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Threat Model Analysis for mesonbuild/meson

Threat: Threat 1: Malicious meson.build Injection

  • Description: An attacker gains write access to the project's source repository (or a dependency's repository) and modifies a meson.build file (or an included file, like a .wrap file) to include malicious code. This code is executed during Meson's configuration or build phases. The attacker leverages Meson's features like run_command(), custom targets, or manipulates dependency resolution.
    • Impact:
      • Compromised build artifacts (executables, libraries) with backdoors/malware.
      • Arbitrary code execution on the build machine, compromising the build environment.
      • Potential leakage of sensitive information from the build environment.
    • Affected Meson Component: meson.build files (core configuration), run_command() function, custom target definitions, dependency resolution (including wrap files and subprojects).
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strict Code Review: Mandatory, thorough code reviews for all meson.build changes and included files.
      • Version Control Security: Strong access controls, audit trails, and multi-factor authentication for repository access.
      • Dependency Pinning: Specify exact versions of all dependencies (including subprojects).
      • Checksum Verification: Use checksums (e.g., in wrap files) to verify dependency integrity.
      • Least Privilege: Run the build process with minimal privileges. Avoid running Meson as root.
      • Sandboxed Build Environments: Use containers (Docker, Podman) or VMs to isolate the build process.

Threat: Threat 2: Compromised WrapDB/Custom Wrap Provider

  • Description: The official Meson WrapDB (or a custom wrap provider) is compromised. An attacker modifies wrap file definitions to point to malicious dependencies or inject malicious build instructions directly into the wrap file.
    • Impact: The build fetches and uses compromised dependencies, resulting in malicious code in the final build. The attacker can also inject malicious build steps.
    • Affected Meson Component: WrapDB integration, meson wrap command, custom wrap providers, dependency resolution using wrap files.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • HTTPS Enforcement: Ensure WrapDB is always accessed via HTTPS (default, but verify).
      • Wrap File Checksums: Meson automatically verifies wrap file checksums. Do not disable this.
      • Secure Custom Wrap Providers: If using a custom provider, ensure it's securely hosted, uses HTTPS, and has strong access controls. Audit regularly.
      • Dependency Mirroring: Mirror critical dependencies locally to reduce reliance on external providers.
      • Regular Audits: Periodically audit the security of the wrap provider (official or custom).

Threat: Threat 3: Man-in-the-Middle (MitM) during Dependency Fetching (Meson-managed fetches)

  • Description: An attacker intercepts network traffic during dependency fetching specifically when Meson is managing the fetch. This is most relevant when using features like subproject() with a URL, or custom fetch commands within run_command() that don't inherently provide strong security. (If a project uses, say, curl with HTTPS and checksum verification within a run_command(), that's less of a direct Meson threat, as the security is handled by curl.)
    • Impact: The attacker substitutes malicious dependencies, leading to compromised build artifacts.
    • Affected Meson Component: Dependency resolution mechanisms, subproject() (when fetching from URLs), run_command() (when used for unprotected fetching).
    • Risk Severity: High
    • Mitigation Strategies:
      • HTTPS Everywhere: Always use HTTPS for fetching dependencies within Meson configurations.
      • Checksum Verification: Verify checksums whenever possible, especially for dependencies fetched via subproject() or custom commands.
      • Dependency Pinning: Pinning helps ensure the same version is fetched, reducing the MitM attack window.
      • Avoid Unsafe Fetching in run_command(): If using run_command() for fetching, ensure the command itself uses secure protocols and verifies integrity (e.g., use curl with HTTPS and checksumming). Prefer built-in Meson mechanisms when possible.

Threat: Threat 4: Improper install Target Permissions

  • Description: install targets in meson.build are misconfigured, installing files with excessive permissions (e.g., world-writable) or to unintended locations, potentially overwriting system files.
    • Impact: Attackers can exploit these permissions to gain elevated privileges or modify critical system files.
    • Affected Meson Component: install target definitions, meson install command.
    • Risk Severity: High
    • Mitigation Strategies:
      • Principle of Least Privilege: Install files with minimal necessary permissions. Avoid overly permissive modes.
      • Careful Path Selection: Choose installation paths carefully. Avoid system-wide locations unless necessary. Use prefix and DESTDIR correctly.
      • Testing: Test installation in a sandboxed environment (e.g., a container).
      • Review: Thoroughly review all install target configurations.

Threat: Threat 5: Custom Commands with Elevated Privileges

  • Description: meson.build uses run_command() to execute commands with elevated privileges (e.g., via sudo). An attacker modifying meson.build can inject malicious code.
    • Impact: Attacker gains complete control over the build system.
    • Affected Meson Component: run_command() function.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Avoid Privilege Escalation: Do not use sudo or similar within run_command().
      • Least Privilege Principle: Run the build process with the lowest possible privileges.
      • Sandboxing: If elevated privileges are absolutely unavoidable, isolate the task in a tightly controlled sandbox.
      • Code Review: Scrutinize any use of run_command() for privilege escalation risks.

Threat: Threat 6: Masquerading Legitimate Dependency (Direct Meson Resolution)

  • Description: An attacker publishes a malicious package with the same name as a legitimate dependency. If the project's Meson configuration doesn't specify a precise version or checksum, and Meson is responsible for resolving the dependency, Meson might fetch the malicious package. This is distinct from a general supply chain attack; this is about Meson's resolution logic.
    • Impact: The build incorporates the malicious dependency, leading to compromised artifacts.
    • Affected Meson Component: Dependency resolution, wrap files (if used and not properly configured), external project fetching managed by Meson.
    • Risk Severity: High
    • Mitigation Strategies:
      • Dependency Pinning: Specify the exact version of each dependency in meson.build or the wrap file.
      • Checksum Verification: Use checksums (e.g., in wrap files) to verify dependency integrity.
      • Private Repositories: For sensitive projects, use private, trusted repositories.
      • SCA Tools: Use Software Composition Analysis tools to identify vulnerabilities and potentially malicious packages, but understand this is a broader mitigation, not solely a Meson-specific one. The core issue here is Meson's resolution without sufficient verification.