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Threat Model Analysis for square/workflow-kotlin

Threat: Workflow Definition Injection

  • Description: An attacker gains the ability to create or modify workflow definitions through a vulnerability that allows them to influence how workflow-kotlin loads or interprets these definitions. This is distinct from general application vulnerabilities; it focuses on the mechanism by which workflow-kotlin itself obtains the workflow structure. This could involve exploiting how the library parses configuration files, deserializes workflow data, or handles dynamically generated workflows if that generation is part of the workflow-kotlin interaction.
    • Impact:
      • Complete application compromise: The attacker can execute arbitrary code within the context of the workflow engine, leading to data exfiltration, system command execution, denial of service, or privilege escalation. This is because the workflow definition defines the actions the engine will take.
      • Bypass of security controls: The attacker can circumvent intended application logic and security checks by defining a workflow that avoids them.
    • Affected Component:
      • Workflow.render: If the rendering logic is vulnerable to injection because of how workflow-kotlin handles the input to render.
      • Workflow.sink: If the sink is used to dynamically create workflows based on untrusted input and this dynamic creation is a core part of the workflow-kotlin interaction.
      • Any custom code that is part of the workflow-kotlin integration and is responsible for loading or generating workflow definitions from external sources, specifically focusing on vulnerabilities in how workflow-kotlin processes this data.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strict Input Validation (Workflow-Specific): Implement rigorous input validation and sanitization specifically for the data used by workflow-kotlin to construct workflows. This is beyond general application input validation; it's focused on the structure and content of the workflow definition itself. Use a whitelist approach.
      • Secure Configuration Management (Workflow-Specific): If workflow definitions are loaded from files, use secure configuration management practices to prevent unauthorized modification of those files that workflow-kotlin reads.
      • Code Review (Workflow Integration Code): Thoroughly review the code that integrates with workflow-kotlin and is responsible for loading and processing workflow definitions, focusing on preventing code injection vulnerabilities in the workflow-kotlin specific parts.
      • Principle of Least Privilege (Workflow Engine): Run the workflow engine and workers with the minimum necessary privileges. This limits the damage an attacker can do even if they inject a malicious workflow.
      • Sandboxing (if applicable, within Workflow Context): If the workflow engine allows for execution of arbitrary code as part of its normal operation, consider sandboxing these executions within the workflow context.

Threat: Unexpected State Transition Exploitation (within workflow-kotlin)

  • Description: An attacker exploits a flaw in the workflow-kotlin library's state machine implementation itself or in the interaction between workflow-kotlin components to trigger an unintended state transition. This is not about logic errors in the application's workflow definition, but about bugs or vulnerabilities within workflow-kotlin's core logic. This could involve race conditions within the library, incorrect handling of edge cases in the state machine, or vulnerabilities in how workflow-kotlin manages state transitions.
    • Impact:
      • Violation of business logic: The attacker can bypass authorization checks, access restricted resources, or perform actions out of order, even if the application's workflow definition is logically sound.
      • Data corruption: The application's state may become inconsistent due to the incorrect state transition within workflow-kotlin.
      • Denial of service: The unexpected state transition could lead to an infinite loop or resource exhaustion within the workflow-kotlin engine.
    • Affected Component:
      • Workflow.render: Bugs in the rendering function within workflow-kotlin can lead to unexpected state transitions.
      • Workflow.sink: Incorrect handling of events in the sink within workflow-kotlin can trigger unintended state changes.
      • StatefulWorkflow: The core state machine implementation within workflow-kotlin.
      • Worker: If there are vulnerabilities in how workflow-kotlin interacts with workers, leading to unexpected state changes.
    • Risk Severity: High
    • Mitigation Strategies:
      • Thorough Testing (of workflow-kotlin Integration): Extensive testing of the interaction between your application and workflow-kotlin, including unit, integration, and property-based testing, to identify and eliminate logic errors and race conditions that arise from how workflow-kotlin behaves.
      • Formal Verification (of workflow-kotlin, if feasible): This is ideally done by the library maintainers, but if you have the expertise and the workflow is extremely critical, consider it.
      • Stay Up-to-Date: Keep the workflow-kotlin library up-to-date to benefit from bug fixes and security patches. This is the most important mitigation for vulnerabilities within the library.
      • Defensive Programming (within Workflow Actions): Implement checks within workflow actions to ensure preconditions and postconditions are met, even if you trust workflow-kotlin, to provide an extra layer of defense.
      • Monitoring and Auditing (of Workflow Executions): Monitor workflow executions to detect unexpected state transitions that might indicate a bug in workflow-kotlin.

Threat: Sensitive Data Leakage in Workflow Context (workflow-kotlin specific)

  • Description: Sensitive data stored in the WorkflowContext is exposed due to vulnerabilities in how workflow-kotlin handles or exposes this context. This is distinct from general application data leakage; it focuses on the WorkflowContext object and how workflow-kotlin manages it. This could be due to bugs in workflow-kotlin that cause the context to be logged inappropriately, exposed through debugging interfaces, or persisted insecurely by default.
    • Impact:
      • Data breaches: Sensitive information is exposed to unauthorized parties.
      • Compliance violations: GDPR, HIPAA, etc.
    • Affected Component:
      • WorkflowContext: The object that holds data passed between workflow steps.
      • Workflow.render: If rendering logic within workflow-kotlin exposes sensitive data from the context.
      • Any workflow-kotlin provided logging or persistence mechanisms that might handle the context insecurely.
    • Risk Severity: High
    • Mitigation Strategies:
      • Data Minimization (in Workflow Context): Store only the minimum necessary data in the WorkflowContext.
      • Encryption (of Workflow Context Data): Encrypt sensitive data stored in the WorkflowContext, both at rest and in transit, especially if using any persistence features of workflow-kotlin.
      • Review workflow-kotlin Documentation: Carefully review the workflow-kotlin documentation for any features related to context persistence, logging, or debugging, and ensure they are configured securely.
      • Access Control (to Workflow Context): Ensure that only authorized components and users can access the WorkflowContext as managed by workflow-kotlin.