It has come to the IT administrator's attention that the "post your comment" field on the company blog page has been exploited, resulting in cross-site scripting attacks against customers reading…

HTTPS encrypts data in transit between client and server but has no effect on the content of user-submitted input; a malicious script submitted over HTTPS is just as dangerous as one submitted over HTTP.

XSS attacks depend on injecting metacharacters such as '<', '>', '"', and '&' to break out of the text context and introduce executable HTML or JavaScript. Filtering or encoding these characters on the server side before storing or rendering user input neutralizes the attack vector at its source, preventing malicious scripts from ever reaching other users' browsers.

A host-based intrusion detection system monitors OS-level events and file integrity on the server but does not inspect or sanitize web application input fields.

Patching the web application is a valid general practice but is too vague to be the most effective specific control; the root cause is unsanitized input, not an unpatched software vulnerability.

Client-side input validation can be trivially bypassed by an attacker using browser developer tools or a proxy, so it provides no real security guarantee and must not be relied upon as a sole defense.