CRITICAL
Rule Definition
Attackers may use phishing techniques or steal credentials. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect.
Remediation
Assume all input is malicious.
Avoid using inputs. If it is not possible, use an "accept known good" input validation strategy, i.e., use stringent white-lists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack.
Violation Code Sample
String url = request.getParameter("url");
response.sendRedirect(url);
Fixed Code Sample
String url = request.getParameter("url");
//code a validate function for the input recieved "url"
response.sendRedirect(url);
Reference
CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
https://cwe.mitre.org/data/definitions/601.html
Open Web Application Security Project (OWASP)
https://www.owasp.org/index.php/Top_10_2013-A10-Unvalidated_Redirects_and_Forwards
Related Technologies
Technical Criterion
Secure Coding - Input Validation
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