attack-surface.md

Attack Surface Analysis for jakewharton/timber

Attack Surface: 1. Information Disclosure via Verbose Logging (DebugTree in Production)

• Description: Timber's DebugTree, designed for development, outputs verbose logs including class and method names. Leaving DebugTree active in production directly exposes internal application details through device logs.
• How Timber Contributes: Timber provides DebugTree as a readily available default, and its ease of use can lead to developers unintentionally deploying it in production builds, failing to switch to more secure logging configurations.
• Example: A production application uses Timber.plant(new DebugTree()). Logcat captures detailed debug logs including sensitive data accidentally logged during development, internal paths, and class structures. An attacker gaining access to device logs can extract this information to understand the application's inner workings and potentially identify vulnerabilities.
• Impact: Confidentiality breach, significant aid for reverse engineering efforts, exposure of potentially sensitive data logged in debug statements, increased attack surface for further exploitation.
• Risk Severity: High
• Mitigation Strategies:
  • Conditional Tree Planting: Utilize build variants or conditional code to ensure DebugTree (or any verbose development-focused Tree) is exclusively planted in debug builds and never in release/production builds.
  • Production Tree Configuration: Explicitly configure a production Tree that is designed for minimal logging, focusing only on critical errors or security-relevant events, and avoids verbose output.
  • Automated Build Checks: Implement automated checks in the build process to verify that DebugTree or similar verbose Trees are not included in production builds, failing the build if detected.

Attack Surface: 2. Custom Tree Vulnerabilities

• Description: Timber's extensibility allows for custom Tree implementations. If these custom Tree classes are not developed with security in mind, they can introduce significant vulnerabilities directly through their logging actions.
• How Timber Contributes: Timber's core design encourages the creation of custom Tree classes to handle diverse logging needs. This powerful feature directly introduces the risk of developers creating insecure custom logging components if they lack security awareness or fail to implement secure coding practices within their Tree implementations.
• Example: A developer creates a custom FileLoggingTree to write logs to a file. This Tree is implemented without proper input sanitization and is vulnerable to log injection. An attacker can craft malicious log messages that, when processed by the custom Tree, execute arbitrary commands or overwrite critical files on the device. Another example is a custom NetworkTree that insecurely stores or transmits API keys, exposing them to potential interception.
• Impact: Potentially critical depending on the vulnerability introduced in the custom Tree. Could lead to: Remote Code Execution (via log injection), Confidentiality breach (via insecure log storage or transmission), Data Integrity issues (via log manipulation), or Denial of Service (via resource exhaustion in the custom Tree).
• Risk Severity: High to Critical (depending on the specific vulnerability introduced in the custom Tree and the potential impact).
• Mitigation Strategies:
  • Secure Coding Practices for Custom Trees: Mandate and enforce secure coding practices during the development of all custom Tree implementations. This includes input sanitization, secure file handling, secure network communication, and proper error handling.
  • Security Code Review for Custom Trees: Require thorough security code reviews specifically for all custom Tree implementations before deployment. Focus on identifying potential vulnerabilities related to logging actions, data handling, and resource access.
  • Principle of Least Privilege for Custom Trees: Design custom Tree implementations to operate with the minimum necessary permissions and access rights required for their logging functionality, limiting the potential impact of a vulnerability.
  • Security Testing for Custom Trees: Conduct security testing, including penetration testing and vulnerability scanning, specifically targeting custom Tree implementations to identify and remediate potential weaknesses.