Building Vulnerability Scanning Workflow

Building Vulnerability Scanning Workflow

When to Use

Use this skill when:

• SOC teams need to establish or improve recurring vulnerability scanning programs
• Scan results require prioritization beyond raw CVSS scores using asset context and threat intelligence
• Vulnerability data must be integrated into SIEM for correlation with exploitation attempts
• Remediation tracking needs formalization with SLA-based dashboards and reporting

Do not use for penetration testing or active exploitation — vulnerability scanning identifies weaknesses, penetration testing validates exploitability.

Common Misconfigurations & Verification

• Uncredentialed scan reports a false clean: the #1 failure is a scan policy missing or misconfigured credentials — Nessus/Qualys then sees only network-facing banners and reports a fraction of real findings, making a badly-patched host look healthy. Confirm authentication succeeded per host (Nessus plugin 19506 "Scan Information" / 21745 auth-failure, Qualys authentication status) before trusting "no criticals."
• SIEM correlation join never matches: the exploitation-detection SPL builds vuln_key = Host.":".CVE and joins to IDS dest_ip.":".cve_id. If Nessus emits hostnames while IDS logs IPs, or one side lacks a CVE (multi-CVE plugins put CVEs in a multivalue field), the join yields nothing and you miss active exploitation. Normalize host→IP and mvexpand the CVE field, then test against a known event.
• KEV/asset lookups silently empty: lookup cisa_kev_lookup.csv and asset_criticality_lookup.csv return null if the CSV is stale or the key case/format differs (CVE-2024-0001 vs lowercase), so KEV criticals never alert and everything defaults to low priority. Refresh the KEV feed on a schedule and verify a known KEV CVE resolves.
• Risk math / ticket flood: risk_score >= 8.0 ticketing without dedup opens a new ServiceNow incident every scan cycle for the same unpatched host — dedup on host+CVE and update existing tickets.
• Verification: seed a deliberately vulnerable test host (e.g., known-unpatched VM), run the full pipeline, and confirm the finding appears with correct CVSS, KEV flag, SLA, and a single ticket; reconcile scan coverage count against asset inventory to catch unreachable segments.

Prerequisites

• Vulnerability scanner (Tenable Nessus Professional, Qualys VMDR, or OpenVAS/Greenbone)
• Asset inventory with criticality classifications (business-critical, standard, development)
• Network access from scanner to all target segments (agent-based or network scan)
• SIEM integration for scan result ingestion and correlation
• Patch management system (WSUS, SCCM, Intune) for remediation tracking

Workflow

Step 1: Define Scan Scope and Scheduling

Create scan policies covering all asset types:

Nessus Scan Configuration (API):

import requests

nessus_url = "https://nessus.company.com:8834"
headers = {"X-ApiKeys": f"accessKey={access_key};secretKey={secret_key}"}

# Create scan policy
policy = {
    "uuid": "advanced",
    "settings": {
        "name": "SOC Weekly Infrastructure Scan",
        "description": "Weekly credentialed scan of all server and workstation segments",
        "scanner_id": 1,
        "policy_id": 0,
        "text_targets": "10.0.0.0/16, 172.16.0.0/12",
        "launch": "WEEKLY",
        "starttime": "20240315T020000",
        "rrules": "FREQ=WEEKLY;INTERVAL=1;BYDAY=SA",
        "enabled": True
    },
    "credentials": {
        "add": {
            "Host": {
                "Windows": [{
                    "domain": "company.local",
                    "username": "nessus_svc",
                    "password": "SCAN_SERVICE_PASSWORD",
                    "auth_method": "Password"
                }],
                "SSH": [{
                    "username": "nessus_svc",
                    "private_key": "/path/to/nessus_key",
                    "auth_method": "public key"
                }]
            }
        }
    }
}

response = requests.post(f"{nessus_url}/scans", headers=headers, json=policy,
                         verify=not os.environ.get("SKIP_TLS_VERIFY", "").lower() == "true")  # Set SKIP_TLS_VERIFY=true for self-signed certs in lab environments
scan_id = response.json()["scan"]["id"]
print(f"Scan created: ID {scan_id}")

Qualys VMDR Scan via API:

import qualysapi

conn = qualysapi.connect(
    hostname="qualysapi.qualys.com",
    username="api_user",
    password="API_PASSWORD"
)

# Launch vulnerability scan
params = {
    "action": "launch",
    "scan_title": "Weekly_Infrastructure_Scan",
    "ip": "10.0.0.0/16",
    "option_id": "123456",  # Scan profile ID
    "iscanner_name": "Internal_Scanner_01",
    "priority": "0"
}

response = conn.request("/api/2.0/fo/scan/", params)
print(f"Scan launched: {response}")

Step 2: Process and Prioritize Scan Results

Download results and apply risk-based prioritization:

import requests
import csv

# Export Nessus results
response = requests.get(
    f"{nessus_url}/scans/{scan_id}/export",
    headers=headers,
    params={"format": "csv"},
    verify=not os.environ.get("SKIP_TLS_VERIFY", "").lower() == "true",  # Set SKIP_TLS_VERIFY=true for self-signed certs in lab environments
)

# Parse and prioritize
vulns = []
reader = csv.DictReader(response.text.splitlines())
for row in reader:
    cvss = float(row.get("CVSS v3.0 Base Score", 0))
    asset_criticality = get_asset_criticality(row["Host"])  # From asset inventory

    # Risk-based priority calculation
    risk_score = cvss * asset_criticality_multiplier(asset_criticality)

    # Boost score if actively exploited (check CISA KEV)
    if row.get("CVE") in cisa_kev_list:
        risk_score *= 1.5

    vulns.append({
        "host": row["Host"],
        "plugin_name": row["Name"],
        "severity": row["Risk"],
        "cvss": cvss,
        "cve": row.get("CVE", "N/A"),
        "risk_score": round(risk_score, 1),
        "asset_criticality": asset_criticality,
        "kev": row.get("CVE") in cisa_kev_list
    })

# Sort by risk score
vulns.sort(key=lambda x: x["risk_score"], reverse=True)

CISA KEV (Known Exploited Vulnerabilities) Check:

import requests

kev_response = requests.get(
    "https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json"
)
kev_data = kev_response.json()
cisa_kev_list = {v["cveID"] for v in kev_data["vulnerabilities"]}

# Check if vulnerability is actively exploited
def is_actively_exploited(cve_id):
    return cve_id in cisa_kev_list

Step 3: Define Remediation SLAs

Apply SLA-based remediation timelines:

Step 4: Integrate with SIEM for Exploitation Detection

Correlate vulnerability scan data with SIEM alerts to detect active exploitation:

index=vulnerability sourcetype="nessus:scan"
| eval vuln_key = Host.":".CVE
| join vuln_key type=left [
    search index=ids_ips sourcetype="snort" OR sourcetype="suricata"
    | eval vuln_key = dest_ip.":".cve_id
    | stats count AS exploit_attempts, latest(_time) AS last_exploit_attempt by vuln_key
  ]
| where isnotnull(exploit_attempts)
| eval risk = "CRITICAL — Vulnerability being actively exploited"
| sort - exploit_attempts
| table Host, CVE, plugin_name, cvss_score, exploit_attempts, last_exploit_attempt, risk

Alert when KEV vulnerabilities are detected on critical assets:

index=vulnerability sourcetype="nessus:scan" severity="Critical"
| lookup cisa_kev_lookup.csv cve_id AS CVE OUTPUT kev_status, due_date
| where kev_status="active"
| lookup asset_criticality_lookup.csv ip AS Host OUTPUT criticality
| where criticality IN ("business-critical", "mission-critical")
| table Host, CVE, plugin_name, cvss_score, kev_status, due_date, criticality

Step 5: Build Remediation Tracking Dashboard

Splunk Dashboard for Vulnerability Metrics:

-- Open vulnerabilities by severity
index=vulnerability sourcetype="nessus:scan" status="open"
| stats count by severity
| eval order = case(severity="Critical", 1, severity="High", 2, severity="Medium", 3,
                    severity="Low", 4, 1=1, 5)
| sort order

-- SLA compliance tracking
index=vulnerability sourcetype="nessus:scan" status="open"
| eval sla_days = case(
    severity="Critical", 1,
    severity="High", 7,
    severity="Medium", 30,
    severity="Low", 90
  )
| eval days_open = round((now() - first_detected) / 86400)
| eval sla_status = if(days_open > sla_days, "OVERDUE", "Within SLA")
| stats count by severity, sla_status

-- Remediation trend over 90 days
index=vulnerability sourcetype="nessus:scan"
| eval is_open = if(status="open", 1, 0)
| eval is_closed = if(status="fixed", 1, 0)
| timechart span=1w sum(is_open) AS opened, sum(is_closed) AS remediated

Step 6: Automate Remediation Ticketing

Create tickets automatically for high-priority findings:

import requests

servicenow_url = "https://company.service-now.com/api/now/table/incident"
headers = {
    "Content-Type": "application/json",
    "Authorization": f"Bearer {snow_token}"
}

for vuln in vulns:
    if vuln["risk_score"] >= 8.0:
        ticket = {
            "short_description": f"[VULN] {vuln['cve']} — {vuln['plugin_name']} on {vuln['host']}",
            "description": (
                f"Vulnerability: {vuln['plugin_name']}\n"
                f"CVE: {vuln['cve']}\n"
                f"CVSS: {vuln['cvss']}\n"
                f"Host: {vuln['host']}\n"
                f"Asset Criticality: {vuln['asset_criticality']}\n"
                f"CISA KEV: {'YES' if vuln['kev'] else 'NO'}\n"
                f"Risk Score: {vuln['risk_score']}\n"
                f"Remediation SLA: {'24 hours' if vuln['kev'] else '7 days'}"
            ),
            "urgency": "1" if vuln["kev"] else "2",
            "impact": "1" if vuln["asset_criticality"] == "business-critical" else "2",
            "assignment_group": "IT Infrastructure",
            "category": "Vulnerability"
        }
        response = requests.post(servicenow_url, headers=headers, json=ticket)
        print(f"Ticket created: {response.json()['result']['number']}")

Key Concepts

Tools & Systems

• Tenable Nessus / Tenable.io: Enterprise vulnerability scanner with 200,000+ plugin checks and compliance auditing
• Qualys VMDR: Cloud-based vulnerability management with asset discovery, prioritization, and patching integration
• OpenVAS (Greenbone): Open-source vulnerability scanner with community-maintained vulnerability feed
• CISA KEV Catalog: US government maintained list of actively exploited vulnerabilities requiring mandatory remediation
• Rapid7 InsightVM: Vulnerability management platform with live dashboards and remediation project tracking

Common Scenarios

• Zero-Day Response: New CVE published — run targeted scan for affected software, cross-reference with KEV and exploit databases
• Compliance Audit Prep: Generate PCI DSS or HIPAA vulnerability report showing scan coverage and remediation status
• Post-Patch Verification: Rescan patched systems to confirm vulnerability closure and update tracking dashboard
• Network Expansion: New subnet added to infrastructure — onboard to scan scope with appropriate policy
• Third-Party Risk: Scan externally-facing assets to validate vendor patch compliance before integration

Output Format

VULNERABILITY SCAN REPORT — Weekly Summary
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Scan Date:    2024-03-16 02:00 UTC
Scan Scope:   10.0.0.0/16 (1,247 hosts scanned)
Duration:     4h 23m
Coverage:     98.7% (16 hosts unreachable)

Findings:
  Severity     Count    New    CISA KEV
  Critical     23       5      3
  High         187      34     12
  Medium       892      78     0
  Low          1,456    112    0
  Info         3,891    201    0

Top Priority (P1 — 24hr SLA):
  CVE-2024-21762  FortiOS RCE           3 hosts   KEV: YES
  CVE-2024-1709   ConnectWise RCE       1 host    KEV: YES
  CVE-2024-3400   Palo Alto PAN-OS RCE  2 hosts   KEV: YES

SLA Compliance:
  Critical: 82% within SLA (4 overdue)
  High:     91% within SLA (17 overdue)
  Medium:   88% within SLA (107 overdue)

Tickets Created: 39 (ServiceNow)