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Threat Model Analysis for collectiveidea/delayed_job

Threat: Arbitrary Code Execution (ACE) via Deserialization

  • Description: An attacker crafts malicious input that, when deserialized by delayed_job's worker, executes arbitrary code on the server. The attacker leverages vulnerabilities in how delayed_job handles the deserialization of job arguments, often exploiting weaknesses in serialization libraries like YAML or Marshal, or in the application's handling of the deserialized objects. The attacker might submit a specially crafted object that, upon deserialization, triggers unintended code execution.
    • Impact: Complete system compromise. The attacker gains full control over the server running the delayed_job worker, allowing them to steal data, install malware, or use the server for other malicious purposes.
    • Affected Component:
      • Delayed::Job.enqueue (and related methods like delay): The entry point where job data is serialized.
      • Delayed::Worker: The process that deserializes and executes jobs.
      • The underlying serialization library used by delayed_job (e.g., YAML, Marshal, or a custom serializer).
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strongly Prefer JSON: Use JSON as the serialization format. It's significantly less prone to deserialization vulnerabilities.
      • Whitelist Serializers (if not using JSON): If you must use another serializer, use ActiveJob::Serializers::ObjectSerializer with a strict whitelist of allowed classes. Never allow arbitrary classes to be deserialized.
      • Input Validation: Rigorously validate and sanitize all data before it's passed as arguments to delayed_job. Never trust user-supplied data directly.
      • Regular Updates: Keep delayed_job, the Ruby runtime, and all related gems (especially serialization libraries) up-to-date to patch known vulnerabilities.
      • Least Privilege: Run worker processes with the minimum necessary permissions.

Threat: Data Leakage via Job Arguments

  • Description: An attacker gains access to the database or queue backend and reads the arguments of enqueued or completed jobs. Because delayed_job stores job arguments in the database (by default), this could expose sensitive information like passwords, API keys, or PII that were mistakenly passed as job arguments. An attacker might also exploit logging vulnerabilities where delayed_job or the application inadvertently logs these arguments.
    • Impact: Data breach, potentially leading to identity theft, financial loss, or reputational damage. The severity depends on the sensitivity of the leaked data.
    • Affected Component:
      • Delayed::Job (the database table): Stores the serialized job data, including arguments.
      • Application logs (if delayed_job or application code logs arguments).
    • Risk Severity: High
    • Mitigation Strategies:
      • Avoid Sensitive Arguments: Never pass sensitive data directly as job arguments. Instead, pass identifiers (e.g., user IDs) and retrieve the sensitive data within the job's execution context from a secure store.
      • Database Encryption: Encrypt the handler column (or equivalent) in the delayed_jobs table if sensitive data must be stored.
      • Secure Logging: Implement robust logging practices that never log raw job arguments. Sanitize logs and error messages. Ensure delayed_job's logging is configured securely.
      • Database Access Control: Strictly limit access to the delayed_jobs table.

Threat: Denial of Service (DoS) via Job Overload

  • Description: An attacker submits a large number of jobs to delayed_job, overwhelming the worker processes and preventing legitimate jobs from being processed. This exploits delayed_job's queuing mechanism. The attacker might submit jobs that are designed to consume excessive resources or take a very long time, further exacerbating the DoS.
    • Impact: Service disruption. Legitimate users are unable to use the application's features that rely on delayed_job.
    • Affected Component:
      • Delayed::Worker: The processes that execute jobs.
      • Delayed::Job.enqueue (and related methods): The entry point for adding jobs to the queue.
    • Risk Severity: High
    • Mitigation Strategies:
      • Rate Limiting: Implement rate limiting on job enqueuing, limiting the number of jobs a single user or IP address can submit within a given time period. This directly mitigates the attack vector.
      • Job Prioritization: Implement job priorities to ensure critical jobs are processed first.
      • Queue Monitoring: Monitor queue length and worker resource usage. Alert on unusual spikes.
      • Job Timeouts: Implement timeouts for jobs. If a job takes too long, terminate it.
      • Resource Limits: Set resource limits (CPU, memory) for worker processes.
      • Separate Worker Pools: Use separate worker pools for resource-intensive jobs.

Threat: Job Poisoning

  • Description: An attacker submits a job to delayed_job that appears legitimate but contains malicious code within the job's logic itself. This is distinct from deserialization attacks; the vulnerability lies within the application's custom job code, which delayed_job executes. The attacker exploits a vulnerability in how the job handles its arguments or interacts with other system components.
    • Impact: Varies widely depending on the malicious code, but can include data corruption, unauthorized access, or even complete system compromise.
    • Affected Component:
      • The custom code within the job class that delayed_job executes (e.g., the perform method).
    • Risk Severity: High
    • Mitigation Strategies:
      • Secure Coding Practices: Thoroughly review and test all job code for security vulnerabilities. Treat job code with the same level of scrutiny as any other application code.
      • Input Validation (Within the Job): Even if job arguments are validated before enqueuing, perform additional validation and sanitization within the job's code that delayed_job runs.
      • Avoid Dangerous Functions: Avoid using eval, system, or other potentially dangerous functions within job code that delayed_job will execute.
      • Regular Security Audits: Perform regular security audits and penetration testing, specifically targeting the job processing components executed by delayed_job.