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Custom app development

What has been found

Custom app development.

These products are often developed using traditional enterprise methodologies that may have slow release cycles and rely on in-house or bespoke codebases.

Why this is a potential risk

While custom applications can meet unique business needs, they often present security risks when not maintained properly:

  • Slow Patch Cycles: Applications with long development/release cycles may remain unpatched against known vulnerabilities, leaving exploitable entry points.

  • Outdated Dependencies: Legacy frameworks and libraries frequently go unmaintained, increasing exposure to publicly known vulnerabilities (e.g., OWASP A06 – Vulnerable and Outdated Components).

  • Inconsistent Security Testing: Custom codebases sometimes lack rigorous security testing (SAST, DAST, dependency checks), allowing flaws like injection, broken access control, or misconfiguration to slip through.

  • Exposure to the Internet: When custom apps are directly internet-facing, they are highly attractive to attackers seeking ransomware deployment, data theft, or initial access.

  • Knowledge Gaps: Internal teams may not follow secure development frameworks, making applications more fragile and harder to secure compared to commercial alternatives.

Custom applications increase the attack surface, and without continuous maintenance and secure development practices, they become prime targets for exploitation.

Potential solutions/Improvements

Secure Development & Maintenance

  • Align with the NIST Secure Software Development Framework (SSDF, SP 800-218) for building and maintaining secure applications.

  • Apply regular dependency and framework updates; use automated tools (e.g., SCA – Software Composition Analysis) to detect outdated or vulnerable components.

  • Enforce code reviews, static analysis, and dynamic application security testing (SAST/DAST) in the CI/CD pipeline.

  • Integrate threat modeling and security design reviews into the development lifecycle.

Deployment & Hardening

  • Restrict exposure: Place apps behind reverse proxies, WAFs, or VPNs, rather than leaving them directly internet-facing.

  • Apply the principle of least privilege to application accounts, database connections, and supporting infrastructure.

  • Ensure secure configuration baselines (disable debug modes, restrict error messages, enforce TLS 1.2+).

Governance & Monitoring

  • Maintain an application inventory with identified owners and patch responsibilities.

  • Conduct regular penetration testing and security reviews of custom apps.

  • Enable centralized logging and monitoring, and create alerts for abnormal patterns (unexpected access attempts, data exfiltration behaviors).

How to verify it is resolved:

  • Perform an external vulnerability scan to confirm no unnecessary exposure remains.

  • Validate firewall, WAF, and access controls against security baselines.

  • Confirm MFA, authentication, and encryption are enforced where access is required.

  • Monitor logs and SIEM alerts for unusual access attempts.

  • Verify dependency and patch management reports to ensure vulnerabilities are being addressed.

External references