Tenable Nessus Agent Operational Tier (Tenable Vulnerability Management)

The primary purpose for the Operational Tier (Tenable Vulnerability Management) was to perform agent management and agent scan operations.

Functions performed

The following processes and uses take place in the Operational Tier (Tenable Vulnerability Management).

• Deployed agents are linked to Tenable Vulnerability Management.
• Agents are organized in agent groups. Agents can be assigned to agent groups during the installation process.
• Agent scans are established to obtain assessment results from agents via agent groups.
• Agents automatically have plugin and version updates applied by Tenable Vulnerability Management.
• Customers can “opt out” of having agent version updates automatically applied.

Considerations

• Agents were deployed using ACME's internal software distribution processes (in this case, SCCM).
• Agent groups included no more than 20,000 agents per group (10,000 is recommended). Limiting the number of agents in each agent group ensures that Tenable Security Center can import scan results successfully. This limitation only applies when Tenable Security Center is part of the deployment.
• Agent scans were restricted to a single agent group each.
• Agent group membership was established by functional zones (by location, role, etc.) for organizational purposes.
• ACME monitored for agent deployment issues (failed installations, linking failures, etc.) out of band (logging client, scripts, etc.).
• Agents only performed local vulnerability assessments and did not perform network-based assessment (for example, SSL or CGI network-based assessments).
• Network and firewalls were configured to allow agents to communicate with https://cloud.tenable.com.

Tier design

Design assumptions included:

• ACME leverages internal processes and tooling to deploy the Tenable Nessus Agent software.
• ACME establishes 50-70 agent groups.
• ACME configures 50-70 agent scans.