Objective: Achieve RCE on Flink Cluster
[[Attacker Goal: Achieve RCE on Flink Cluster]] | | [[1. Exploit Flink Job Submission/Management]] | ----------------------------------- | | [[1.1 Malicious Job]] [1.2 API Abuse] | |
| | | [A] [B] [D]
Attack Tree Path: Attacker Goal: Achieve RCE on Flink Cluster
- Description: The ultimate objective of the attacker is to gain Remote Code Execution (RCE) on the Flink cluster. This allows the attacker to execute arbitrary code, potentially leading to data exfiltration, denial of service, or lateral movement within the network. This is the root of the entire attack tree.
- Criticality: This is the most critical node as it represents the attacker's final objective.
Attack Tree Path: 1. Exploit Flink Job Submission/Management
- Description: This node represents the primary attack surface for compromising a Flink cluster. Flink's core functionality revolves around accepting and running jobs, making this a prime target for attackers. Attackers can exploit vulnerabilities in how jobs are submitted, validated, and managed to achieve their goals.
- Criticality: This is a critical node because it's the gateway to most high-risk attack paths. Securing this aspect of Flink is paramount.
Attack Tree Path: 1.1 Malicious Job
- Description: This node focuses on the attacker submitting a crafted Flink job that contains malicious code or exploits vulnerabilities in the job execution process. This is a direct way to achieve RCE.
- Criticality: This is a critical node because it represents the most direct and often the most straightforward method for an attacker to gain RCE.
Attack Tree Path: 1.1 -> [A] Job Code Injection (Deserialization)
- Description: Flink uses serialization (e.g., Java serialization, Kryo, Avro) to transfer job code and data. If the application improperly handles user-supplied data during deserialization, an attacker can inject malicious objects. When these objects are deserialized, they execute arbitrary code. This leverages the well-known dangers of insecure deserialization.
- Likelihood: Medium to High (depending on serialization method and input validation).
- Impact: Very High (RCE, complete system compromise).
- Effort: Medium (Requires crafting a malicious payload; tools like ysoserial can assist).
- Skill Level: Intermediate to Advanced (Understanding of Java serialization vulnerabilities and exploit development).
- Detection Difficulty: Medium to Hard (Requires monitoring for unusual class loading, process behavior, or using specialized security tools).
- Mitigation:
- Strictly validate and sanitize all user-supplied data before deserialization.
- Prefer safer serialization formats (Avro, Protobuf) with well-defined schemas over Java serialization.
- Implement a whitelist of allowed classes for deserialization, if possible.
- Use a security manager to restrict the permissions of deserialized code.
- Monitor for unusual class loading activity.
- Consider using tools like ysoserial (for testing) and contrast security (for runtime protection).
Attack Tree Path: 1.1 -> [B] Malicious JAR Upload
- Description: If the Flink UI or API allows uploading JAR files without proper validation, an attacker can upload a JAR containing malicious code disguised as a legitimate Flink job. When the job is executed, the malicious code runs.
- Likelihood: Medium (Depends on the presence and security of upload functionality).
- Impact: Very High (RCE, complete system compromise).
- Effort: Low (If upload is permitted; crafting a malicious JAR is relatively easy).
- Skill Level: Intermediate (Basic Java development skills).
- Detection Difficulty: Medium (Requires file integrity monitoring, malware scanning, and potentially static analysis of uploaded JARs).
- Mitigation:
- Implement strict validation of uploaded JAR files.
- Check file signatures.
- Scan for malware.
- Restrict the execution environment of submitted jobs (e.g., using containers with limited privileges).
- Limit who can upload JARs to trusted users/roles.
- Consider using a static analysis tool to inspect the JAR's bytecode for suspicious patterns.
Attack Tree Path: 1.2 -> [D] Insufficient Authentication/Authorization
- Description: If the Flink REST API or other management interfaces are not properly secured with authentication and authorization, an attacker can interact with the cluster without proper credentials. This allows them to submit jobs, cancel jobs, access sensitive information, or even modify the cluster's configuration.
- Likelihood: Medium (If security is not properly configured).
- Impact: High to Very High (Unauthorized job submission, data access, cluster control, potential for RCE).
- Effort: Low (If authentication is weak or absent; basic HTTP requests are sufficient).
- Skill Level: Novice to Intermediate (Basic understanding of HTTP requests and API interaction).
- Detection Difficulty: Easy to Medium (Requires monitoring API access logs for unauthorized requests and unusual activity).
- Mitigation:
- Enable authentication and authorization for the Flink REST API and all management interfaces.
- Use strong passwords or, preferably, token-based authentication (e.g., Kerberos, OAuth 2.0).
- Implement role-based access control (RBAC) to restrict API access based on user roles.
- Regularly audit API access logs.
- Use API gateways for additional security and control.