Open redirection vulnerabilities occur when an application unsafely incorporates user-controllable data into a redirection target. Attackers can exploit this to redirect users to arbitrary external domains, facilitating phishing attacks. The use of a legitimate application URL and valid SSL certificate adds credibility to the phishing attempt, as many users may not notice the redirection to a different domain.
Validate and restrict user inputs for redirection targets, allowing only a predefined list of trusted URLs. Avoid using user-supplied data directly in redirection functions, and implement security mechanisms to detect and prevent open redirection attempts.