threat-modeling.md

Threat Model Analysis for app-vnext/polly

Threat: Overly Aggressive Retry Policy Exploitation

Description: An attacker might intentionally cause service degradation to trigger overly aggressive retry policies configured in Polly. This can amplify a minor issue into a self-inflicted Denial of Service (DoS) as the application overwhelms backend services with excessive retry requests. - Impact: Service unavailability, performance degradation, cascading failures, resource exhaustion on backend systems. - Polly Component Affected: RetryPolicy, PolicyBuilder (configuration) - Risk Severity: High - Mitigation Strategies: - Implement exponential backoff and jitter in retry policies. - Set reasonable limits on the number of retries. - Monitor backend service health and dynamically adjust retry policies. - Implement circuit breaker patterns to prevent retry storms.

Threat: Infinite Retry Loop Trigger

Description: An attacker might craft requests or manipulate system state to create conditions that trigger an infinite retry loop within a misconfigured Polly retry policy. This can lead to excessive consumption of server resources (CPU, memory, network), causing application instability, crash, or a DoS. - Impact: Application crash, service unavailability, resource exhaustion, potential server compromise due to resource starvation. - Polly Component Affected: RetryPolicy, PolicyBuilder (configuration), ExecuteAndCapture function - Risk Severity: High - Mitigation Strategies: - Ensure retry policies have clear exit conditions (max retries, specific exception types to stop retrying). - Use circuit breakers to break out of potential infinite loops. - Thoroughly test retry policies under failure scenarios. - Implement timeouts to prevent indefinite waiting within retry loops.

Threat: Retry Storm Amplification

Description: In distributed systems, if an attacker causes a service outage, the coordinated retry attempts from multiple application instances using Polly can create a "retry storm." This storm can overwhelm the recovering service, preventing it from becoming healthy and prolonging the outage, effectively amplifying the initial attack's impact. - Impact: Prolonged service outage, cascading failures, prevention of service recovery, amplified impact of initial attack. - Polly Component Affected: RetryPolicy, PolicyBuilder (configuration), distributed application deployments using Polly - Risk Severity: High - Mitigation Strategies: - Implement jitter in retry policies to desynchronize retry attempts. - Use circuit breakers to prevent retries when a service is unavailable. - Implement exponential backoff to reduce retry frequency over time. - Consider centralized retry management in large distributed systems.

Threat: Security Bypass via Overly Permissive Policies

Description: An attacker might exploit overly permissive Polly policies that retry or fallback even on security-related failures (e.g., authentication failures, authorization failures). If Polly policies are configured to retry or fallback on these failures, it could unintentionally bypass intended security checks, allowing unauthorized access or actions. - Impact: Security bypass, unauthorized access, data breaches, compromise of application integrity. - Polly Component Affected: RetryPolicy, FallbackPolicy, PolicyBuilder (configuration), exception handling logic within policies. - Risk Severity: High - Mitigation Strategies: - Carefully define which exceptions should trigger resilience policies and which should be treated as definitive security failures. - Ensure security-related failures (e.g., 401, 403) are not bypassed by retry or fallback unless explicitly intended and thoroughly reviewed for security implications. - Design policies to differentiate between transient errors and persistent security failures. - Implement specific exception filters in policies to prevent retries or fallbacks for security-related exceptions.

Threat: Dependency Vulnerability Exploitation

Description: An attacker could exploit known security vulnerabilities present in the Polly library itself or its underlying dependencies if outdated versions are used. Exploiting these vulnerabilities could lead to severe consequences, including remote code execution, complete system compromise, or significant data breaches. - Impact: Application compromise, remote code execution, DoS, data breaches, loss of confidentiality, integrity, and availability. - Polly Component Affected: Polly library itself, dependent libraries (transitive dependencies). - Risk Severity: Critical - Mitigation Strategies: - Keep Polly and all its dependencies up to date with the latest stable versions and security patches. - Regularly monitor security advisories and vulnerability databases for Polly and its dependencies. - Utilize dependency scanning tools to automatically identify known vulnerabilities in project dependencies. - Implement a robust process for promptly patching or upgrading dependencies when security vulnerabilities are discovered.