mitigations.md

Mitigation Strategies Analysis for jordansissel/fpm

Mitigation Strategy: Strictly Validate User-Provided Inputs

• Description:

  1. Identify fpm Input Points: Pinpoint all locations where user-provided data is used as input to fpm commands. This includes command-line arguments passed to fpm (like --name, --version, --description, --input-type, --output-type, file paths, etc.), data read from configuration files that influence fpm behavior, and any environment variables used to configure fpm commands.
  2. Define Validation Rules for fpm Inputs: For each fpm input point, define strict validation rules based on fpm's expected input formats and limitations. Consult fpm documentation to understand valid input types, formats, and any restrictions. For example, validate package names against allowed characters and lengths as per package format specifications, validate versions against semantic versioning, and ensure file paths are within allowed directories and formats.
  3. Implement Input Validation Before Calling fpm: Integrate input validation checks into your application code before executing fpm commands. Use appropriate validation libraries or functions in your programming language to enforce the defined rules on the data intended to be passed to fpm.
  4. Handle Invalid Inputs and Prevent fpm Execution: Implement robust error handling for invalid inputs. When validation fails, reject the input, log the error with details (including the invalid input), and provide informative error messages. Crucially, prevent the execution of the fpm command if input validation fails. Do not pass invalid data to fpm in any circumstance.
  5. Canonicalize Paths Passed to fpm: When specifying file paths to fpm (e.g., using --input-files, --directories), use path canonicalization techniques before passing them to fpm. This resolves symbolic links and ensures that paths point to the intended locations within allowed directories, preventing path traversal attempts that could be exploited by fpm if it doesn't perform sufficient internal path sanitization.

• Threats Mitigated:

  • Command Injection via fpm Arguments (High Severity): Malicious user input injected into fpm command-line arguments can be interpreted as commands by fpm or the underlying shell, leading to arbitrary command execution on the build system.
  • Path Traversal via fpm File Paths (High Severity): Unvalidated file paths provided to fpm can allow attackers to specify files outside of the intended build directory, potentially leading to fpm packaging sensitive system files or manipulating files outside the intended build context if fpm itself has path traversal vulnerabilities.
  • Denial of Service (DoS) via Malformed fpm Inputs (Medium Severity): Maliciously crafted inputs (e.g., extremely long strings, special characters in package names or descriptions) can cause fpm to crash, hang, or consume excessive resources, leading to a denial of service of the packaging process.
  • Configuration Injection into fpm (Medium Severity): Manipulating fpm configuration options through unvalidated input could lead to unintended or insecure package configurations being generated by fpm.

• Impact:

  • Command Injection via fpm Arguments: High Reduction - Thorough input validation specifically targeting fpm arguments significantly reduces the risk of command injection by preventing malicious commands from being constructed and passed to fpm.
  • Path Traversal via fpm File Paths: High Reduction - Path validation and canonicalization applied before passing paths to fpm effectively prevent path traversal vulnerabilities related to fpm's file handling.
  • DoS via Malformed fpm Inputs: Medium Reduction - Input validation can mitigate some input-based DoS attacks against fpm by rejecting malformed or excessively large inputs before they reach fpm, but might not prevent all DoS scenarios within fpm itself.
  • Configuration Injection into fpm: High Reduction - Validating configuration-related inputs passed to fpm prevents attackers from manipulating package settings through input manipulation of fpm's options.

• Currently Implemented: Partially implemented. Basic regex checks are used for package name and version validation before calling fpm in the application's packaging script.

• Missing Implementation: Missing detailed validation for file paths provided to fpm (especially when specifying directories to include using --directories or similar options), descriptions, and other metadata fields passed as arguments to fpm. Canonicalization of paths before passing them to fpm is not currently implemented. Validation of configuration file inputs that might influence fpm execution is also missing.

Mitigation Strategy: Control Script Execution during Package Build (via fpm options)

• Description:

  1. Minimize Script Usage with fpm: Reduce the reliance on preinstall, postinstall, prerm, and postrm scripts within packages built by fpm. Explore alternative fpm options or configuration methods to achieve desired setup tasks without relying on external scripts. For example, use fpm's built-in features for setting file permissions, ownership, or configuration file management instead of scripts where possible.
  2. Carefully Review Scripts Used with fpm: If scripts are deemed necessary for package creation with fpm, carefully review and audit the content of these scripts before using them with fpm. Ensure they are written securely and follow secure coding practices. Avoid including or executing untrusted or dynamically generated code within these scripts that are passed to fpm for inclusion in packages.
  3. Static Analysis of fpm Package Scripts: Perform static analysis on any package scripts that are intended to be used with fpm (and included in packages) to identify potential security vulnerabilities before using fpm to build the package. Use static analysis tools appropriate for the scripting language used (e.g., ShellCheck for shell scripts).
  4. Restrict Script Permissions within fpm (if possible): If fpm offers options to control the permissions under which package scripts are executed during installation, utilize these options to restrict script permissions to the minimum necessary. Avoid running scripts as root unless absolutely required and minimize the scope of root privileges even then. Consult fpm documentation for script execution permission controls.
  5. Avoid Passing Untrusted Scripts to fpm: Never pass untrusted or externally sourced scripts to fpm for inclusion in packages without thorough security review and validation. Treat scripts used with fpm as critical components that can directly impact system security.

• Threats Mitigated:

  • Malicious Package Scripts Included via fpm (High Severity): If malicious or compromised scripts are inadvertently or intentionally included in packages via fpm's script inclusion mechanisms, these scripts can execute arbitrary code on the target system during package installation or removal, leading to system compromise, data breaches, or denial of service.
  • Vulnerabilities in Package Scripts Handled by fpm (Medium Severity): Poorly written package scripts that are included via fpm can contain vulnerabilities (e.g., command injection, path traversal) that can be exploited by attackers after package installation.

• Impact:

  • Malicious Package Scripts Included via fpm: High Reduction - Carefully controlling and reviewing scripts used with fpm, and minimizing their use in favor of fpm's built-in features, significantly reduces the risk of malicious scripts being included in packages through fpm.
  • Vulnerabilities in Package Scripts Handled by fpm: Medium Reduction - Static analysis and secure coding practices for scripts intended for use with fpm help identify and mitigate vulnerabilities in package scripts before they are packaged by fpm.

• Currently Implemented: Partially implemented. Package scripts are used sparingly with fpm, and basic manual reviews are performed on scripts before using them with fpm. Static analysis and explicit permission controls within fpm for scripts are not implemented.

• Missing Implementation: Formalized script review process specifically for scripts used with fpm, static analysis of these scripts, and investigation/implementation of any fpm options to restrict script execution permissions are missing. Continued efforts to minimize script usage with fpm should be prioritized.

Mitigation Strategy: Enforce Secure File Permissions in Packages (via fpm options)

• Description:

  1. Define Secure Default Permissions for fpm Packages: Establish secure default file permissions for files and directories within packages generated by fpm, adhering to the principle of least privilege. Determine appropriate default permissions for different types of files (executables, configuration files, data files, directories) within your application packages.
  2. Configure fpm to Set Permissions Explicitly: Utilize fpm's command-line options or configuration settings to explicitly set file permissions during package creation. Consult fpm documentation for options like --directories-mode, --files-mode, --config-files-mode, and similar permission-related flags. Ensure that directories have appropriate execute permissions for traversal, and files have read/write permissions only where necessary.
  3. Use fpm Options to Set Ownership: Utilize fpm options to set appropriate ownership (user and group) for files and directories within packages. Use options like --directories-owner, --files-owner, --directories-group, --files-group to control ownership. Ensure that ownership aligns with the principle of least privilege and application security requirements.
  4. Avoid Overly Permissive Permissions in fpm Configurations: When configuring fpm's permission settings, actively avoid setting overly permissive permissions like 777 (world-writable and executable) unless absolutely required and thoroughly justified by a specific security requirement.
  5. Regularly Review fpm Permission Configurations: Periodically review the fpm configurations used for setting file permissions and ownership to ensure they remain secure, aligned with security best practices, and consistent with organizational security policies.

• Threats Mitigated:

  • Unauthorized Access to Package Files (Medium Severity): Overly permissive file permissions set by fpm in generated packages can allow unauthorized users or processes on the target system to read, modify, or execute files within the installed package, potentially leading to information disclosure, data tampering, or privilege escalation.
  • Privilege Escalation via Incorrect Package Permissions (Medium Severity): Incorrect file permissions on executables or configuration files within packages created by fpm can be exploited for privilege escalation attacks on the target system.

• Impact:

  • Unauthorized Access to Package Files: Medium Reduction - Enforcing secure file permissions using fpm's options significantly reduces the risk of unauthorized access to package files after installation.
  • Privilege Escalation via Incorrect Package Permissions: Medium Reduction - Correctly setting permissions using fpm helps prevent certain types of privilege escalation attacks related to file permissions within installed packages.

• Currently Implemented: Basic default permissions are applied by fpm based on the system defaults, but explicit configuration of permissions and ownership using fpm options is not systematically performed.

• Missing Implementation: A defined set of secure default permissions and ownership settings for packages needs to be established and then explicitly configured in fpm using its permission and ownership related options. Regular reviews of these fpm configurations should be implemented.

Mitigation Strategy: Obtain fpm Tool from Trusted Sources

• Description:

  1. Use Official and Trusted Sources for fpm Installation: Install the fpm tool exclusively from official and trusted sources. The primary trusted source is the official GitHub repository (https://github.com/jordansissel/fpm) for verifying releases and potentially building from source. Package managers of reputable Linux distributions (e.g., apt, yum, dnf) are also generally considered trusted sources for pre-built fpm packages.
  2. Verify Integrity of fpm Downloads: When downloading fpm from any source (even trusted ones), verify the integrity of the downloaded file using checksums or digital signatures provided by the source. For GitHub releases, check for signatures or checksums provided alongside release binaries. For package manager installations, rely on the package manager's built-in integrity verification mechanisms. Compare the downloaded file's checksum against the official checksum to ensure it hasn't been tampered with during download or distribution.
  3. Avoid Unofficial or Third-Party fpm Sources: Strictly avoid downloading or installing fpm from unofficial websites, third-party repositories, or file-sharing platforms. These sources may distribute compromised, backdoored, or outdated versions of the fpm tool.

• Threats Mitigated:

  • Compromised fpm Tool Itself (High Severity): Downloading fpm from untrusted sources significantly increases the risk of obtaining a compromised version of the tool. A compromised fpm tool could be backdoored to inject malicious code into generated packages during the packaging process, or compromise the build system itself when executed. This is a direct threat introduced by the source of the fpm tool.
  • Supply Chain Attacks Targeting fpm Tool (Medium Severity): Using untrusted sources for fpm can be a point of entry for supply chain attacks, where attackers distribute malicious software by compromising the distribution channels of tools like fpm.

• Impact:

  • Compromised fpm Tool Itself: High Reduction - Obtaining fpm exclusively from trusted sources significantly reduces the risk of using a compromised fpm tool and thus reduces the risk of malicious packages being generated or the build system being compromised by the fpm tool itself.
  • Supply Chain Attacks Targeting fpm Tool: Medium Reduction - Using trusted sources is a crucial step in mitigating supply chain risks specifically related to the fpm tool and ensuring the tool itself is not a source of compromise.

• Currently Implemented: Yes. fpm is installed using the system package manager (apt) which is considered a trusted source for system packages.

• Missing Implementation: N/A - Currently implemented. However, it's important to periodically re-verify the source and installation method to ensure continued adherence to this strategy and to re-evaluate trust in the installation source if circumstances change. Also, ensure that any updates to fpm are also sourced from trusted locations.