How to Reduce Cyber Risk with Tenable Hexa AI and Agentic Defense

As threat actors increasingly leverage Artificial Intelligence to accelerate their attacks—from discovering vulnerabilities to exfiltrating data—security teams face a critical challenge. Traditional, reactive security operations are no longer sufficient to keep pace. To defend against AI-enabled adversaries, organizations must adopt AI-driven defense mechanisms.

The recent announcement of Tenable Hexa AI marks a significant shift in exposure management. By acting as an agentic AI engine within the Tenable One platform, it empowers defenders to automate complex workflows, drastically reducing operational workloads and transforming raw exposure data into coordinated, protective action. This post explores how this technology works and how your organization can leverage it to stay ahead of modern threats.

Executive Takeaways

• Shift from Reactive to Preemptive: Agentic AI allows security teams to move beyond constant "firefighting" by automating the identification and prioritization of risks.
• Operational Efficiency: By orchestrating actions across humans and automation, Hexa AI reduces the "alert fatigue" that burdens modern Security Operations Centers (SOCs).
• Unified Defense: The integration of AI with an Exposure Data Fabric provides a holistic view of the attack surface, enabling better-informed defensive decisions.

Technical Analysis

Tenable Hexa AI is not merely a generative AI chatbot; it is an agentic engine designed to perform autonomous tasks. It is built upon the Tenable One Exposure Management Platform and utilizes the underlying Exposure Data Fabric to ingest and normalize vast amounts of security data across cloud, identity, and on-premises assets.

Core Capabilities:

1. Autonomous Orchestration: Hexa AI utilizes "agents" to interact with other systems and humans. It can trigger specific security actions, such as creating a ticket in a ServiceNow instance or initiating a vulnerability scan, without manual intervention.
2. Workflow Automation: It bridges the gap between detection and remediation. Instead of simply flagging a critical vulnerability, Hexa AI can contextualize the risk—considering threat intelligence and asset criticality—and prescribe a specific remediation plan.
3. Exposure Intelligence Transformation: The engine queries the Exposure Data Fabric to answer complex questions about the security posture, converting that data into actionable intelligence for defenders.

Strategic Importance: For defenders, the primary value proposition is speed and accuracy. Attackers using AI can find and exploit vulnerabilities in hours. Tenable Hexa AI counters this by shrinking the "time-to-remediate" window, allowing security teams to identify and mitigate exposures before they can be weaponized.

Defensive Monitoring

While implementing AI-driven platforms like Tenable One is crucial, organizations must also maintain robust detection capabilities to identify tools and behaviors associated with exposure discovery and potential attacker reconnaissance. The following detection rules and queries help ensure that your environment is monitored for both external scanning and the proper deployment of your defensive agents.

SIGMA Detection Rules

These rules help detect unauthorized network scanning (which exposes vulnerabilities) and verify the deployment of security agents that feed your exposure management platform.

---
title: Execution of Network Scanning Tool Nmap
id: 4a8d7b4a-2e1c-4f9d-8a5e-6b4c3d2e1f0a
status: experimental
description: Detects the execution of the Nmap network scanning tool, which is often used by attackers to discover exposed services and vulnerabilities.
references:
  - https://attack.mitre.org/techniques/T1595/
author: Security Arsenal
date: 2025/04/15
tags:
  - attack.discovery
  - attack.t1595.001
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|contains: 'nmap.exe'
    or
    OriginalFileName|contains: 'nmap.exe'
falsepositives:
  - Authorized security penetration testing
level: high
---
title: Tenable Nessus Agent Installation or Update
id: b7c8d9e0-f1a2-3456-bcde-f01234567890
status: experimental
description: Detects the installation or update of the Tenable Nessus Agent, ensuring coverage for exposure management platforms.
references:
  - https://docs.tenable.com/nessus/
author: Security Arsenal
date: 2025/04/15
tags:
  - attack.execution
  - attack.t1059.001
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith: '\NessusAgent.exe'
    CommandLine|contains:
      - '/install'
      - '/update'
falsepositives:
  - Legitimate administrator or software management system installing the agent
level: low

KQL (Microsoft Sentinel/Defender)

Use these queries to hunt for scanning activity or verify agent status across your fleet.

// Detect Nmap or similar scanning tool execution
DeviceProcessEvents
| where Timestamp > ago(1d)
| where FileName in~ ("nmap.exe", "masscan.exe", "netcat.exe")
   or ProcessVersionInfoOriginalFileName in~ ("nmap.exe", "masscan.exe")
| project Timestamp, DeviceName, InitiatingProcessAccountName, FolderPath, FileName
| order by Timestamp desc


// Verify Tenable Nessus Agent Service Status (requires specific connector or logs)
// Assuming DeviceRegistryEvents or similar for service installation
DeviceRegistryEvents
| where Timestamp > ago(7d)
| where RegistryKey contains "NessusAgent"
| project Timestamp, DeviceName, RegistryKey, RegistryValueName, RegistryValueData, ActionType
| order by Timestamp desc

Velociraptor VQL

Hunt for potentially unwanted scanning tools on Linux or Windows endpoints to identify rogue exposure discovery activities.

-- Hunt for common network scanning tools on Linux/Unix endpoints
SELECT Name, Path, Size, Mode, Mtime
FROM glob(globs='/usr/bin/*', root=/)
WHERE Name IN ('nmap', 'masscan', 'netcat', 'nc')
   AND Mode =~ 'x'

-- Hunt for Nmap on Windows endpoints
SELECT FullPath, Size, Mtime
FROM glob(globs='C:\**\nmap.exe')

PowerShell Verification Script

Use this script to audit the presence and running state of the Tenable Nessus Agent on Windows endpoints, which is required for data ingestion into the Exposure Data Fabric.

<#
.SYNOPSIS
    Check Tenable Nessus Agent Status.
.DESCRIPTION
    Verifies if the Tenable Nessus Agent service is installed and running.
#>

$serviceName = "Tenable Nessus Agent"
$service = Get-Service -Name $serviceName -ErrorAction SilentlyContinue

if ($service) {
    $status = $service.Status
    $startType = $service.StartType
    
    if ($status -eq 'Running') {
        Write-Host "[+] SUCCESS: $serviceName is currently $status (StartType: $startType)." -ForegroundColor Green
    } else {
        Write-Host "[-] WARNING: $serviceName is installed but not running. Current status: $status" -ForegroundColor Yellow
    }
} else {
    Write-Host "[-] ERROR: $serviceName is not installed on this system." -ForegroundColor Red
}

Remediation

To effectively implement a defensive strategy utilizing Agentic AI like Tenable Hexa AI, organizations should take the following steps:

1. Ensure Complete Asset Visibility: Deploy the Tenable Nessus Agent or enable scanners across all critical assets, including cloud workloads, containers, and identity providers. Without data, the AI engine cannot function.

2. Integrate with ITSM Tools: Configure Tenable One to integrate with your IT Service Management (e.g., ServiceNow, Jira) solutions. This allows Hexa AI to automatically create and update tickets, closing the loop on remediation.

3. Define Risk Acceptance Policies: Clearly define risk thresholds within the platform. This guides the AI in prioritizing which exposures require immediate automated action and which need human review.

4. Automate Patching Workflows: Where possible, link the exposure intelligence to patch management tools (e.g., SCCM, Intune) to enable fully automated patching for high-priority, low-complexity vulnerabilities.

5. Monitor Agent Health: Use the provided PowerShell scripts and monitoring rules to ensure that agents remain active and reporting. If an agent stops reporting, that asset becomes a blind spot for your AI defense.

By adopting these measures, security teams can leverage Tenable Hexa AI to transition from a reactive posture to a preemptive defense model, effectively reducing cyber risk in an era of accelerated threats.

Related Resources

Security Arsenal Alert Triage Automation AlertMonitor Platform Book a SOC Assessment platform Intel Hub