Jenkins – Security Best Practices

Pre-requisite: Jenkins

Jenkins is an open-source automation server that offers hundreds of plugins to help you build, deploy, and automate your projects. It is commonly used in continuous integration and continuous delivery (CI/CD) to automate the software delivery process. Jenkins runs on various platforms such as Windows, Linux, and macOS and supports various programming languages ​​such as Java, .NET, and Python.

Jenkins provides a web interface for configuring and managing your builds and a range of tools and features for managing your software development lifecycle. B. Source control, build triggers, build pipelines, and integration with other tools and systems.

Methods for securing Jenkins

Here are some methods and ways to be followed to ensure security while using Jenkins :

Hardening of the OS

Here are some best practices for hardening the operating system (OS) in a Jenkins setup:

• Use a secure and supported operating systems, such as Ubuntu LTS or Red Hat Enterprise Linux.
• Keep the operating system and all its components up-to-date with the latest security patches.
• Use strong passwords and regularly rotate the credentials for all privileged accounts, such as the root account.
• Configure firewalls to limit access to the Jenkins server from the public internet.
• Disable or remove any unnecessary services, ports, and protocols that are not needed for Jenkins.
• Implement intrusion detection and prevention systems (IDS/IPS) to monitor network traffic for malicious activity.
• Enable and configure auditing to log system events, such as logins, file access, and system configuration changes.
• Use access control mechanisms such as SELinux or AppArmor to enforce security policies and limit the damage that can be done by a compromised process.
• Use encryption to protect sensitive data, such as by using encrypted file systems or disk encryption.
• Conduct regular security assessments and penetration testing to identify vulnerabilities in your operating system and network setup.

Authorization

Authorization in Jenkins refers to the process of controlling access to resources and operations within Jenkins, such as jobs, build history, artifacts, and other configuration settings.

Here are some best practices for authorization in Jenkins:

• Implement role-based access control (RBAC) to define different roles and permissions within Jenkins.
• Use LDAP or Active Directory to manage user authentication and authorization centrally.
• Configure project-based authorization to restrict access to specific jobs, build artifacts, and other resources.
• Use matrix-based authorization to control access to resources and operations based on combinations of user and group permissions.
• Use security realms to integrate Jenkins with external authentication systems, such as GitHub or Google.
• Enable secure authentication for Jenkins’ web interface, such as using HTTPS or SSL certificates.
• Use the Role Strategy Plugin to implement custom authorization strategies, such as allowing only specific users to execute shell scripts in Jenkins jobs.
• Regularly review and audit the authorization settings to ensure that they meet your organization’s security policies.
• Provide training and education to Jenkins users on the importance of proper authorization and secure password practices.
• Regularly monitor logs and audit trails for unauthorized access attempts and take appropriate action to prevent future incidents.

Security (Mis)Configurations

Here are some common security misconfigurations in Jenkins that can compromise the security of a Jenkins setup:

• Lack of Secure Authentication: Using simple or easily guessable passwords, or not enabling secure authentication mechanisms such as LDAP or Active Directory.
• Unrestricted Access to the Jenkins Master: Allowing unrestricted access to the Jenkins master, such as from the public internet, or not limiting access to trusted individuals.
• Unsecured Communication: Not using encrypted protocols, such as HTTPS, to secure communication between Jenkins and other tools.
• Inadequate Backups: Not regularly backing up Jenkins data, or not having a disaster recovery plan in place in case of data loss or system failure.
• Unsecured Credentials Storage: Storing sensitive information, such as passwords and private keys, in clear text or using insecure methods to store and manage credentials.
• Use of Unverified Scripts: Allowing the execution of unverified scripts, or not using code signing to verify the authenticity of scripts before executing them.
• Lack of Security Monitoring: Not regularly monitoring the logs and audit trails, or not having adequate security alerts and notifications in place to detect potential security incidents.
• Use of Deprecated or Vulnerable Plugins: Using outdated or vulnerable plugins, or not keeping Jenkins and its plugins up-to-date with the latest versions.
• Lack of Secure Network Configuration: Not properly configuring firewalls, or not using intrusion detection and prevention systems to monitor network traffic for malicious activity.
• Lack of Secure OS Configuration: Not properly hardening the operating system, or not using encryption to protect sensitive data.

It is important to regularly review and audit the security configuration of Jenkins to prevent these security misconfigurations and ensure the security of your Jenkins setup.

Authentication

Authentication in Jenkins refers to verifying a user’s or system’s identity before allowing access to Jenkins resources and operations.

Here are some best practices for authentication in Jenkins:

• Enable secure authentication for the Jenkins web interface, such as using HTTPS or SSL certificates.
• Use strong and unique passwords for all Jenkins user accounts, and regularly rotate these passwords.
• Use a centralized authentication system, such as LDAP or Active Directory, to manage user authentication and authorization.
• Integrate Jenkins with external authentication systems, such as GitHub or Google, to allow users to log in using their existing accounts.
• Use two-factor authentication (2FA) to add an additional layer of security to the authentication process.
• Regularly monitor and audit authentication logs to detect and prevent unauthorized access attempts.
• Provide training and education to Jenkins users on the importance of secure password practices.
• Regularly review and audit the authentication settings to ensure that they meet your organization’s security policies.
• Use the Role-Based Authentication Plugin to implement custom authentication strategies, such as allowing only specific users to execute shell scripts in Jenkins jobs.
• Implement security measures to prevent brute-force attacks and password guessing, such as rate limiting and IP blocking.

Making Strong Inbound Connections

Here are some best practices for making strong inbound connections in Jenkins:

• Use encrypted protocols, such as HTTPS, to secure communication between Jenkins and other tools.
• Implement firewalls and access controls to restrict incoming connections to only trusted sources.
• Use intrusion detection and prevention systems to monitor network traffic for malicious activity.
• Configure secure authentication for incoming connections, such as using SSL/TLS certificates or secure authentication mechanisms such as LDAP or Active Directory.
• Regularly monitor and audit incoming connections to detect and prevent unauthorized access attempts.
• Implement rate limiting to prevent brute-force attacks and denial-of-service (DoS) attacks.
• Use security groups and network segmentation to isolate sensitive systems and data from the public internet.
• Regularly review and audit the inbound connection settings to ensure that they meet your organization’s security policies.
• Use VPNs or other secure remote access solutions to allow remote users to securely connect to Jenkins.
• Implement network monitoring and logging to detect and respond to security incidents, and to assist with post-incident analysis.

Disabling Executors on the Controller Node

Disabling executors on the Jenkins controller node means preventing Jenkins jobs from being executed on the master node. This can be done to reduce the security risk associated with managing jobs on the same node as the Jenkins management interface.

Here are the steps to disable executors on the controller node in Jenkins:

1. Log in to the Jenkins web interface.
2. Navigate to “Manage Jenkins” > “Configure System”.
3. Scroll down to the “Master Node” section.
4. Uncheck the “Launch agent via Java Web Start” checkbox.
5. Save the changes.

After completing these steps, jobs will no longer be executed on the Jenkins master node. Instead, they will be executed on Jenkins agents, which can be deployed on separate nodes. This can help to reduce the risk associated with executing jobs on the same node as the Jenkins management interface, as well as provide better scalability and performance for larger Jenkins setups.

Disabling SSHD

Disabling SSHD in Jenkins refers to disabling the Secure Shell (SSH) service on the Jenkins master node. This is a security measure to prevent unauthorized access to the Jenkins server through the SSH protocol.

Here are the steps to disable SSHD in Jenkins:

1. Log in to the Jenkins master node as an administrator.
2. Open the SSH configuration file, typically located at /etc/ssh/sshd_config.
3. Look for the “Port” directive and comment it out by adding a # symbol in front of it.
4. Save the changes and close the file.
5. Restart the SSH service by executing the following command: sudo systemctl restart ssh
6. Verify that the SSH service is no longer listening on the network by executing the following command: sudo ss -ltp | grep ssh

After completing these steps, the Jenkins master node will no longer accept incoming SSH connections. This can help to prevent unauthorized access to the Jenkins server through the SSH protocol, and can also reduce the attack surface of the Jenkins system. However, it may also prevent authorized users from accessing the Jenkins server through the SSH protocol, so be sure to consider the impact on your workflows before disabling SSHD in Jenkins.

Agent Permissions Set to Limit 

Setting agent permissions in Jenkins is a way to control the level of access that agents have to the Jenkins server and resources. Limiting agent permissions can help to reduce the security risk associated with running jobs on agents, especially if the agents are managed by third-party entities or are running untrusted code.

Here are the steps to set agent permissions to a limit in Jenkins:

1. Log in to the Jenkins web interface.
2. Navigate to “Manage Jenkins” > “Manage Nodes”.
3. Select the agent for which you want to set permissions.
4. Click on the “Agent” section, then the “Advanced” button.
5. Enter the desired agent permissions in the “Agent launch command” field, such as “JENKINS_AGENT_NAME=agent java -jar agent.jar -workDir /tmp/agent”.
6. Save the changes.

By setting agent permissions in this way, you can limit the access that agents have to the Jenkins server and resources. For example, you can restrict the agents to only be able to write to specific directories, or only be able to run specific commands. This can help to reduce the security risk associated with running jobs on agents, and can also help to enforce compliance with security policies and standards.

Securing the Credentials

Securing the credentials in Jenkins is an integral part of ensuring the security and privacy of your systems and data. Here are some best practices for securing the credentials in Jenkins:

• Use the Jenkins Credentials Plugin to store sensitive information such as passwords, API keys, and SSH keys.
• Implement the least privilege principle and restrict access to credentials to only those who need it.
• Encrypt sensitive information in transit and at rest using SSL/TLS or equivalent encryption mechanisms.
• Use strong, unique passwords and rotate them regularly.
• Regularly audit the credentials and remove any unused or unnecessary credentials.
• Use two-factor authentication (2FA) to provide an extra layer of security.
• Enable access logging to monitor and detect any unauthorized access attempts.
• Implement a disaster recovery plan to restore credentials in case of a security breach or other disaster.
• Regularly review and audit your credential security practices to ensure that they meet your organization’s security policies.

By following these best practices, you can help to secure the credentials in Jenkins and protect your systems and data from unauthorized access and breaches.

Audit Logs

Audit logs in Jenkins are records of events and actions that occur within the Jenkins system, such as job builds, user logins, and configuration changes. Audit logs can provide valuable information for troubleshooting, security investigations, and compliance reporting.

Here are some best practices for using audit logs in Jenkins:

• Enable audit logging in Jenkins by going to “Manage Jenkins” > “System Log”.
• Configure the log rotation policy to ensure that logs are stored for a sufficient amount of time to meet your organization’s requirements.
• Use a centralized log management system to store and manage audit logs from all Jenkins nodes in a single location.
• Regularly review audit logs to detect and respond to security incidents, such as unauthorized access attempts, and to monitor system activity.
• Use automated log analysis tools to detect anomalies and suspicious activity in the audit logs.
• Ensure that audit logs are protected against tampering and unauthorized access.
• Implement a disaster recovery plan for the audit logs to ensure that they can be recovered in case of a security breach or other disaster.

By following these best practices, you can effectively use audit logs in Jenkins to support security investigations, troubleshooting, and compliance reporting. This can help to improve the security and reliability of your Jenkins system and to protect your systems and data from unauthorized access and breaches.

Conclusion

In conclusion, securing Jenkins is crucial for ensuring the security and privacy of your systems and data. There are various best practices that can be implemented to secure Jenkins, including hardening the operating system, setting up proper authorization and authentication, securing sensitive information such as credentials, and implementing an effective audit logging mechanism.

By following these best practices, you can help to reduce the security risks associated with using Jenkins and protect your systems and data from unauthorized access and breaches. Regularly reviewing and auditing your security practices can also help to ensure that they remain effective over time and continue to meet your organization’s security policies and standards.