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A critical Unauthenticated Remote Code Execution (RCE) vulnerability was discovered in mojoPortal CMS (CVE-2025-28367). This exploit demonstrates how a simple directory traversal flaw can escalate into full RCE in .NET applications.
Exploit Details:
The vulnerability arises due to insufficient input validation, allowing attackers to traverse directories and manipulate server-side files. The flaw can be exploited to upload malicious payloads, leading to arbitrary code execution.
Reference:
You Should Know:
1. Exploiting Directory Traversal in .NET
Directory traversal vulnerabilities occur when an application fails to sanitize user input, allowing access to files outside the intended directory. In .NET, this can be exploited via:
Example of a malicious path traversal payload $maliciousPath = "..\..\..\Windows\System32\cmd.exe"
2. Crafting a Malicious Payload for RCE
To achieve RCE, attackers often abuse file upload functionalities or deserialization flaws. Below is a sample PowerShell script to test for traversal:
Test for directory traversal $targetUrl = "http://vulnerable-site.com/loadfile?path=../../../../etc/passwd" Invoke-WebRequest -Uri $targetUrl
3. Bypassing Mitigations
If a patch replaces `../` with an empty string, attackers can use alternative sequences like:
– `….//`
– `%2e%2e%2f` (URL-encoded traversal)
Using curl to bypass weak filters curl "http://vulnerable-site.com/download?file=%2e%2e%2f%2e%2e%2fetc/passwd"
4. Verifying the Exploit
Check if the server processes traversal sequences by monitoring responses:
Linux command to test traversal wget http://vulnerable-site.com/../../../../etc/shadow
5. Mitigation Steps for Developers
- Use `Path.GetFullPath` in .NET to resolve absolute paths.
- Implement strict allowlists for file operations.
- Apply the latest security patches for mojoPortal CMS.
What Undercode Say:
This exploit highlights the dangers of improper input validation in web applications. Attackers can chain directory traversal with deserialization or file upload flaws to gain full system control. System administrators should:
– Monitor for unusual file access patterns (/proc/self/environ, /etc/passwd).
– Restrict web server permissions using:
Linux command to restrict directory access chmod -R 750 /var/www/html
For penetration testers, always test traversal sequences in every user-controlled input. Tools like Burp Suite or ffuf can automate this process:
Fuzzing for traversal with ffuf ffuf -u "http://target/FUZZ" -w traversal-payloads.txt
Expected Output:
A secure mojoPortal CMS instance should reject all malformed path requests with HTTP 403 or normalize paths before processing.
Related Commands for Further Testing:
Check for open .NET deserialization ports netstat -tulnp | grep "80|443|8080" Linux privilege escalation checks find / -perm -4000 -type f 2>/dev/null
Expected Output:
A hardened system should return minimal or no unexpected SUID binaries or open ports.
Conclusion:
CVE-2025-28367 is a stark reminder that even “simple” bugs can lead to catastrophic breaches. Always validate inputs, patch dependencies, and conduct regular security audits.
Expected Output:
A secure, patched mojoPortal CMS with no unauthenticated RCE risks.
References:
Reported By: Jake Mccallum – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
