Strategy to Audit an Existing Security Plan

An audit validates whether your security plan works as designed, covers current risks, and aligns with modern standards. The outcome should be a prioritized, time-bound remediation plan and metrics you can track quarter over quarter.

1) Define scope and goals

• Scope: Business units, apps, cloud accounts/subscriptions, environments (prod/stage/dev), and third-party integrations.
• Objectives: Verify control effectiveness, find gaps, confirm compliance (ISO 27001/NIST/CIS/PCI DSS/HIPAA/GDPR), and assess residual risk.
• Artifacts: Current security plan, risk register, network/data flow diagrams, asset inventory, policies/standards, previous audit findings (POA&M).

2) Inventory and classify assets

• Systems (servers, endpoints, mobile, OT/IoT), apps/APIs, identities (humans/service), data stores, and keys/secrets.
• Classify data (public/internal/confidential/restricted). Tie protections to classification (encryption, DLP, access guardrails).

3) Risk assessment & control mapping

• Model threats using real techniques (MITRE ATT&CK) against crown-jewel assets.
• Map required controls (e.g., CIS Controls) to threats: hardening, patching, EDR, email security, network segmentation, IAM, logging.
• Record likelihood, impact, and compensating controls to establish residual risk.

4) Controls review (design & effectiveness)

• Identity & access: MFA everywhere, least privilege, role reviews/attestation, break-glass accounts, unused accounts cleanup, SoD checks.
• Endpoint/server: EDR coverage, disk encryption, OS baseline (CIS), timely patch SLAs, application allow-listing where feasible.
• Network: Segmentation, deny-by-default, egress controls, secure remote access (VPN/IKEv2/WireGuard or ZTNA), no legacy protocols (telnet/rsh).
• Data protection: Encryption in transit (TLS 1.2+/prefer 1.3) and at rest (AES-GCM/ChaCha20-Poly1305), KMS/HSM key lifecycle, secrets management.
• Email & web: SPF/DKIM/DMARC, phishing controls, web gateway/SASE, DNS security.
• Cloud posture: CSPM/IaC scanning, least-privilege policies, secure storage (block public, versioning, object locks), certificate & key hygiene.
• Resilience: Backups (immutable/offline), tested restores, DR plans, RTO/RPO alignment.
• Physical: Facility access, visitor logs, camera retention and review cadence.

5) Logging, telemetry, and detections

Ensure you can prove control effectiveness with data.

• Centralize logs in a SIEM; retain to meet policy/regulatory needs.
• Coverage: auth events, admin/API actions, network flows, EDR alerts, cloud control-plane, DLP, KMS, and critical app logs.
• Build/validate detections for common attacks (credential abuse, lateral movement, data exfil, suspicious admin changes).

Examples

Linux (journalctl) – failed SSH auth by user:

journalctl -u ssh --since "24 hours ago" | grep -i "Failed password" | awk '{print $11}' | sort | uniq -c | sort -nr

Windows PowerShell – privileged group changes (last 7 days):

Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4728,4729,4732,4733; StartTime=(Get-Date).AddDays(-7)} |
  Select TimeCreated, Id, @{n='Account';e={$_.Properties[0].Value}}, @{n='ChangedBy';e={$_.Properties[1].Value}}

6) Vulnerability management & validation

• Automated scanning across OS, containers, images, and apps; prioritize exploitable findings (KEV/CVSS + asset criticality).
• Penetration testing for critical systems; validate fixes and ensure findings close in tracking (Jira/POA&M).

7) Compliance & policy alignment

• Verify policies exist, are versioned, and match practice (access control, crypto, secure SDLC, IR, third-party risk, privacy).
• Map evidence to control frameworks (ISO 27001 Annex A, NIST 800-53/171, PCI DSS as applicable).

8) Metrics & reporting

• Operational: Patch SLA adherence, coverage (EDR/SIEM/backup), TLS version/cipher health, MFA adoption.
• Detection/response: MTTD/MTTR, phishing fail rate, incident count by severity, containment time.
• Produce an executive summary plus a technical appendix with evidence links.

9) Remediation planning & continuous improvement

• Create a prioritized backlog with owners, timelines, and success criteria; track to closure.
• Run tabletop exercises for top risks; feed lessons learned back into policy, architecture, and detections.
• Set cadence: mini-audits monthly on high-risk areas; full program review at least annually or after major change.

Quick checklist

• Asset inventory complete and labeled by sensitivity.
• MFA + least privilege verified; dormant/admin accounts reviewed.
• All internet-facing endpoints: TLS 1.2+ (prefer 1.3), no weak ciphers; HTTP→HTTPS enforced.
• Backups: immutable + restore tested this quarter.
• SIEM: critical logs ingested with working detections; alert fatigue monitored.
• Third-party risk: contracts and security questionnaires up to date.