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  • Writer's pictureDemetrios Mustakas Jr.

Quick Wins: Securing VMware vCenter Server

What are "Quick Wins"?

Concise articles offer actionable insights, time-saving tips, or effective strategies to address practical challenges in securing your virtualized environment.

Just the facts

It is important to secure the vCenter Server Appliance (vCSA). As the central management component of vSphere, vCenter Server requires careful attention to security measures. This article provides a summary overview of best practices and considerations for securing vCenter Server. We will touch on various aspects, including vCenter authentication, role-based access controls (RBAC), vCenter High Availability (HA), protection of vCenter databases, and ensuring secure backups and disaster recovery.

Securing vCenter Authentication

Securing the authentication process is fundamental to maintaining the integrity of vCenter Server. There are several considerations with regards to authentication (and identity management).

  1. Begin with Strong Passwords - Configure the password policy for any account used in the Single Sign-On (SSO) default domain for the vCenter server to have a minimum number of characters (the default is 8, I recommend 12 or more) which include both upper and lower case letters, numbers, and special characters. The longer and more complex (i.e. stronger) a password is, the less often it may be necessary to change it (default for vCenter is 90 days).

  2. Consider implementing identity federation using an external authentication source - Beginning with vSphere 7, multi-factor authentication (MFA) is available when using a supported external identity provider. This is a change from the prior method of simply connecting to an LDAP or Integrated Windows authentication.

  3. Use SSL/TLS 1.2 for encrypting data transmission between vCenter and component clients - in prior version of vSphere TLS 1.0/1.1 was supported and configurable. Beginning with the most recent version of vSphere 6.7 TLS 1.2 was supported, but not required. vSphere 8 no longer supports TLS 1.0/1.1 with TLS 1.2 enabled by default.

Implementing Role-Based Access Controls (RBAC)

RBAC is crucial for controlling access and privileges within vCenter Server. Regular review and updates of RBAC configurations are highlighted to align with organizational changes and maintain a secure environment.

  1. Establish a principle of least privilege. This is a security concept that involves granting users or entities only the minimum privileges or permissions necessary to perform their assigned tasks or functions. It aims to limit potential damage or unauthorized actions by restricting access to sensitive resources or system functionalities.

  2. Create separation of duties. This involves distributing tasks and responsibilities among individuals to reduce a risk of fraud, errors, or unauthorized activities. It avoids allowing a single individual or entity complete control over key operations, increasing accountability while mitigating potential risks.

  3. Configure granular access controls. Define fine-grained permissions and restrictions for accessing and managing resources. Specifically assigning permissions to roles for later assignment to accounts.

Enabling vCenter High Availability (HA)

High Availability ensures uninterrupted access to vCenter Server, even in the face of hardware failures or system outages. There are several benefits and considerations of enabling vCenter HA and ensure a resilient and highly available vCenter environment.

  1. Dependency planning - Ensure that the vCenter Server is installed on a supported version and that the environment meets the necessary requirements. Prior to configuring vCenter High Availability (VCHA), it is essential to verify the availability of adequate memory, CPU, and datastore resources. Additionally, ensure that both your vCenter Server and ESXi versions are compatible and support the vCenter HA feature.

  2. Cluster configurations - Consider the availability and capacity requirements of the environment when determining the number of hosts in the cluster. A vCenter High Availability (VCHA) cluster comprises three vCenter Server instances, serving specific roles within the cluster. Initially, the first instance operates as the Active node. To create redundancy, it is cloned to form a Passive node and a Witness node. This arrangement establishes an active-passive failover solution where the nodes work together to ensure continuous availability of vCenter Server services.

  3. Network redundancy - vCenter HA network latency between Active, Passive, and Witness nodes must be less than 10 ms. The vCenter HA network must be on a different subnet than the management network. Ensure redundant and highly available network connectivity for VCSA nodes.

  4. Failover testing - Regularly perform failover tests to validate the effectiveness of VCHA and ensure proper failover and failback procedures. Simulate different failure scenarios to assess the resilience and recoverability of your vCenter Server environment.

  5. Monitoring and alerting - Configure monitoring for the health of the vCenter HA state, PSC HA state, Cluster status for the VCHA failover nodes, data base replication events and appliance file replicate events.

Protecting vCenter Databases

The vCenter Server database contains critical information about the virtual infrastructure, making its protection crucial

  1. Strong database passwords - This may seem redundant given that "strong passwords" is often mentioned in security literature. Attackers are targeting the vCenter server database password in order to compromise and then extract additional key information such as the vpxuser password, allowing for root level access to ESXi hosts.

  2. Restrict access - limit access to the vCenter Server to only authorized personnel. Implement strict access control to accomplish this. Regularly review and audit user rights as well as access alerts to vCenter.

  3. Backup the database - Perform regular backups of the database and store them securely in an offsite location or on separate storage media. Test the database backup and restore procedures periodically to verify their effectiveness and reliability.

Ensuring Secure Backups and Disaster Recovery

Backups and disaster recovery are vital components of a comprehensive security strategy. This section focuses on securing vCenter Server backups, including considerations for secure backup storage, encryption of backup data, and off-site replication for disaster recovery purposes. Testing backup and recovery processes is emphasized to ensure their reliability during critical situations.

  1. Secure backup storage - Ensure vCenter Server backups are stored on dedicated and secure storage systems or devices to prevent unauthorized access. Establish physical and logical isolation of the backup storage from the production environment, minimizing the risk of data breaches. Implement stringent access controls and authentication mechanisms, allowing only authorized personnel to access and manage the backup storage.

  2. Encrypt backup data - Enable encryption for vCenter Server backups to protect sensitive data from unauthorized disclosure or tampering. Utilize robust encryption algorithms and protocols to ensure the confidentiality and integrity of the backup data. Safeguard encryption keys and certificates used for backup encryption to prevent unauthorized access and maintain the security of the encrypted backups.

  3. Off-site Replication for Disaster Recover - Replicate vCenter Server backups to off-site locations or secondary data centers to ensure a reliable disaster recovery solution. Implement secure data replication mechanisms that provide encryption and authentication for the transfer of backup data to protect it during transit. Regularly test and validate the off-site replication process to verify its effectiveness and reliability, ensuring the availability of backups for disaster recovery scenarios.

Wrap up

Securing VMware vCenter Server requires a comprehensive approach that addresses various aspects of its operation. By following the best practices and considerations outlined in this article, organizations can significantly enhance the security of their vCenter environments. Emphasizing secure authentication, implementing RBAC, enabling vCenter HA, protecting databases, and ensuring secure backups and disaster recovery will bolster the integrity, availability, and confidentiality of vCenter Server deployments. Proactive monitoring, regular updates, and adherence to VMware's security recommendations are vital to maintaining a secure vCenter environment. Safeguard your vCenter Server and fortify your virtual infrastructure against evolving threats, ensuring the continuity of your critical operations.


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