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While testing Microsoft’s web applications, security researcher Rohit Kamble discovered an open redirect vulnerability on an official Microsoft Developer domain. Open redirects may seem minor, but they can facilitate phishing attacks by tricking users into visiting malicious sites disguised as trusted Microsoft links.
You Should Know:
1. How Open Redirects Work
Open redirect vulnerabilities occur when a website allows unvalidated URLs as parameters in redirects. Attackers exploit this to redirect victims to phishing or malware sites.
2. Testing for Open Redirects
Use these methods to identify open redirects:
- Manual Testing:
Modify URL parameters like:
https://microsoft.com/redirect?url=https://evil.com
Check if the site redirects without validation.
- Automated Scanning with Burp Suite:
Use Burp Scanner or OWASP ZAP to detect open redirects in web applications. -
Command-Line Testing with cURL:
curl -I "https://target.com/redirect?url=http://malicious.com"
Look for `Location: http://malicious.com` in headers.
3. Exploiting Open Redirects for Phishing
Attackers craft URLs like:
https://microsoft.com/safe?redirect=https://evil.com/login
Users see a Microsoft domain but land on a fake login page.
4. Mitigation Techniques
- Whitelist allowed domains:
$allowed_domains = ["microsoft.com", "trusted.org"]; if (!in_array(parse_url($redirect_url, PHP_URL_HOST), $allowed_domains)) { die("Invalid redirect"); } - Use relative URLs instead of full external links.
- Implement token-based validation for redirects.
5. Reporting Vulnerabilities
If you find a bug:
1. Document steps to reproduce.
- Submit via the vendor’s bug bounty program (e.g., Microsoft Security Response Center).
- Avoid public disclosure before a fix is released.
What Undercode Say
Open redirects may not always qualify for bounties, but they highlight weak input validation. Ethical hacking isn’t just about rewards—it’s about persistence, curiosity, and responsible disclosure. Keep testing, keep learning, and contribute to a safer web.
Expected Output:
A security report detailing the open redirect flaw, PoC, and remediation steps.
Prediction
As phishing attacks grow, vendors will enforce stricter redirect validation, making open redirects harder to exploit. Automated scanning tools will integrate deeper checks for such flaws.
URLs referenced:
References:
Reported By: Mr Rohit – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
