File Extension & MIME Handling

What is File Extension & MIME Handling?

Tests how the server handles various file extensions and MIME types, looking for bypass opportunities.

This vulnerability class falls under the Configuration & Deployment Management phase of the OWASP Testing Guide (WSTG-CONF). Security engineers prioritise configuration & deployment management checks early in an assessment because weaknesses here provide a foothold that amplifies the severity of vulnerabilities found in later phases.

Security Impact

Misconfigured extension handling can allow code execution (e.g., .php.jpg bypasses). This module tests content-type enforcement.

Left undetected, file extension & mime handling issues can persist unnoticed for months. Continuous automated scanning ensures your team receives an alert the moment a regression or new exposure is introduced — long before an attacker discovers it through manual enumeration or automated offensive tooling.

How DygDog Detects It

DygDog audits server configuration, exposed file paths, HTTP methods, and deployment artefacts without sending malicious payloads, making the check safe to run continuously in production.

The File Extension & MIME Handling check is implemented as a passive scan module, meaning it never sends dangerous payloads or modifies application state. Scans complete in approximately 1.2 s and run continuously in the background so your security posture reflects the current state of your site — not a point-in-time snapshot.

Remediation Approach

Harden server and framework defaults by disabling unused HTTP methods, removing version banners from response headers, and applying a principle-of-least-privilege to file permissions and deployment artefacts.

DygDog does not stop at detection. When a File Extension & MIME Handling finding is confirmed, the platform generates infrastructure-aware, copy-paste-ready remediation snippets using frontier AI models. Instead of generic advice you need to adapt, you receive code that targets your exact server, framework, and configuration.

OWASP References

This check maps to the following OWASP Testing Guide test cases:

• WSTG-CONF-03View OWASP WSTG →

Related Configuration & Deployment Management Checks

These checks belong to the same testing phase and are often assessed together:

• TLS/SSL Configuration

  Validates HTTPS enforcement, certificate validity, protocol versions, and cipher suite strength.

• HTTP Methods Testing

  Tests for dangerous HTTP methods (TRACE, PUT, DELETE, OPTIONS) that may be unintentionally enabled.

• Security Headers Analysis

  Comprehensive check for HSTS, CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy.

• Backup & Unreferenced File Discovery

  Probes for common backup files (.bak, .old, .sql), editor artifacts (.swp, ~), and unreferenced pages.