attack-surface.md

Attack Surface Analysis for valyala/fasthttp

Attack Surface: Header Injection

Description: Attackers inject malicious headers into HTTP requests. fasthttp's performance-oriented design, prioritizing speed, might lead to less strict header validation during parsing. This can be exploited if application logic improperly handles or reflects these unsanitized headers. fasthttp Contribution: fasthttp's focus on speed over deep inspection can make it more reliant on application-level header sanitization. Lack of strict built-in header validation in fasthttp increases the risk if developers don't implement robust checks. Example: Injecting X-Forwarded-Host: malicious.example.com header. If the application uses this header to construct URLs without validation, it can lead to open redirection to malicious.example.com. Impact: HTTP Response Splitting/Smuggling, Cache Poisoning, Open Redirection, potentially Cross-Site Scripting (XSS) if headers are reflected. Risk Severity: High Mitigation Strategies:

• Strict Header Validation: Implement rigorous input validation and sanitization for all incoming headers within the application logic before any further processing or reflection.
• Avoid Direct Header Reflection: Minimize or eliminate directly reflecting request headers in responses. If necessary, use secure encoding and sanitization functions.
• Secure Header Handling Libraries: Utilize libraries or functions specifically designed for secure header manipulation to prevent injection vulnerabilities in application code.

Attack Surface: URL Parsing Vulnerabilities (Path Traversal)

Description: Attackers manipulate URL paths to access unauthorized files or resources. While fasthttp provides URL parsing, its speed focus might encourage developers to rely on its output without sufficient application-level path sanitization, leading to vulnerabilities. fasthttp Contribution: fasthttp's efficient URL parsing, while beneficial for performance, doesn't inherently prevent path traversal. Developers must implement path sanitization on top of fasthttp's parsing results. Example: An application uses c.URI().Path() to construct file paths without validation. A request with /../../etc/passwd could expose sensitive system files if the application directly uses this path for file access. Impact: Unauthorized access to sensitive files, data breaches, information disclosure, potentially remote code execution if combined with other weaknesses. Risk Severity: High Mitigation Strategies:

• Robust Path Sanitization: Implement thorough sanitization and validation of URL paths within the application before using them for file or resource access. Use allow-lists and deny-lists for path components.
• Path Normalization: Normalize paths to remove redundant elements like . and .. before processing in the application.
• Chroot/Jail Environments: Consider running the application in a restricted environment (chroot or jail) to limit file system access, as a defense-in-depth measure.

Attack Surface: Denial of Service (DoS) via Large Request Bodies

Description: Attackers send excessively large HTTP request bodies to exhaust server resources. fasthttp's efficiency might inadvertently lead developers to overlook request body size limits, assuming it can handle arbitrary sizes, making the application vulnerable to DoS. fasthttp Contribution: fasthttp's performance can handle many requests, but it's still susceptible to resource exhaustion from oversized bodies if limits are not explicitly set in the application or fasthttp configuration. Example: Sending a POST request with a massive Content-Length but slow data transmission. If the application attempts to buffer the entire body without limits, it can lead to memory exhaustion and server crash. Impact: Service disruption, application downtime, resource exhaustion, potential financial losses. Risk Severity: High Mitigation Strategies:

• Enforce Request Body Size Limits: Configure fasthttp's server options or implement application-level checks to enforce strict limits on the maximum allowed request body size.
• Streaming Body Handling: Process request bodies in a streaming manner instead of buffering the entire body in memory, especially for file uploads or large data submissions.
• Request Timeouts: Set appropriate timeouts for request processing in fasthttp to prevent long-running requests from consuming resources indefinitely.

Attack Surface: Connection Exhaustion/DoS

Description: Attackers open a large number of connections to the server, exceeding its capacity and preventing legitimate users from connecting. While fasthttp is designed for high concurrency, it still has limits and can be targeted by connection exhaustion attacks. fasthttp Contribution: fasthttp's ability to handle many connections can be a double-edged sword. Attackers can leverage this to attempt to exhaust the server's connection resources, even if fasthttp is more efficient than other servers. Example: A botnet opens thousands of connections and keeps them alive with minimal activity, exhausting fasthttp's connection pool and preventing new legitimate connections. Impact: Service disruption, application downtime, inability for legitimate users to access the application. Risk Severity: High Mitigation Strategies:

• Connection Limits in fasthttp: Configure fasthttp's server options to set reasonable limits on the maximum number of concurrent connections.
• Rate Limiting (Application or Proxy Level): Implement rate limiting to restrict the number of requests or connections from a single IP address or user within a timeframe, often done at the application level or using a reverse proxy in front of fasthttp.
• Connection Timeouts in fasthttp: Configure appropriate timeouts for idle connections in fasthttp to release resources held by inactive connections.
• SYN Flood Protection (Network Level): Implement SYN cookie protection or other SYN flood mitigation techniques at the network level, often outside of fasthttp itself, but crucial for overall resilience.