The author explains a P4 (proactive security) vulnerability involving improperly controlled caching on web applications.
This vulnerability can lead to many security issues such as unauthorized access and data leakage.
The first step in identifying this vulnerability is to check the cache control headers returned by the server through tools like curl or browser developer tools.
If the server does not include caching restrictions, the webpage may be cached by intermediary servers, potentially exposing sensitive data.
To demonstrate this, the author uses an example target of apps.target.com/accounts, where improper caching can lead to user data being exposed.
Thus, caching restrictions should be carefully set to only cache non-sensitive data, and not cache sensitive data, and authenticated sessions, preventing potential security issues.