attack-surface.md

Attack Surface Analysis for gorilla/websocket

Attack Surface: Cross-Site WebSocket Hijacking (CSWSH)

Description: An attacker on a malicious website tricks a user's browser into initiating a websocket connection to a legitimate server on the attacker's behalf, potentially gaining unauthorized access.

• Websocket Contribution: Websockets, if not properly secured, are vulnerable to cross-site request forgery-like attacks due to their persistent connection nature and reliance on origin-based access control which can be bypassed if not strictly implemented.
• Example: A user is logged into a sensitive application (e.g., trading platform) in one browser tab. In another tab, they visit a malicious website. This website's JavaScript initiates a websocket connection to the trading platform's websocket endpoint. If the platform lacks robust origin validation and session binding for websockets, the malicious website might be able to execute trades or access account information as the logged-in user.
• Impact: Unauthorized access to sensitive websocket functionality, financial loss (in trading scenarios), data theft, ability to perform critical actions on behalf of the victim user, complete account takeover.
• Risk Severity: Critical
• Mitigation Strategies:
  • Strict Origin Validation: Implement rigorous Origin header validation on the server-side, using a whitelist and rejecting any requests with unexpected or missing origins.
  • Synchronizer Tokens (CSRF Tokens) for Websockets: Integrate CSRF protection mechanisms specifically for websocket connections. This involves issuing a unique, unpredictable token to the client (e.g., via HTTP cookie during initial page load) and requiring the client to present this token during the websocket handshake or initial message exchange for validation.
  • Session Binding and Verification: Strongly bind websocket connections to authenticated user sessions. Verify session validity not only during the initial handshake but also periodically throughout the websocket connection lifecycle. Ensure session invalidation on logout also terminates associated websocket connections.

Attack Surface: Message Injection and Manipulation

Description: Attackers send crafted websocket messages to exploit vulnerabilities in the server's message processing logic, inject malicious payloads, or manipulate application state in unintended ways.

• Websocket Contribution: Websockets provide a direct, bidirectional communication channel. If the server-side application doesn't rigorously validate and sanitize incoming messages, this channel becomes a prime vector for injecting malicious data or commands.
• Example: A real-time gaming application uses websockets for game commands. If the server directly processes commands from websocket messages without validation, an attacker could send a crafted message like {"command": "grant_admin_privileges", "player_id": "attacker"}. Another critical example is exploiting deserialization flaws by sending malicious JSON or other serialized data within websocket messages, leading to remote code execution.
• Impact: Remote code execution on the server, critical data corruption or loss, complete application logic bypass, privilege escalation to administrative levels, denial of service through resource exhaustion or crashes.
• Risk Severity: Critical
• Mitigation Strategies:
  • Comprehensive Input Validation and Sanitization: Implement robust input validation and sanitization for all data received via websocket messages on the server-side. Enforce strict data type and format checks. Use allow-lists for expected values and reject anything outside of these lists.
  • Secure Message Parsing and Deserialization: Use well-vetted and regularly updated libraries for parsing message formats (e.g., JSON, Protocol Buffers). Be extremely cautious with deserialization, as it is a common source of vulnerabilities. Avoid deserializing untrusted data directly into complex objects if possible.
  • Principle of Least Privilege in Message Handling: Design the websocket message processing logic with the principle of least privilege. Minimize the permissions of the code handling websocket messages. Avoid directly executing commands or modifying critical system state based on websocket input without multiple layers of validation and authorization.
  • Content Security Policy (CSP) as Defense-in-Depth: While CSP is primarily HTTP-focused, it can offer a layer of defense if message injection vulnerabilities lead to reflected cross-site scripting (XSS) in the web application UI that interacts with the websocket.

Attack Surface: Denial of Service (DoS) via Message Flooding

Description: Attackers flood the websocket server with a massive volume of messages, overwhelming server resources and causing service disruption or complete outage for legitimate users.

• Websocket Contribution: The persistent and real-time nature of websocket connections, combined with the potential for high message frequency, makes them an effective vector for DoS attacks if proper rate limiting and resource management are not in place.
• Example: An attacker establishes numerous websocket connections and sends an overwhelming number of messages per second to the server. If the server lacks rate limiting or message queue management, it will become overloaded trying to process these messages, leading to CPU exhaustion, memory depletion, and ultimately service unavailability for legitimate clients.
• Impact: Complete service disruption, inability for legitimate users to access the application, significant financial losses due to downtime, reputational damage.
• Risk Severity: High
• Mitigation Strategies:
  • Aggressive Rate Limiting: Implement strict rate limiting on websocket message reception. Limit the number of messages allowed per connection and per IP address within short time intervals. Employ adaptive rate limiting that can dynamically adjust based on traffic patterns.
  • Message Queueing and Throttling: Use message queues to buffer incoming websocket messages and process them at a controlled rate. Implement throttling mechanisms to drop or delay excess messages during periods of high load.
  • Connection Limits and Concurrency Control: Limit the maximum number of concurrent websocket connections from a single IP address and globally. Implement robust connection management to efficiently handle and reject excessive connection attempts.
  • Resource Monitoring and Auto-Scaling: Continuously monitor server resource utilization (CPU, memory, network bandwidth, connection count). Implement automated scaling mechanisms to dynamically increase server capacity in response to increased load or attack attempts.

Attack Surface: Session Management Vulnerabilities (Websocket Context) leading to Hijacking

Description: Weak or flawed session management for websocket connections can allow attackers to hijack legitimate user sessions and gain unauthorized access to the websocket communication stream, potentially leading to account compromise.

• Websocket Contribution: Websockets often operate within the context of authenticated user sessions established via HTTP. If the session binding between HTTP and websocket is weak or session identifiers are predictable or insecurely managed, session hijacking becomes a critical risk.
• Example: An application uses easily guessable or predictable session IDs for websocket connections. An attacker could brute-force or guess valid session IDs and then initiate a websocket connection using a hijacked session ID. If the server insufficiently validates the session, the attacker gains access to the websocket communication intended for the legitimate user. Failure to invalidate websocket sessions upon user logout is another critical session management flaw.
• Impact: Complete session hijacking, unauthorized access to all websocket communication and potentially associated user data, impersonation of legitimate users, ability to perform actions as the hijacked user, account takeover.
• Risk Severity: Critical
• Mitigation Strategies:
  • Cryptographically Secure Session ID Generation: Use cryptographically strong, unpredictable, and sufficiently long session IDs. Avoid sequential or easily guessable session identifiers.
  • Secure Session Storage and Handling: Store session information securely server-side. Protect session IDs during transmission (HTTPS for initial handshake).
  • Robust Session Invalidation: Implement proper session invalidation mechanisms. When a user logs out, explicitly invalidate both the HTTP session and any associated websocket sessions. Implement session timeouts to automatically expire inactive sessions.
  • Session Renewal/Rotation for Websockets: Consider session renewal or rotation specifically for websocket sessions to limit the lifespan of session identifiers and reduce the window of opportunity for hijacking.
  • Strong Binding between HTTP Session and Websocket: Establish a strong and verifiable link between the initial HTTP authenticated session and the subsequent websocket connection. Verify this link throughout the websocket connection lifecycle.

Attack Surface: Handshake Manipulation for Bypassing Security Controls

Description: Attackers manipulate the websocket handshake process to bypass security measures, negotiate unintended protocol parameters, or downgrade to less secure protocols.

• Websocket Contribution: The websocket handshake is the initial negotiation phase. Weaknesses in handshake validation or acceptance criteria can undermine subsequent security measures and allow attackers to establish connections with weakened security or bypass intended access controls.
• Example: An attacker modifies the Sec-WebSocket-Protocol header in their handshake request to force the server to use a less secure or vulnerable subprotocol than intended. Or, they might attempt to manipulate the Origin header in conjunction with other handshake parameters to bypass origin-based access control checks that are not implemented robustly.
• Impact: Bypassing intended authentication or authorization mechanisms, forcing protocol downgrade attacks to weaker or vulnerable protocols, enabling vulnerable or unintended websocket extensions, unauthorized access to websocket functionality.
• Risk Severity: High
• Mitigation Strategies:
  • Strict Handshake Validation: Implement rigorous server-side validation of all handshake headers, including Origin, Sec-WebSocket-Protocol, and Sec-WebSocket-Extensions.
  • Whitelist Approved Protocols and Extensions: Explicitly whitelist and only accept secure and approved websocket subprotocols and extensions. Reject any handshake requests proposing unapproved or less secure options.
  • Secure Protocol Negotiation Logic: Carefully design and implement the protocol negotiation logic. Avoid relying solely on client-provided preferences. Enforce server-side preferences for security and protocol versions.
  • Connection Source Verification Beyond Origin: For highly sensitive applications, consider supplementing Origin header validation with additional connection source verification techniques, such as requiring pre-established authenticated HTTP sessions or using unique, server-generated tokens during the handshake process to verify the legitimacy of the connection source.

Attack Surface: Data Leakage of Sensitive Information via Websocket Messages

Description: Unintentional or negligent disclosure of sensitive information through websocket messages, either during normal operation, in error conditions, or through verbose logging.

• Websocket Contribution: Websockets provide a persistent, bidirectional communication channel that can be easily monitored or intercepted if not properly secured. Developers must be extremely cautious about the data transmitted over this channel, especially sensitive information.
• Example: An application sends detailed debug logs or verbose error messages over websocket connections, inadvertently revealing internal system paths, database query details, or even snippets of sensitive data to connected clients. Another example is broadcasting private user data (e.g., personal details, financial information) to all connected clients in a group chat application instead of only to authorized recipients.
• Impact: Exposure of sensitive Personally Identifiable Information (PII), financial data, or confidential business information, leading to privacy violations, regulatory non-compliance, reputational damage, and potential for further targeted attacks based on leaked information.
• Risk Severity: High
• Mitigation Strategies:
  • Minimize Data Transmission: Only transmit absolutely necessary data over websocket connections. Avoid sending sensitive information unless strictly required and protected with strong encryption.
  • Secure Error Handling and Logging: Implement secure error handling that prevents the disclosure of sensitive internal details in error messages sent over websockets. Log detailed errors server-side in secure logs, but send only generic, non-revealing error responses to clients via websockets.
  • Strict Access Control and Authorization for Data Transmission: Implement robust access control and authorization mechanisms to ensure that users only receive data they are explicitly authorized to access. Validate data access permissions before sending any data over websockets.
  • Data Encryption for Sensitive Information: Encrypt sensitive data before transmitting it over websocket connections. Use strong encryption algorithms and secure key management practices. Consider end-to-end encryption where feasible for maximum confidentiality.
  • Regular Security Audits and Code Reviews: Conduct regular security audits and code reviews specifically focused on websocket communication to identify and remediate potential data leakage vulnerabilities.