and Verification: Implement reproducible build processes and dependency verification mechanisms to ensure the integrity and authenticity of dependencies and mitigate supply chain risks.

Threat: Malicious Code Injection via Serde Dependency Compromise

Description: An attacker compromises the supply chain specifically targeting Serde or one of its critical dependencies. This could involve compromising the crates.io repository, developer accounts of Serde maintainers or dependency maintainers, or build infrastructure used for Serde or its dependencies. The attacker injects malicious code into a Serde library or a dependency, which is then distributed to applications that depend on it through standard dependency management channels. This injected malicious code can execute arbitrary commands within the application's context upon inclusion.

Impact: Remote Code Execution (RCE), data theft, complete application compromise, supply chain compromise affecting all applications using the compromised dependency, widespread security incident potential.

Serde Component Affected: Entire Serde ecosystem, including core library, format-specific libraries, and potentially transitive dependencies, and the crates.io distribution mechanism.

Risk Severity: Critical

Mitigation Strategies:

• Dependency Verification and Checksums: Utilize tools and practices to verify the integrity and authenticity of downloaded dependencies, including checking crates.io checksums and potentially using cryptographic signing if available.
• Robust Supply Chain Security: Implement comprehensive supply chain security practices, including dependency scanning, vulnerability monitoring, secure software development lifecycle (SSDLC) principles, and secure build pipelines.
• Principle of Least Privilege and Sandboxing: Run applications with the principle of least privilege to limit the impact of compromised dependencies. Consider sandboxing or isolating application components to contain potential breaches.
• Regular Security Audits and Reviews: Conduct regular security audits of dependencies, build processes, and application code to identify and mitigate potential supply chain risks.
• Dependency Pinning and Review: Consider pinning dependency versions and thoroughly reviewing dependency updates before incorporating them into the application to detect and prevent malicious inclusions.