Skip to content

Latest commit

 

History

History
42 lines (35 loc) · 6.29 KB

attack-surface.md

File metadata and controls

42 lines (35 loc) · 6.29 KB

Attack Surface Analysis for faisalman/ua-parser-js

Attack Surface: Regular Expression Denial of Service (ReDoS) Attacks

  • Description: ua-parser-js relies heavily on regular expressions to parse User-Agent strings. Maliciously crafted User-Agent strings can exploit vulnerabilities in these regular expressions, causing excessive backtracking and leading to a denial-of-service (DoS) condition. This can consume excessive CPU resources, potentially crashing the application or server.
  • How ua-parser-js Contributes: The library's core functionality is parsing User-Agent strings, which inherently involves regular expression matching. The complexity and variety of User-Agent strings make it a potential target for ReDoS attacks.
  • Example: An attacker could send a crafted User-Agent string with a pattern designed to trigger worst-case performance in the regular expression engine, causing the parsing process to take an extremely long time, consuming excessive CPU and memory.
  • Impact: Denial of Service (DoS), application crashes, server unresponsiveness.
  • Risk Severity: High (Potentially Critical, depending on the application's reliance on ua-parser-js and the server's resources).
  • Mitigation Strategies:
    • Input Validation: Implement strict input validation on User-Agent strings before they are passed to ua-parser-js. This includes limiting the length of the User-Agent string to a reasonable maximum (e.g., 256-512 characters). Reject overly long or complex strings.
    • Timeouts: Wrap calls to ua-parser-js with a timeout mechanism. If parsing takes longer than a predefined threshold (e.g., a few milliseconds), terminate the operation and log the event.
    • Regular Expression Auditing: Regularly review and update the ua-parser-js library to the latest version. The library maintainers actively address known ReDoS vulnerabilities. Consider using static analysis tools to identify potentially vulnerable regular expressions within the library's code (though this requires significant expertise).
    • Resource Monitoring: Monitor CPU and memory usage associated with User-Agent parsing. Unusual spikes can indicate a ReDoS attack.
    • Web Application Firewall (WAF): Configure a WAF to detect and block known malicious User-Agent patterns associated with ReDoS attacks.
    • Input Sanitization (Careful Consideration): While not a direct mitigation for ReDoS, carefully consider sanitizing the User-Agent string before passing it to ua-parser-js. However, be extremely cautious, as improper sanitization can introduce vulnerabilities or break legitimate User-Agent parsing. Focus on removing obviously malicious characters or patterns rather than attempting broad sanitization. This is a secondary measure, not a primary defense.

Attack Surface: Data Exposure (Indirect - through incorrect usage)

  • Description: While ua-parser-js itself doesn't directly expose data, incorrect usage of the library can lead to unintentional information leakage. If the parsed User-Agent data (e.g., browser version, operating system) is logged, displayed, or used in security-sensitive contexts without proper sanitization or consideration, it could reveal information about users or the system.
  • How ua-parser-js Contributes: The library provides detailed information extracted from the User-Agent string. The misuse of this information is the vulnerability.
  • Example: Logging the full User-Agent string to an insecure location, or using it to make authorization decisions without considering spoofing, could expose user information or allow attackers to bypass security measures. Another example: displaying the raw User-Agent string on a public-facing page could expose users to fingerprinting.
  • Impact: Information disclosure, potential privacy violations, potential for targeted attacks based on revealed user agent information.
  • Risk Severity: Medium to High (depending on the sensitivity of the data and how it's used).
  • Mitigation Strategies:
    • Minimal Logging: Only log the essential information from the User-Agent string that is needed for debugging or analytics. Avoid logging the entire raw string.
    • Data Masking/Anonymization: If you need to store or display User-Agent data, consider masking or anonymizing sensitive parts (e.g., replacing specific version numbers with generic ones).
    • Avoid Security Decisions Based Solely on User-Agent: Do not rely solely on the User-Agent string for security-critical decisions (e.g., authentication, authorization). User-Agent strings are easily spoofed.
    • Careful Output Encoding: If displaying User-Agent information in a web page, ensure proper HTML encoding to prevent Cross-Site Scripting (XSS) vulnerabilities.

Attack Surface: Dependency Vulnerabilities (Indirect)

  • Description: Like any library, ua-parser-js itself, or its dependencies, could have vulnerabilities. These vulnerabilities could be exploited if an attacker can influence the User-Agent string.
  • How ua-parser-js Contributes: The library is a dependency, and any vulnerabilities within it become part of the application's attack surface.
  • Example: A hypothetical vulnerability in a regular expression used by ua-parser-js could be exploited by a specially crafted User-Agent string, leading to arbitrary code execution.
  • Impact: Varies widely depending on the vulnerability, potentially ranging from information disclosure to remote code execution.
  • Risk Severity: High to Critical (depending on the vulnerability).
  • Mitigation Strategies:
    • Keep Updated: Regularly update ua-parser-js to the latest version to receive security patches. Use dependency management tools (e.g., npm, yarn) to track and update dependencies.
    • Vulnerability Scanning: Use software composition analysis (SCA) tools to scan your project's dependencies for known vulnerabilities.
    • Dependency Auditing: Periodically review the dependencies of ua-parser-js itself to understand the potential attack surface.