What Should a Security Audit Cover?

Key Takeaway: A thorough security audit covers five areas: application security (OWASP Top 10), infrastructure and network security, access control and authentication, data protection and privacy (including GDPR compliance), and incident response readiness. The checklist below is designed for product teams who want to understand what a security audit should include before, during, and after engaging a specialist.

What Is a Security Audit and How Is It Different from a Penetration Test?

A security audit is a systematic evaluation of your entire security posture, covering policies, procedures, technical controls, and compliance status. It is broader and more structured than a penetration test, which focuses specifically on attempting to exploit vulnerabilities in targeted systems.

Think of it this way: a penetration test asks "can an attacker break in?" A security audit asks "is our overall approach to security adequate?" The audit examines not just whether your walls have holes, but whether you have walls in the right places, whether someone is watching the walls, and whether you have a plan for when something gets through.

A comprehensive security audit typically includes:

Technical assessment: Vulnerability scanning, configuration reviews, code analysis
Process review: Incident response procedures, change management, access provisioning
Compliance evaluation: Mapping current state against regulatory requirements (GDPR, NIS2, PCI DSS)
Policy analysis: Security policies, acceptable use policies, data handling procedures
Human factors: Security awareness, phishing susceptibility, privileged access management

For organizations in the European Union, the audit increasingly needs to account for the NIS2 Directive, which expanded cybersecurity requirements to a broader set of sectors and imposes stricter incident reporting obligations. A security audit should evaluate your readiness against these requirements before the compliance deadline, not after.

Most organizations benefit from conducting a full security audit annually, with targeted assessments (penetration tests, vulnerability scans) on a quarterly basis or after significant changes.

What Does the OWASP Top 10 Cover and Why Should You Care?

The OWASP Top 10 is a regularly updated list of the most critical web application security risks, maintained by the Open Web Application Security Project. It represents the baseline that every web application should be tested against, and auditors use it as a standard framework for application security assessments.

The current OWASP Top 10 categories include:

1. Broken Access Control. Users can act outside their intended permissions. This is the most common vulnerability category. Examples include accessing another user's data by changing an ID in the URL, or performing admin actions without admin privileges.

2. Cryptographic Failures. Sensitive data is exposed due to weak or missing encryption. This includes transmitting data over HTTP instead of HTTPS, storing passwords in plaintext, using deprecated algorithms (MD5, SHA-1 for passwords), or exposing API keys in client-side code.

3. Injection. Untrusted data is sent to an interpreter (SQL, NoSQL, LDAP, OS commands) as part of a command or query. SQL injection remains common despite being well-understood, often through ORM misuse or raw query construction with string concatenation.

4. Insecure Design. Security flaws baked into the architecture that cannot be fixed with better implementation. Examples include business logic that allows unlimited login attempts, account enumeration through different error messages, or missing rate limiting on sensitive operations.

5. Security Misconfiguration. Default credentials left unchanged, unnecessary features enabled, error messages exposing stack traces, cloud storage buckets left publicly accessible. These are among the easiest vulnerabilities to find and exploit.

6. Vulnerable and Outdated Components. Using libraries, frameworks, or other software components with known vulnerabilities. This is particularly insidious because the vulnerability is not in your code but in a dependency you may not be actively monitoring.

7. Identification and Authentication Failures. Weak password policies, missing multi-factor authentication, session management issues, and credential stuffing vulnerabilities.

8. Software and Data Integrity Failures. Relying on plugins, libraries, or CI/CD pipelines without verifying their integrity. Supply chain attacks target this category.

9. Security Logging and Monitoring Failures. Insufficient logging means breaches go undetected. If you cannot tell that an attack happened, you cannot respond to it.

10. Server-Side Request Forgery (SSRF). The application fetches remote resources without validating the user-supplied URL, allowing attackers to access internal services.

Every security audit should systematically test your application against these categories. They represent the vulnerabilities that attackers most commonly exploit in the real world.

What Should Your Application Security Checklist Include?

Application security is the layer closest to your users and your data. Your audit checklist should cover authentication, authorization, input handling, data protection, and session management at minimum.

Authentication and Session Management:

Multi-factor authentication (MFA) available for all user accounts
Strong password policy enforced (minimum length, complexity, breach database checking)
Account lockout or rate limiting after failed login attempts
Session tokens generated with cryptographically secure randomness
Sessions expire after a reasonable inactivity period
Session invalidation on password change and logout
Secure cookie attributes set (HttpOnly, Secure, SameSite)

Authorization and Access Control:

Role-based or attribute-based access control implemented consistently
Server-side authorization checks on every request (not just UI-level hiding)
Principle of least privilege applied to all roles and service accounts
API endpoints enforce authorization independently of the frontend
Admin functionality separated and additionally protected

Input Validation and Output Encoding:

All user input validated on the server side (client-side validation is not security)
Parameterized queries used for all database operations (no string concatenation)
Output encoding applied to prevent Cross-Site Scripting (XSS)
File uploads restricted by type, size, and stored outside the web root
Content Security Policy (CSP) headers configured

Data Protection:

All data transmitted over TLS 1.2 or higher (no mixed content)
Sensitive data encrypted at rest (database encryption, encrypted backups)
Passwords hashed using bcrypt, scrypt, or Argon2 (never MD5 or plain SHA)
API keys and secrets stored in environment variables or secret managers (not in code)
Personally identifiable information (PII) handling compliant with GDPR requirements

Error Handling and Logging:

Error messages do not expose stack traces, database details, or internal paths
Security-relevant events logged (login attempts, access control failures, input validation failures)
Logs stored securely and retained for a period compliant with your regulatory requirements
Monitoring and alerting configured for anomalous patterns

How Should You Audit Your Infrastructure and Network Security?

Infrastructure security covers the servers, networks, and cloud services that host your application. Misconfigured infrastructure is one of the most common attack vectors, particularly as organizations migrate to cloud platforms where the default configurations are not always secure.

Server and Cloud Configuration:

Operating systems and software patched and up to date
Unnecessary services and ports disabled
Default credentials changed on all systems (databases, admin panels, network devices)
Cloud IAM policies follow the principle of least privilege
Cloud storage buckets and resources have appropriate access controls (no public access unless intentional)
Infrastructure as Code (IaC) templates reviewed for security misconfigurations

Network Security:

Firewalls configured to allow only necessary traffic
Network segmentation separates public-facing systems from internal infrastructure
VPN or zero-trust architecture for remote access to internal systems
DNS configuration secured against zone transfer and hijacking
DDoS protection in place for public-facing services

Container and Deployment Security:

Container images scanned for known vulnerabilities before deployment
Containers run as non-root users with minimal capabilities
Secrets not baked into container images
CI/CD pipeline secured (access controls, signed artifacts, audit trail)
Deployment process uses immutable infrastructure where possible

Backup and Recovery:

Regular automated backups of critical data and configurations
Backups encrypted and stored in a separate location
Backup restoration tested periodically (untested backups are not backups)
Recovery Time Objective (RTO) and Recovery Point Objective (RPO) defined and achievable

What Access Controls and Compliance Requirements Should the Audit Verify?

Access control and compliance represent the organizational side of security. Technical controls are only effective when supported by policies, processes, and proper management of who can access what.

Access Management:

User access reviews conducted at least quarterly
Offboarding process revokes all access within 24 hours of departure
Shared accounts eliminated or minimized with individual accountability
Privileged access (admin, root, database) requires approval and is logged
Third-party vendor access scoped, time-limited, and monitored
Service accounts inventoried with documented purposes and owners

GDPR Compliance (for EU organizations):

Data Processing Records maintained (Article 30)
Privacy Impact Assessments conducted for high-risk processing
Data Subject Access Requests (DSAR) process documented and tested
Data retention periods defined and automated where possible
Data breach notification process established (72-hour reporting to supervisory authority)
Data Processing Agreements in place with all processors and sub-processors
Lawful basis identified and documented for each processing activity

NIS2 Directive Readiness (if applicable):

Risk management measures implemented for network and information systems
Incident handling procedures established with defined escalation paths
Business continuity and crisis management plans in place
Supply chain security assessed (security requirements for suppliers)
Cybersecurity training program established for management and staff
Vulnerability handling and disclosure policies documented

Industry-Specific Compliance:

PCI DSS if processing payment card data (quarterly scans, annual assessment)
HIPAA if handling health data (relevant for EU companies serving US markets)
Sector-specific NIS2 requirements for essential and important entities

The audit should produce a compliance gap analysis that maps your current state against each applicable requirement, identifies gaps, and prioritizes remediation based on risk and regulatory deadlines.

How Do You Prepare for a Security Audit?

Preparation determines how efficiently the audit proceeds and how useful the results are. A well-prepared organization gets more value from the same audit engagement because the auditors spend time finding issues rather than gathering basic information.

Documentation to gather before the audit:

Network architecture diagrams (current, not aspirational)
Application architecture documentation
List of all systems, services, and third-party integrations in scope
Existing security policies and procedures
Previous audit reports and remediation status
User access lists for critical systems
Vendor and third-party access inventory

Technical preparation:

Ensure auditors have appropriate test accounts and access
Set up a staging environment that mirrors production (if the audit includes penetration testing)
Identify a technical point of contact who can answer questions about architecture and configuration
Document any known issues or compensating controls already in place

Organizational preparation:

Define the audit scope clearly (which systems, which locations, which compliance frameworks)
Identify stakeholders who need to be informed of findings
Establish a communication channel between the audit team and your technical team
Set expectations for the timeline: audit execution, draft report, final report

After the audit:

Review findings with both technical and business stakeholders
Prioritize remediation based on risk rating and business impact
Assign owners and deadlines for each finding
Schedule re-testing of critical findings after remediation
Plan the next audit cycle

At Atium, our security audit engagements follow this structured approach. We work with your team to define scope, execute the assessment, and deliver actionable findings that are prioritized by real-world risk, not just theoretical severity scores.

FAQ

How often should we conduct a security audit?

Conduct a comprehensive security audit annually at minimum. Additionally, perform targeted assessments after major infrastructure changes (cloud migration, new application launch), significant organizational changes (mergers, rapid hiring), or security incidents. Vulnerability scanning should happen quarterly, and critical systems should have continuous monitoring. Organizations subject to NIS2 or PCI DSS may have specific audit frequency requirements defined by the regulation.

How long does a security audit take?

A focused application security audit takes one to two weeks. A comprehensive audit covering applications, infrastructure, policies, and compliance typically takes three to six weeks, depending on the size and complexity of the environment. The audit itself is usually the shorter part; preparation and remediation take longer. Plan for two to three months from audit kickoff to completion of critical remediation items.

What is the difference between an internal and external security audit?

An internal audit is conducted by your own security or IT team and focuses on ongoing compliance and process adherence. An external audit is conducted by an independent third party and provides an unbiased assessment of your security posture. External audits carry more weight with regulators, customers, and partners because they are independent. Most organizations benefit from both: regular internal assessments supplemented by annual external audits.

Do we need a security audit if we use cloud services like AWS or Azure?

Yes. Cloud providers operate on a shared responsibility model where they secure the underlying infrastructure, but you are responsible for securing your configurations, applications, data, and access controls. Misconfigured cloud environments are among the most common sources of data breaches. A security audit should specifically review your cloud configurations, IAM policies, storage permissions, and network settings.

What happens if the audit finds critical vulnerabilities?

Critical vulnerabilities should be remediated immediately, typically within 24 to 48 hours for actively exploitable issues. The audit report will classify findings by severity (critical, high, medium, low) with recommended remediation steps. Your team should have a pre-agreed escalation process for critical findings, including who is authorized to approve emergency changes and how to communicate the risk to stakeholders.

How much does a security audit cost?

Costs depend on scope and depth. A focused web application security assessment might cost 5,000 to 15,000 euros. A comprehensive audit covering multiple applications, infrastructure, cloud environments, and compliance frameworks typically ranges from 15,000 to 50,000 euros. Ongoing managed security assessments with quarterly testing and continuous monitoring are priced as annual retainers. The cost is best evaluated against the potential cost of a security breach, which averages several hundred thousand euros for SMBs in the EU.