ModSecurity: investigate blocked requests without disabling the firewall

ModSecurity is a web application firewall layer that can inspect requests before the application processes them. A blocked submission may be a genuine attack or a false positive; the response code alone does not establish which.

Investigate one failure

1. Record the affected domain, URL, time and operation. Use non-sensitive sample content to reproduce where possible.
2. Check application logs and the response. Ask support to inspect the firewall event and rule identifier.
3. Review whether the request contains unexpected HTML, executable content or malformed parameters.
4. If the request is legitimate, ask for a narrowly scoped exception or application correction.
5. Retest the specific workflow and confirm protection remains active elsewhere.

Avoid a broad workaround

Disabling the firewall for every domain can expose unrelated sites. Increasing PHP limits or changing PHP versions will not resolve a rule match. Do not teach customers to bypass security checks simply to submit a form.

Avoid sending full payment details, passwords or private form contents in a ticket. A redacted request description and timestamp usually give support a safer starting point. Keep a record of any exception and review it when the application changes. A firewall complements patching and input validation; it does not replace them.