threat-modeling.md

Threat Model Analysis for zeromq/libzmq

Threat: Malformed Message Handling

Threat: Malformed Message Exploitation Description: An attacker sends crafted or malformed messages to the libzmq endpoint. This could exploit vulnerabilities within libzmq itself during message processing. Attackers might trigger crashes or potentially remote code execution if libzmq's internal message handling has flaws. Impact: Application crash, denial of service, potential remote code execution, data corruption. Affected libzmq component: Message receiving and processing within libzmq sockets, internal message handling. Risk Severity: Critical Mitigation Strategies: * Regularly update libzmq to the latest version to patch potential vulnerabilities in message handling. * Consider using fuzzing techniques to test libzmq's robustness against malformed inputs (though this is more for libzmq developers). * Implement input validation at the application level before passing messages to application-specific logic, even if libzmq is expected to handle basic message structure.

Threat: Address Injection/Spoofing

Threat: Endpoint Address Spoofing (High Severity Scenario) Description: An attacker manipulates connection strings or endpoint configurations to redirect libzmq messages. They might spoof legitimate addresses to intercept communication or redirect messages to attacker-controlled endpoints. This can be achieved by modifying configuration files or through network-level attacks targeting address resolution used by libzmq. Impact: Data interception, unauthorized access, man-in-the-middle attacks, denial of service (by redirecting messages away from intended recipients). Affected libzmq component: Connection establishment, address resolution (if applicable), socket binding and connecting. Risk Severity: High Mitigation Strategies: * Implement strict validation and sanitization of all input addresses used for libzmq connections. * Use secure configuration management practices to prevent unauthorized modification of connection strings. * Employ authentication and encryption mechanisms (like CurveZMQ) to verify endpoint identities and protect communication channels, which can help mitigate address spoofing by ensuring only authenticated endpoints can connect.

Threat: Lack of Encryption by Default

Threat: Plaintext Communication Eavesdropping Description: libzmq communication, by default, is unencrypted. An attacker with network access can eavesdrop on the communication channel and intercept sensitive data transmitted between libzmq endpoints. This is a critical vulnerability when sensitive data is transmitted over untrusted networks. Impact: Confidentiality breach, exposure of sensitive data, potential compromise of application security. Affected libzmq component: Network communication layer of libzmq sockets when encryption is not explicitly enabled. Risk Severity: High Mitigation Strategies: * Mandatory Encryption: Always enable encryption for libzmq communication, especially when transmitting sensitive data or communicating over untrusted networks. * CurveZMQ: Utilize CurveZMQ's built-in encryption and authentication capabilities for secure communication.

Threat: Denial of Service (DoS) Attacks

Threat: Message Flooding DoS (High Severity Scenario) Description: An attacker floods libzmq sockets with a large volume of messages. This can overwhelm libzmq itself, leading to resource exhaustion (CPU, memory, network bandwidth) and service disruption, preventing legitimate messages from being processed by the application. Impact: Service unavailability, application performance degradation, resource exhaustion, potential system crashes. Affected libzmq component: Message queues, socket receiving and processing within libzmq. Risk Severity: High Mitigation Strategies: * Rate Limiting (at application level): Implement rate limiting on message reception to restrict the number of messages processed within a given time frame by the application. While libzmq has HWM, application level rate limiting is often more effective for DoS. * Message Queuing Limits (using libzmq HWM): Configure libzmq socket options to limit message queue sizes (ZMQ_SNDHWM, ZMQ_RCVHWM) to prevent excessive memory consumption within libzmq. * Resource Monitoring: Monitor system resources (CPU, memory, network) to detect DoS attacks early.

Threat: Man-in-the-Middle (MitM) Attacks

Threat: Communication Interception and Manipulation Description: Without encryption and endpoint verification, an attacker positioned between libzmq endpoints can intercept libzmq communication. They can eavesdrop on messages, modify them in transit, or impersonate endpoints, potentially compromising data integrity and confidentiality. Impact: Data breaches, data manipulation, unauthorized access, loss of data integrity, potential compromise of application security. Affected libzmq component: Network communication layer of libzmq sockets when encryption and authentication are not enabled. Risk Severity: High Mitigation Strategies: * Mandatory Encryption (CurveZMQ): Enforce encryption using CurveZMQ to protect communication confidentiality and integrity. * Endpoint Authentication (CurveZMQ): Utilize CurveZMQ's authentication features to verify the identity of communicating endpoints and prevent impersonation.

Threat: Memory Leaks

Threat: Resource Exhaustion due to Memory Leaks (High Severity Scenario) Description: Bugs in libzmq itself can lead to memory leaks. Over time, leaked memory accumulates within libzmq's internal structures, causing performance degradation, instability, and eventually application crashes due to memory exhaustion. Impact: Application instability, performance degradation, crashes, denial of service. Affected libzmq component: libzmq internal memory management. Risk Severity: High Mitigation Strategies: * Regular libzmq Updates: Update libzmq to the latest version, as bug fixes often include memory leak resolutions. * Memory Leak Detection Tools (for development/testing): Use memory leak detection tools (e.g., Valgrind, AddressSanitizer) during development and testing to identify potential leaks in application code and potentially uncover issues in libzmq usage patterns.

Threat: Resource Starvation due to Message Queues

Threat: Memory Exhaustion from Queue Buildup (High Severity Scenario) Description: If message processing is slow or an attacker floods the system, libzmq's internal message queues can grow excessively. This can lead to memory exhaustion within libzmq and resource starvation, impacting application performance and stability, especially in PUB/SUB patterns with slow subscribers. Impact: Application performance degradation, memory exhaustion, crashes, denial of service. Affected libzmq component: libzmq internal message queues, socket buffer management. Risk Severity: High Mitigation Strategies: * Flow Control (using libzmq HWM): Implement flow control mechanisms using libzmq socket options like ZMQ_SNDHWM and ZMQ_RCVHWM to prevent publishers from overwhelming subscribers and causing queue buildup within libzmq. * Consumer Monitoring and Scaling: Monitor consumer performance and scale consumers if necessary to keep up with message processing demand and prevent queue buildup in libzmq. * Message Dropping Policies (using libzmq options): Configure libzmq socket options to define message dropping policies when queues are full (e.g., drop oldest or newest messages) to limit memory usage within libzmq.

Threat: Incorrect Socket Options Configuration

Threat: Security Feature Bypass or Weakening (High Severity Scenario) Description: Misconfiguring libzmq socket options, either accidentally or due to misunderstanding, can disable or weaken critical security features like CurveZMQ encryption or authentication. This can directly introduce high severity vulnerabilities by negating intended security measures within libzmq. Impact: Reduced security posture, exposure to eavesdropping, unauthorized access, data breaches. Affected libzmq component: libzmq socket configuration, socket option setting API. Risk Severity: High Mitigation Strategies: * Secure Configuration Defaults: Establish secure default configurations for libzmq socket options, especially for security-sensitive options. * Configuration Validation: Implement validation checks for socket option configurations to ensure they meet security requirements, particularly for options related to encryption and authentication in libzmq. * Code Reviews: Review code that configures libzmq sockets to identify potential misconfigurations, focusing on security-related options.

Threat: Use of Deprecated or Unsafe API Features

Threat: Exploiting Known Vulnerabilities or Inefficiencies (High Severity Scenario) Description: Using deprecated or known unsafe features of the libzmq API, especially when newer and more secure alternatives exist, can introduce vulnerabilities or reduce security. Deprecated features might have known security flaws or lack modern security enhancements within libzmq itself. Impact: Security vulnerabilities, reduced security posture, potential exploitation of known weaknesses in libzmq. Affected libzmq component: libzmq API usage in application code, specifically deprecated or unsafe API functions. Risk Severity: High Mitigation Strategies: * Use Latest Recommended API: Always use the latest recommended and secure libzmq API features. * Avoid Deprecated Features: Avoid using deprecated API features and migrate to recommended alternatives. * libzmq Documentation Review: Regularly review libzmq documentation for API changes and security recommendations to ensure usage of current best practices.

Threat: Outdated libzmq Version

Threat: Exploiting Known libzmq Vulnerabilities Description: Using an outdated version of libzmq that contains known security vulnerabilities. Security vulnerabilities are often discovered and patched in newer versions of libzmq. Using an old version leaves the application directly vulnerable to these known issues within libzmq, which attackers may actively exploit. Impact: Security vulnerabilities, potential remote code execution, data breaches, denial of service, depending on the specific libzmq vulnerability. Affected libzmq component: Entire libzmq library, specifically vulnerable components in the outdated version. Risk Severity: Critical Mitigation Strategies: * Regular libzmq Updates: Keep libzmq updated to the latest stable version to benefit from security patches and bug fixes. * Vulnerability Monitoring: Monitor security advisories and vulnerability databases for known vulnerabilities in libzmq versions to prioritize updates.