SAP ICF URL redirection Vulnerability
Description
This endpoint is vulnerable to open URL redirection, allowing attackers to manipulate URL parameters to redirect users to external malicious websites. When user-supplied input is used to construct redirect URLs without proper validation, attackers can craft links that appear legitimate but redirect victims to phishing sites or malware distribution pages. This vulnerability is commonly exploited in social engineering attacks where the trusted domain name lends credibility to malicious links.
Remediation
Implement proper input validation and sanitization for all URL redirect parameters:
1. Use an allowlist approach: Maintain a list of approved redirect destinations and validate all redirect URLs against this list
2. Validate redirect URLs: Ensure redirect targets are relative paths or belong to trusted domains
// Example: Java validation
String redirectUrl = request.getParameter("redirect");
if (redirectUrl != null && !redirectUrl.startsWith("/") &&
!redirectUrl.startsWith("https://trusted-domain.com")) {
// Reject or default to safe URL
redirectUrl = "/default-page";
}
3. Avoid user-controlled redirects: Where possible, use indirect references (e.g., numeric IDs mapped to URLs server-side) instead of accepting full URLs as parameters
4. Implement URL parsing: Parse and validate the protocol, domain, and path components before performing redirects
5. Display warnings: If external redirects are necessary, show users an interstitial page warning them they are leaving your site