Technical Report
Detailed analysis for technical teams, covering methodologies, tools, and findings.
Technical Security Report: "Corridor" System
Purpose of the Report
This technical report outlines the steps taken to exploit an IDOR vulnerability in the Corridor machine, a beginner-level CTF challenge focused on insecure object references in web applications.
Methodology
Navigate to the target URL and examine the web layout.
Analyze the behavior of door selection and corresponding URLs.
Use CrackStation to reverse MD5 hashes.
Identify the logic mapping door numbers to hashes.
Use CyberChef to generate new MD5 hashes for custom values.
Inject new hashes into the URL to probe unauthorized data.
Detailed Findings
Reconnaissance
The web interface shows 13 doors.
Each door redirects to a URL containing an MD5 hash.
Example:
/room.php?id=d3c8d9...
Gaining Access
Reversing the hash from Door 1 using CrackStation reveals the number
1.Confirmed that each hash corresponds to its respective door number.
Generated MD5 hashes for
0and14using CyberChef.
Exploitation
By replacing the hash in the URL with the MD5 of
0, we accessed content not available from the UI.This URL revealed the flag, completing the challenge.
Recommendations
Never rely on client-side obfuscation as access control.
Enforce server-side authorization checks for object access.
Avoid MD5 for security-related operations.
Use secure, opaque identifiers and validate permissions explicitly.
Conclusion
The exploitation of the Corridor machine highlighted a classic IDOR flaw, easily identified and exploited using basic tools and logic. In a real-world context, this vulnerability could expose critical data and functionalities.
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