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Threat Model Analysis for touchlab/kermit

Threat: Threat 1: Sensitive Data Exposure via Unprotected LogWriter Output (Kermit's Default Behavior)

  • Description: Kermit, by default, provides basic LogWriter implementations (like CommonWriter, NSLogWriter, OSLogWriter) that output log messages directly to standard output (console), system logs, or platform-specific logging facilities. These default writers do not perform any sanitization, redaction, or encryption. If developers use these default writers without modification and log sensitive data, that data will be exposed in plain text wherever the logs are directed. The attacker gains access to the output destination (console, system log files, etc.).
    • Impact:
      • Confidentiality Breach: Exposure of sensitive data (passwords, API keys, PII) leading to severe consequences (identity theft, financial loss, system compromise).
    • Kermit Component Affected:
      • Default LogWriter implementations: CommonWriter, NSLogWriter, OSLogWriter, and any other LogWriter that doesn't explicitly handle sensitive data. The core logging functions (Logger.v(), Logger.d(), etc.) are the entry points, but the default writers are the direct source of the vulnerability.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • 1. Mandatory Custom LogWriter for Sensitive Data: Never rely solely on the default LogWriter implementations in production, especially if the application handles any sensitive data. Always implement a custom LogWriter that intercepts log messages before they are written. This custom writer must perform robust data masking/redaction using regular expressions, a dedicated PII redaction library, or a lookup table. This is the primary and essential mitigation.
      • 2. Code Reviews and Static Analysis: Enforce code reviews and use static analysis tools to detect any use of the default LogWriter implementations without accompanying redaction logic. This acts as a secondary check.
      • 3. Secure Configuration: If a custom LogWriter sends logs to a remote service, ensure that communication is encrypted (HTTPS) and that the receiving service has appropriate access controls and security measures.
      • 4. Log Level Restrictions: Enforce strict log level policies. Prohibit the use of Verbose and Debug levels in production environments.

Threat: Threat 2: Log Injection IF Custom LogWriter is Vulnerable

  • Description: While Kermit itself doesn't directly handle input validation, if a developer creates a custom LogWriter that is vulnerable to injection attacks, this becomes a Kermit-related threat. For example, if the custom LogWriter takes the log message string and directly inserts it into an SQL query, HTML output, or a shell command without proper sanitization or escaping, an attacker could inject malicious code. This is a vulnerability in the custom LogWriter, but it's a direct consequence of extending Kermit.
    • Impact:
      • Code Execution: Depending on the vulnerability in the custom LogWriter, the attacker might be able to execute arbitrary code on the system where the logs are being processed.
      • Data Corruption/Deletion: If the custom LogWriter interacts with a database, the attacker could inject SQL commands to modify or delete data.
      • Cross-Site Scripting (XSS): If the custom LogWriter outputs logs to a web interface, the attacker could inject JavaScript code, leading to XSS attacks.
    • Kermit Component Affected:
      • Custom LogWriter implementations. The vulnerability lies specifically in the developer-written code within the LogWriter.
    • Risk Severity: High
    • Mitigation Strategies:
      • 1. Secure Coding Practices for Custom LogWriter: Developers must follow secure coding practices when creating custom LogWriter implementations. This includes:
        • Input Validation and Sanitization: Thoroughly validate and sanitize all data within the LogWriter before using it in any potentially dangerous context (e.g., SQL queries, HTML output, shell commands).
        • Output Encoding: Use appropriate output encoding techniques (e.g., HTML encoding, URL encoding) to prevent injection attacks.
        • Parameterized Queries: If interacting with a database, use parameterized queries or prepared statements to prevent SQL injection.
        • Avoid Shell Commands: Avoid using shell commands if possible. If necessary, use secure APIs for interacting with the operating system.
      • 2. Code Reviews: Mandatory code reviews of all custom LogWriter implementations, with a specific focus on security vulnerabilities.
      • 3. Security Testing: Perform penetration testing and security audits to identify and address any vulnerabilities in custom LogWriter implementations.