What Is an Application Security Checklist?

A comprehensive application security checklist ensures protection across your entire software development lifecycle (SDLC). It covers the prevention of unauthorized access, data breaches, and vulnerabilities by verifying robust authentication, encryption, secure configuration, and proactive testing.

These checklists are typically informed by frameworks such as OWASP, NIST, or ISO standards. They provide actionable items ranging from secure coding practices to deployment hardening. Here are some of the key areas to include in a checklist:

Planning and requirements: Define security requirements, threat models, compliance obligations, and risk acceptance criteria before development begins.
Architecture and design: Design secure architectures using principles such as least privilege, defense in depth, and secure defaults.
Secure coding: Follow secure coding standards and use automated code analysis to prevent common implementation flaws.
Dependency and open-source security: Continuously inventory, scan, and update third-party components to reduce software supply chain risk.
Authentication and session management: Protect user identities with strong authentication, secure session handling, and multi-factor authentication where appropriate.
Authorization and access control: Enforce least privilege and verify authorization on every request to prevent unauthorized access.
API security: Secure APIs through authentication, input validation, rate limiting, and continuous monitoring.
Data protection: Encrypt sensitive data, minimize collection, and apply appropriate controls throughout the data lifecycle.
Secrets management: Store, rotate, and protect credentials, API keys, certificates, and encryption keys using dedicated secret management solutions.
Configuration and environment security: Harden systems, remove insecure defaults, and continuously validate configuration settings across environments.
CI/CD and DevSecOps controls: Integrate automated security testing, policy enforcement, and artifact verification into development pipelines.
Testing and validation: Validate security controls using SAST, DAST, penetration testing, and manual security reviews before release.
Runtime protection and monitoring: Continuously detect attacks, monitor application activity, and generate alerts for suspicious behavior in production.
Release and production readiness: Verify that security requirements, monitoring, backup procedures, and incident response capabilities are in place before deployment.

In this article:

Why Application Security Matters
Application Security Checklist by SDLC Stage

Why Application Security Matters

Applications Are a Primary Attack Surface

Modern applications are exposed to the internet and interact with users, systems, and data, making them a frequent target for attackers. Unlike traditional network perimeters, application boundaries are porous and constantly shifting due to rapid development cycles, third-party integrations, and cloud adoption. Attackers exploit weaknesses in applications to gain unauthorized access, exfiltrate data, or disrupt services, often bypassing other security controls.

The prevalence of web, mobile, and API-driven applications has expanded the attack surface significantly. Organizations that neglect application security risk not just direct breaches but also the loss of customer trust and regulatory penalties.

Vulnerabilities Can Quickly Become Exploitable Risks

Software vulnerabilities (such as injection flaws, broken authentication, or insecure dependencies) can be rapidly discovered and exploited by attackers. Publicly disclosed vulnerabilities are often weaponized within days, sometimes hours, of release. The widespread use of automated scanning tools and exploit kits means that even obscure or newly introduced vulnerabilities can quickly become high-risk if not addressed.

Organizations must prioritize rapid identification and remediation of vulnerabilities throughout the SDLC. Delays in patching or mitigating issues can lead to significant business impacts, including data breaches, service outages, and reputational damage. A proactive approach, supported by a comprehensive security checklist, helps ensure vulnerabilities are addressed before they can be exploited.

Application Risk Extends Beyond the Codebase

Application risk is not limited to software code. Misconfigurations, insecure deployment environments, and poorly managed secrets can introduce vulnerabilities that are independent of the application logic. Attackers often target infrastructure or operational weaknesses, such as exposed admin interfaces, default credentials, or insufficient monitoring, to gain access or escalate privileges.

The integration of third-party services, APIs, and cloud components means that application risk must be assessed holistically. A robust application security checklist addresses not just development practices, but also deployment, configuration, and ongoing monitoring. This ensures that security is maintained across the entire lifecycle and technology stack, reducing the likelihood of overlooked vulnerabilities.

Related content: Read our guide to cloud application security.

Application Security Checklist by SDLC Stage

1. Planning and Requirements

Security planning begins before any code is written. Defining security requirements early helps prevent design flaws, reduces costly rework, and ensures security is treated as a core project objective rather than a final validation step.

Define security requirements: Document security, privacy, and regulatory requirements alongside functional requirements.
Perform threat modeling: Identify likely attack scenarios, high-value assets, and possible abuse cases.
Classify sensitive data: Determine what data the application handles and define appropriate protection measures.
Establish security acceptance criteria: Include measurable security requirements for features before they are considered complete.
Plan security testing: Define when code reviews, scanning, penetration testing, and other assessments will occur.
Identify compliance obligations: Map application requirements to relevant standards, laws, and internal policies.
Define data retention rules: Specify how long sensitive data is stored and when it must be deleted.
Set risk tolerance: Agree on which security risks must be fixed before release.
Assign security ownership: Define who is responsible for security decisions, reviews, and approvals.
Document abuse cases: Describe how attackers or malicious users could misuse application features.
Include privacy requirements: Define consent, data minimization, and user data rights requirements.
Plan incident response needs: Identify logs, alerts, and workflows needed to support future investigations.

2. Architecture and Design

Many security issues originate from architectural decisions rather than implementation mistakes. Designing security into the application’s architecture helps reduce the attack surface, enforce trust boundaries, and establish strong security controls that remain effective throughout the application’s lifecycle.

Apply secure design principles: Use least privilege, defense in depth, and secure defaults throughout the architecture.
Reduce attack surface: Remove unnecessary services, interfaces, and components.
Design secure data flows: Protect sensitive data in transit and at rest using appropriate encryption.
Segment critical components: Separate public-facing services from internal systems where possible.
Review architecture for risks: Conduct security design reviews before implementation begins.
Use secure defaults: Configure components to deny access unless explicitly allowed.
Isolate trust boundaries: Clearly separate user-controlled, internal, and privileged system areas.
Design for secret management: Use a secure vault or managed secret service instead of local files.
Choose proven security controls: Prefer tested libraries and platform features over custom security logic.
Protect administrative interfaces: Restrict admin access using strong authentication and network controls.
Plan for secure logging: Ensure logs capture useful events without storing sensitive data.
Design failure states safely: Ensure errors, service failures, and timeouts do not expose data or bypass security controls.

3. Secure Coding

Secure coding practices reduce the likelihood of introducing vulnerabilities during development. Combining secure coding standards with automated scanning and peer reviews helps detect security issues before they reach production.

Validate all inputs: Reject unexpected or malformed input using allowlists where practical.
Encode output: Prevent injection and cross-site scripting by using context-appropriate output encoding.
Handle errors securely: Avoid exposing sensitive system details in error messages.
Protect sensitive data: Never hardcode credentials, secrets, or encryption keys.
Use static analysis: Run automated code scanning and address identified security findings.
Use parameterized queries: Prevent SQL injection by avoiding dynamic query construction.
Avoid unsafe deserialization: Do not deserialize untrusted data unless strict controls are in place.
Normalize input before validation: Convert input to a standard format before applying validation rules.
Use approved cryptography: Rely on vetted cryptographic libraries instead of custom algorithms.
Review security-critical code: Manually inspect authentication, authorization, payment, and data access logic.
Prevent race conditions: Protect workflows where timing issues could affect security decisions.
Disable debug features: Remove debug endpoints, stack traces, and development configurations from production.

4. Dependency and Open-Source Security

Modern applications depend heavily on third-party components, making dependency management an essential part of application security. Regularly monitoring, updating, and reviewing external libraries helps reduce exposure to publicly known vulnerabilities.

Maintain a software inventory: Track all third-party libraries and components.
Scan for known vulnerabilities: Regularly check dependencies against vulnerability databases.
Keep dependencies updated: Apply security patches and supported versions promptly.
Remove unused packages: Eliminate unnecessary dependencies to reduce exposure.
Verify package sources: Download dependencies only from trusted repositories and verify their integrity.
Use lockfiles: Pin dependency versions to produce repeatable builds.
Review transitive dependencies: Assess packages introduced indirectly through other libraries.
Monitor end-of-life components: Replace unsupported frameworks, runtimes, and packages.
Check license risks: Review open-source licenses for legal and operational concerns.
Use private package controls: Restrict who can publish or modify internal packages.
Prevent dependency confusion: Configure package managers to prioritize trusted internal repositories.
Review major updates carefully: Evaluate significant dependency changes before deployment.

5. Authentication and Session Management

Authentication verifies user identities, while session management maintains trust after login. Weak authentication or poorly protected sessions can allow attackers to impersonate users or gain unauthorized access.

Require strong authentication: Enforce strong passwords and support multi-factor authentication where appropriate.
Store passwords securely: Hash passwords using modern algorithms with unique salts.
Protect session tokens: Generate unpredictable session identifiers and transmit them only over HTTPS.
Configure secure cookies: Enable Secure, HttpOnly, and SameSite cookie attributes.
Expire sessions appropriately: Implement idle timeouts and invalidate sessions after logout or credential changes.
Prevent credential stuffing: Use rate limiting, breached password detection, and anomaly monitoring.
Secure account recovery: Protect password reset workflows with short-lived, single-use tokens.
Require reauthentication: Request fresh authentication before sensitive account changes.
Limit login error details: Avoid revealing whether usernames or passwords are valid.
Rotate session tokens: Generate new session identifiers after authentication and privilege changes.
Monitor authentication events: Log successful logins, failed attempts, and suspicious authentication activity.
Invalidate compromised sessions: Allow administrators or automated systems to revoke active sessions when needed.

6. Authorization and Access Control

Authorization determines what authenticated users are allowed to access or modify. Consistent access control enforcement helps prevent privilege escalation, unauthorized data access, and accidental exposure of sensitive resources.

Enforce server-side authorization: Never rely on client-side permission checks.
Apply least privilege: Grant users and services only the permissions they require.
Validate access on every request: Check authorization before accessing protected resources.
Use role- or attribute-based access control: Implement a consistent authorization model.
Log privileged actions: Record administrative and security-sensitive operations.
Deny by default: Block access unless a rule explicitly grants permission.
Prevent insecure direct object references: Verify users are authorized to access requested objects.
Separate duties: Avoid assigning conflicting administrative privileges to a single account.
Restrict service accounts: Limit machine identities to the minimum required permissions.
Review permission changes: Audit role assignments and privilege modifications.
Test authorization logic: Include negative tests that verify unauthorized access is denied.
Enforce tenant isolation: Ensure users cannot access resources belonging to other tenants.

7. API Security

APIs expose application functionality directly to users, services, and third-party systems. Protecting API endpoints requires strong authentication, strict validation, controlled data exposure, and continuous monitoring.

Authenticate API requests: Require secure authentication for protected endpoints.
Validate request data: Verify parameters, payloads, and headers before processing.
Implement rate limiting: Prevent abuse, brute-force attacks, and denial-of-service attempts.
Restrict data exposure: Return only the information required for each request.
Monitor API activity: Log requests and detect suspicious behavior.
Validate HTTP methods: Allow only the methods required by each endpoint.
Use schema validation: Enforce strict request and response formats.
Prevent mass assignment: Allow updates only to explicitly approved fields.
Version APIs securely: Deprecate and remove outdated API versions.
Limit payload size: Reject excessively large requests that could impact availability.
Secure webhooks: Verify signatures, timestamps, and request origins before processing.
Use consistent error responses: Avoid exposing implementation details through API error messages.

8. Data Protection

Protecting sensitive data is one of the primary goals of application security. Data should be secured throughout its lifecycle, including collection, storage, transmission, processing, sharing, and deletion, to reduce the risk of unauthorized access or disclosure.

Classify sensitive data: Identify regulated, confidential, and business-critical information handled by the application.
Encrypt data at rest: Protect stored sensitive data using strong, industry-approved encryption algorithms.
Encrypt data in transit: Require TLS for all communications involving sensitive information.
Minimize data collection: Collect only the information necessary for business purposes.
Mask sensitive data: Prevent confidential information from appearing in logs, error messages, and user interfaces.
Tokenize or anonymize data: Replace sensitive values where full data is not required.
Implement secure data deletion: Remove data securely when it is no longer needed.
Protect backups: Encrypt and control access to backup data.
Restrict data access: Limit access to sensitive information based on business need.
Monitor sensitive data access: Log and review access to confidential records and high-value datasets.
Prevent data leakage: Implement controls to reduce accidental exposure through APIs, reports, or exports.
Validate encryption key usage: Ensure encryption keys are managed separately from protected data.

9. Secrets Management

Applications rely on secrets such as passwords, API keys, certificates, and encryption keys to communicate securely with other systems. Proper secrets management reduces the risk of credential theft and unauthorized system access.

Use a dedicated secret manager: Store secrets in a secure vault rather than application code or configuration files.
Never hardcode secrets: Remove passwords, API keys, and tokens from source code.
Rotate secrets regularly: Replace credentials on a scheduled basis or after suspected compromise.
Limit secret access: Grant access only to authorized users, applications, and services.
Use short-lived credentials: Prefer temporary tokens over long-lived secrets whenever possible.
Audit secret access: Log retrieval, modification, and deletion of sensitive credentials.
Encrypt stored secrets: Protect secrets using strong encryption.
Protect environment variables: Restrict access to runtime configuration containing sensitive values.
Automatically detect exposed secrets: Scan repositories and CI/CD pipelines for leaked credentials.
Revoke compromised secrets immediately: Replace exposed credentials without delay.
Manage certificates securely: Track certificate expiration and automate renewals where possible.
Separate secrets by environment: Use different credentials for development, testing, and production.

10. Configuration and Environment Security

Secure applications depend on secure environments. Configuration errors are a common cause of security incidents, making continuous configuration review and hardening essential across development and production systems.

Disable unnecessary services: Remove or disable unused features and network services.
Replace default credentials: Change vendor-provided usernames and passwords before deployment.
Apply secure configuration baselines: Standardize hardened configurations across environments.
Separate environments: Isolate development, testing, staging, and production systems.
Protect administrative interfaces: Restrict management access using authentication and network controls.
Enforce HTTPS everywhere: Redirect all traffic to encrypted connections.
Configure security headers: Use headers such as CSP, HSTS, and X-Frame-Options where appropriate.
Restrict network exposure: Limit inbound and outbound connectivity to required services only.
Manage configuration changes: Track and review changes through version control and approval processes.
Remove test components: Eliminate sample applications, test accounts, and development tools before release.
Harden containers and hosts: Reduce unnecessary software and apply security patches regularly.
Review cloud configurations: Verify storage, identity, networking, and access settings are securely configured.

11. CI/CD and DevSecOps Controls

Integrating security into CI/CD pipelines enables vulnerabilities to be identified before deployment. Automated security checks help maintain consistent standards while supporting rapid software delivery.

Scan source code automatically: Run static application security testing during builds.
Scan dependencies: Detect vulnerable third-party packages before deployment.
Check infrastructure as code: Analyze infrastructure templates for security misconfigurations
Enforce build policies: Block releases that fail defined security requirements.
Sign build artifacts: Verify the integrity and authenticity of deployment packages.
Protect CI/CD credentials: Secure pipeline accounts, tokens, and service credentials.
Restrict pipeline permissions: Apply least privilege to automation tools and runners.
Generate software bills of materials: Produce SBOMs for dependency visibility.
Scan container images: Identify vulnerabilities before images are published.
Verify artifact integrity: Validate checksums and signatures throughout the deployment process.
Audit pipeline activity: Record build, deployment, and configuration changes.
Automate security updates: Integrate dependency updates and security fixes into development workflows.

12. Testing and Validation

Security testing validates that implemented controls work as intended and identifies weaknesses before attackers can exploit them. Multiple testing techniques provide broader coverage than relying on a single assessment method.

Perform Static Application Security Testing (SAST): Analyze source code for security issues.
Perform Dynamic Application Security Testing (DAST): Test running applications for exploitable vulnerabilities.
Conduct penetration testing: Simulate realistic attacks against the application.
Review security controls: Verify authentication, authorization, encryption, and logging functions correctly.
Test input validation: Confirm applications properly handle malformed and unexpected input.
Validate business logic: Identify workflow flaws that automated scanners may miss.
Test APIs separately: Assess API-specific authentication, authorization, and data handling.
Verify security fixes: Confirm vulnerabilities have been fully remediated before release.
Perform regression testing: Ensure security fixes do not introduce new vulnerabilities.
Test error handling: Verify failures do not expose sensitive information.
Assess third-party integrations: Evaluate external services for secure communication and access controls.
Track and prioritize findings: Record vulnerabilities and assign remediation based on real exploitability and business impact, not scanner severity alone.

13. Runtime Protection and Monitoring

Security does not end after deployment. Continuous monitoring and runtime protections help detect attacks, contain incidents, and provide visibility into suspicious activity affecting production applications.

Enable centralized logging: Collect application and security logs in a central location.
Monitor authentication events: Detect suspicious login attempts and account activity.
Detect anomalous behavior: Identify unusual access patterns or unexpected application activity.
Deploy a web application firewall (WAF): Block common web attacks before they reach the application.
Implement runtime application protection: Detect and prevent attacks while the application is running.
Monitor API activity: Track abnormal API usage and abuse.
Generate security alerts: Notify security teams of high-risk events.
Protect log integrity: Prevent unauthorized modification or deletion of audit logs.
Monitor resource usage: Detect denial-of-service attempts and resource exhaustion.
Collect audit trails: Maintain records of privileged actions and security events.
Integrate with SIEM platforms: Correlate application events with other security telemetry.
Review monitoring rules regularly: Update detections to address evolving threats.

14. Release and Production Readiness

Before deploying an application, organizations should verify that security requirements have been met and operational safeguards are in place. A structured release review helps reduce the likelihood of introducing preventable security issues into production.

Complete security reviews: Verify required assessments have been performed before release.
Resolve critical vulnerabilities: Fix high-risk issues or formally document accepted risks.
Verify secure configurations: Confirm production settings match approved security baselines.
Confirm monitoring is enabled: Ensure logging, alerting, and auditing are operational.
Validate backup and recovery: Test restoration procedures before production deployment.
Review access permissions: Remove unnecessary accounts and excessive privileges.
Verify secrets and certificates: Confirm production credentials are valid and securely managed.
Prepare rollback procedures: Establish a tested process for reverting failed deployments.
Document security exceptions: Record approved deviations from security requirements.
Confirm incident response readiness: Ensure contacts, escalation paths, and response procedures are current.
Perform a final security checklist review: Validate that all required security controls have been completed.
Monitor post-deployment: Closely observe the application after release for unexpected behavior or security events.

Run This Application Security Checklist End-to-End with Maze Code

Working through an application security checklist surfaces a large volume of potential issues across your own code and your dependencies, and the hard part is knowing which findings actually matter. Maze Code applies AI agents to the code your team writes and the third-party components it relies on, finding vulnerabilities, investigating each one the way an expert security engineer would, and proving what is genuinely exploitable in your environment rather than merely present or reachable. Findings that matter reach your team with full technical context and a routed fix, while those that are not exploitable are closed before they ever hit your backlog.

Key capabilities of Maze Code:

AI-SAST for the code you write: Instead of matching code against known patterns, Maze agents understand what the code actually does, surfacing novel vulnerabilities and complex business-logic flaws that pattern-based scanners miss, then evaluating each for exploitability in your environment.
AI-SCA for dependencies: Maze finds every vulnerable dependency and uses AI-built call graphs to determine exploitability with context from your code and cloud, prioritizing the ones that create real risk for your organization.
Exploitability, not just reachability: Agents trace the full call chain, however many hops deep a vulnerability sits, then check runtime and cloud context to prove what is exploitable, automatically closing findings that are reachable but cannot be exploited in practice.
Developer-ready remediation: Agents write fixes that match your code, identify the developer who owns it, and ship the pull request directly to them; when no fix exists yet, they recommend a mitigation instead.
One investigation across code and cloud: Running on the same platform as Maze Cloud, agents mesh code and cloud findings so code context enriches cloud and cloud context enriches code, leaving one unified ticket per issue instead of duplicates.
Fits your existing workflow: Maze Code runs in your CI/CD pipeline (GitHub Actions, GitLab CI, CircleCI), surfaces findings right at the pull request, and can ingest and dedupe results from the scanners you already run.

To see how Maze’s AI agents investigate, prove, and fix application vulnerabilities the way your best security engineer would, explore Maze Code.

Application Security Checklist: 14 Steps Across the SDLC