OVH Bastion: Prevent Gatekeepers From Self-Adding

Hello everyone! This article addresses a common concern among OVH Bastion users: how to prevent gatekeepers from adding themselves to groups they manage. We'll explore the current capabilities of OVH Bastion, discuss potential solutions, and delve into the possibility of future feature enhancements.

The Challenge: Gatekeepers and Self-Addition

In many organizations, OVH Bastion plays a crucial role in securing access to critical infrastructure. Bastion servers act as a single point of entry, controlling and auditing connections to internal resources. A key aspect of managing Bastion environments is the concept of gatekeepers – users who are authorized to manage group memberships. However, a potential issue arises when gatekeepers have the ability to add themselves to groups, which can lead to unintended privilege escalation or security vulnerabilities. Preventing this self-addition is the core of our discussion. Let’s dive deeper into understanding this issue.

When we talk about security within an infrastructure, especially one managed through a system like OVH Bastion, the principle of least privilege is paramount. This principle dictates that users should only have the necessary permissions to perform their job duties, and nothing more. The concern around gatekeepers adding themselves directly contravenes this core concept. A gatekeeper, by virtue of their role, is trusted to manage group memberships and ensure the right individuals have access to the right resources. But allowing a gatekeeper to self-assign access can bypass the checks and balances that are put in place to maintain security integrity. This action can occur either maliciously or unintentionally, but in either scenario, the implications can range from minor inconvenience to a significant security breach. For example, a gatekeeper might inadvertently grant themselves elevated privileges, leading to misconfiguration or unauthorized access to sensitive data. Alternatively, in a malicious scenario, a compromised gatekeeper account could be exploited to gain broader access to the system, making it imperative to implement controls that restrict this behavior. The design and implementation of an access control system must inherently consider these potential risks and incorporate mechanisms to mitigate them, fostering a secure and trustworthy environment for all stakeholders involved.

Current OVH Bastion Capabilities

As of version 3.22.00, the OVH Bastion documentation and community forums don't explicitly offer a built-in feature to prevent gatekeepers from adding themselves. This means that, by default, if a user has gatekeeper privileges for a group, they can modify the membership, including adding their own account. This behavior isn't necessarily a flaw, but it highlights the need for careful consideration of user roles and permissions within your Bastion setup. Understanding the current OVH Bastion capabilities is vital for making informed decisions about security configurations.

Delving into the technical aspects, most bastion systems, including OVH Bastion, operate on a role-based access control (RBAC) model. In RBAC, permissions are associated with roles, and users are assigned to these roles. Gatekeepers are essentially users who are assigned a role with the permission to manage group memberships. The system checks whether a user has the gatekeeper role when they attempt to add or remove members. However, the default implementation often doesn't differentiate between adding others and adding oneself. This is where the challenge lies. The system sees the gatekeeper as authorized to modify the group and doesn't impose a restriction on who the gatekeeper can add, which includes their own user account. To change this behavior, one might need to implement additional layers of control or customizations, which can range from modifying the application's code to integrating with external policy enforcement systems. It’s also crucial to consider the audit trails that the bastion system provides. A robust audit trail can help detect instances where a gatekeeper has added themselves, even if preventive measures are not in place. Regularly reviewing these audit logs is a best practice for ensuring that access controls are being adhered to and for identifying any potential misuse or misconfigurations.

Potential Solutions and Workarounds

While a direct setting to disable self-addition may not exist, several potential solutions and workarounds can be implemented. These approaches range from access control adjustments to custom scripting and external policy enforcement.

One straightforward approach is to carefully review and adjust the access control policies within OVH Bastion. This might involve creating more granular roles and permissions, limiting the scope of gatekeeper privileges. For instance, instead of granting a single