Attack Surface: 1. Unprotected Process Engine API (REST/Java)
Description: Exposure of the Camunda engine's core API endpoints without proper authentication and authorization. This is a fundamental part of how Camunda operates.
Camunda Contribution: Camunda provides these APIs as the primary means of interacting with the engine. Their existence and functionality are inherent to the platform.
Example: An attacker uses the publicly accessible REST API (/engine-rest/process-instance) to start hundreds of instances of a resource-intensive process, causing a denial-of-service. Or, they modify process variables containing sensitive data.
Impact: Denial of service, unauthorized data access/modification, unauthorized process execution, complete system compromise (if the attacker can then deploy malicious models).
Risk Severity: Critical
Mitigation Strategies:
* Authentication: Implement strong authentication (OAuth 2.0, JWT, Basic Auth with robust password policies, API keys). This is mandatory.
* Authorization: Use Camunda's built-in authorization service (or a custom implementation, but Camunda's is recommended) to enforce fine-grained access control. Grant only the minimum necessary permissions.
* Network Segmentation: Isolate the Camunda engine from untrusted networks. Use a firewall.
* API Rate Limiting: Implement rate limiting to prevent abuse.
* Input Validation: While Camunda does some internal validation, validate all input you send to the API to prevent unexpected behavior.
* Regular Auditing: Monitor API access logs.
Attack Surface: 2. Malicious Process Definition Deployment
Description: Deployment of BPMN, DMN, or CMMN models containing malicious code or configurations through Camunda's deployment mechanisms. Camunda Contribution: Camunda's core function is to execute these process definitions. The deployment mechanism is a built-in, essential feature. Example: An attacker deploys a BPMN model via the REST API with a script task that executes arbitrary shell commands, gaining system access. Impact: Arbitrary code execution, data exfiltration, system compromise, denial of service. Risk Severity: Critical Mitigation Strategies: * Secure Deployment Endpoints: Protect the deployment API (REST/Java) with strong authentication and authorization (as with the general engine API). * Model Validation: Implement strict server-side validation of deployed models before Camunda processes them. Use a whitelist of allowed elements, attributes, scripts, and expressions. This is crucial; don't rely on client-side checks. * Sandboxed Scripting: Configure Camunda to use a secure scripting engine with sandboxing capabilities. This limits the damage a malicious script can do. * Disable Auto-Deployment: Disable auto-deployment from the classpath in production. * Deployment Pipeline: Use a dedicated deployment pipeline with automated security checks integrated with Camunda's deployment process.
Description: Injection of malicious code into script tasks that Camunda is responsible for executing. Camunda Contribution: Camunda provides the scripting engine and executes the scripts within its context. The vulnerability arises from how Camunda handles and executes these scripts. Example: A process variable containing unsanitized user input is directly used within a JavaScript script task that Camunda executes. The attacker provides malicious JavaScript. Impact: Arbitrary code execution (within the Camunda engine's context), data exfiltration, potential for system compromise. Risk Severity: High Mitigation Strategies: * Input Sanitization: Sanitize all data used in script tasks, even if it comes from other parts of the process. Treat all process variables as potentially tainted. * Sandboxed Scripting: Use a secure, sandboxed scripting engine (configure this within Camunda). * External Scripts: Avoid inline scripts. Store scripts externally and reference them. This makes auditing and control easier. * Principle of Least Privilege: Configure the Camunda engine (and its scripting engine) to run with the minimum necessary privileges. * Code Review (of process definitions): Review process definitions for how they use scripts.
Attack Surface: 4. Expression Language Injection (within Camunda's evaluation)
Description: Injection of malicious code into expressions that Camunda evaluates. Camunda Contribution: Camunda uses and evaluates these expressions as part of its core functionality. Example: A condition in a gateway uses an expression evaluating unsanitized user input. The attacker provides a malicious expression. Impact: Data exfiltration, potential for limited code execution (depending on the expression language and context), unauthorized access to process data. Risk Severity: High Mitigation Strategies: * Input Sanitization: Sanitize all data used in expressions, treating process variables as potentially tainted. * Parameterized Expressions: Use parameterized expressions where possible (this is often supported by the expression language). * Avoid Dynamic Expressions: Minimize dynamic expressions based on untrusted input. * Contextual Output Encoding: If expressions must include potentially tainted data, ensure proper contextual output encoding is used by the expression evaluator (this is a Camunda configuration concern).