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Exposing a Critical Security flaw in Jenkins Application

Exposing security flaw in Jenkins application

In the ever-evolving world of cybersecurity, vigilance and continuous improvement are paramount. Recently, I stumbled upon a significant security flaw in a Jenkins application. This vulnerability arose from leaked credentials, allowed unauthorized access to a trove of sensitive information, and could allow potential multiple account takeovers. This blog aims to detail the discovery process, the implications of the breach, and best practices to mitigate such risks.

Discovery Process

  1. Initial Encounter with Leaked Credentials: The journey began with a casual search that led me to a public data leak on the dark net containing what appeared to be sensitive information. Among various files, one particularly clear text credential caught my attention as the same credential can be used for multiple internal applications. A clear text credential leak for one of the employees of the client. It was related to the Jenkins public application.
    Leaked Credentials in Jenkins Application
  2. Accessing Jenkins Web Application: Armed with the leaked credentials, I accessed the Jenkins web application. To my astonishment, the login was successful, granting me normal user privileges. Unfortunately, we were not able to access the /script endpoint which can lead to remote code execution. Hence, we looked for other information that could be obtained from the source code and other build history.Accessing Jenkins Web Application
  3. Exploring Jenkins for Sensitive Information: Navigating through the Jenkins dashboard, I systematically explored the various projects and configurations. Jenkins, being a continuous integration and continuous deployment (CI/CD) tool, often stores critical information for seamless operations. Here’s a breakdown of the sensitive data I retrieved.
    • Database Credentials: Plain text credentials for the company’s production database.
    • Code Access: Access to the 650+ code repositories along with git access.
    • API Keys: Access tokens for various third-party services.
    • JWT Secrets: Secrets used for signing and verifying JSON Web Tokens.
    • Environment Variables: Configurations for different deployment environments, including URLs and admin credentials.

Implications of the Breach

The potential damage from this security flaw in the Jenkins application cannot be overstated. Unauthorized access to such sensitive information could lead to:

  • Data Breach: Exposure of sensitive customer and corporate data.
  • Service Disruption: Malicious actors could alter configurations, leading to downtime or degraded service quality.
  • Financial Loss: Exploitation of API keys and database credentials could result in significant financial repercussions.
  • Reputation Damage: Public knowledge of such a breach could severely tarnish the company’s reputation.

Technical Breakdown of the Security Flaw in Jenkins Application

  • Understanding Jenkins Configuration: Jenkins configurations are often stored in XML or other configuration files within the Jenkins home directory. Key files of interest include:
    • config.xml
    • Job-specific configuration files (e.g., job/confcig.xml)
  • Credentials Storage: Jenkins encrypts stored credentials, but improper handling or leaked configuration files can expose these secrets. In this case, the credentials were found in a publicly accessible repository.
  • Accessing and Extracting Data: Using the administrative access granted by the leaked credentials, I was able to navigate to the Manage Jenkins section. From there, accessing Manage Credentials revealed the plaintext secrets stored within various credentials domains.

Mitigation Strategies

Credential Hygiene:

  • Avoid Hard-Coding Credentials: Use environment variables or secret management tools such as HashiCorp Vault, AWS Secrets Manager, or Azure Key Vault to securely store and handle sensitive information.
  • Regular Rotation: Regularly rotate credentials and keys to minimize the impact of potential leaks. Automated tools and scripts can facilitate this process.

Secure Jenkins Configuration:

  • Access Control: Implement robust access controls and follow the principle of least privilege. Ensure that only authorized personnel have access to critical configurations and credentials.
  • Audit and Monitoring: Regularly audit Jenkins configurations and monitor access logs for unusual activity. Integrate tools like Splunk or ELK stack for comprehensive monitoring and alerting.

Repository Management:

  • Private Repositories: Ensure you store sensitive configuration files and credentials in private repositories with restricted access.
  • Code Scanning: Utilize automated tools like GitGuardian, TruffleHog, or SonarQube to scan repositories for leaked secrets and sensitive information before committing code.

Continuous Security Practices:

  • Security Training: Regularly train developers and DevOps teams on secure coding practices and the importance of securing CI/CD pipelines.
  • Patch Management: Keep Jenkins and all plugins up to date with the latest security patches and updates to mitigate vulnerabilities.

Incident Response Plan:

  • Preparedness: Firstly, develop and maintain an incident response plan that includes steps to take in the event of a security breach. Secondly, regularly test and update the plan.
  • Containment and Recovery: Ensure quick containment and recovery procedures are in place to minimize damage and restore normal operations as swiftly as possible.

Multi-Factor Authentication (MFA):

  • Enhanced Security: Implement multi-factor authentication (MFA) for accessing Jenkins and other critical systems to add an extra layer of security beyond just passwords.

By adopting these mitigation strategies, organizations can significantly enhance their security posture, protect sensitive information, and ensure the integrity of their CI/CD pipelines.

This article was written by Keyur Talati, Sr. Security Analyst at FireCompass.