When you deploy Web Agent, familiarize yourself with the recommendations for the host operating systems that you use. For comprehensive information about securing operating systems, see the CIS Benchmark documentation.
Over the lifetime of a deployment, the operating system might be subject to vulnerabilities. Some vulnerabilities require system upgrades, whereas others require only configuration changes. All updates require proactive planning and careful testing.
For the operating systems used in production, put a plan in place for avoiding and resolving security issues. The plan should answer the following questions:
How does your organization become aware of system security issues early?
This could involve following bug reports, mailing lists, forums, and other sources of information.
How do you test security fixes, including configuration changes, patches, service packs, and system updates?
Validate the changes first in development, then in one or more test environments, then in production in the same way you would validate other changes to the deployment.
How do you roll out solutions for security issues?
In some cases, fixes might involve both changes to the service, and specific actions by those who use the service.
What must you communicate about security issues?
How must you respond to security issues?
Software providers often do not communicate what they know about a vulnerability until they have a way to mitigate or fix the problem. Once they do communicate about security issues, the information is likely to become public knowledge quickly. Make sure that you can expedite resolution of security issues.
To resolve security issues quickly, make sure that you are ready to validate any changes that must be made. When you validate a change, check that the fix resolves the security issue. Validate that the system and Web Agent software continue to function as expected in all the ways they are used.
System audit logs make it possible to uncover system-level security policy violations that are not recorded in Web Agent, such as unauthorized access to Web Agent files. Such violations are not recorded in Web Agent logs or monitoring information.
Also consider how to prevent or at least detect tampering. A malicious user violating security policy is likely to try to remove evidence of how security was compromised.
By default, operating systems include many features, accounts, and services that Web Agent software does not require. Each optional feature, account, and service on the system brings a risk of additional vulnerabilities. To reduce the surface of attack, enable only required features, system accounts, and services. Disable or remove those that are not needed for the deployment.
The features needed to run and manage Web Agent software securely include the following:
Software to secure access to service management tools; in particular, when administrators access the system remotely.
Software to secure access for remote transfer of software updates, backup files, and log files.
Software to manage system-level authentication, authorization, and accounts.
Firewall software, intrusion-detection/intrusion-prevention software.
Software to allow auditing access to the system.
System update software to allow updates that you have validated previously.
If required for the deployment, system access management software such as SELinux.
Any other software that is clearly indispensable to the deployment.
Consider the minimal installation options for your operating system, and the options to turn off features.
Consider configuration options for system hardening to further limit access even to required services.
For each account used to run a necessary service, limit the access granted to the account to what is required. This reduces the risk that a vulnerability in access to one account affects multiple services across the system.
Make sure that you validate the operating system behavior every time you deploy new or changed software. When preparing the deployment and when testing changes, maintain a full operating system with Web Agent software that is not used for any publicly available services, but only for troubleshooting problems that might stem from the system being too minimally configured.