Cloudflare has announced the Cloudflare PHP Capture the Flag challenge, a hands-on exercise that lets participants test the company's web application firewall (WAF) against realistic PHP-based attack scenarios. The launch follows a turbulent week in Internet security history that shaped the challenge's focus.
That week began with the compromise of eight eMudhra intermediate certificates, raising the possibility of forged certificates used to impersonate servers. It was followed by php2shell, a set of serious vulnerabilities in PHP, the runtime powering a large share of the Web. Cloudflare responded around the clock to protect customers, shipping client updates, rolling out multiple mitigations, and adding new WAF rules to block exploitation of the PHP flaws.
Key points from the announcement:
- Cloudflare introduced a feature called full transaction detection during the incident response.
- These new capabilities were made available on all plans, including Free.
- The WAF was updated with new rules targeting the php2shell vulnerabilities.
- The new PHP Capture the Flag challenge is now open, run through Cloudflare's platform.
- The challenge is framed around collecting real-world data to test assumptions and strengthen defenses.
Cloudflare stresses that protecting systems from vulnerabilities is an ongoing process rather than a one-time event. The company notes that widespread adoption of AI lets attackers discover new vectors with unprecedented speed and efficiency, making real-world testing data essential.
For developers, the challenge is a practical opportunity to see how a production WAF handles PHP attack patterns and to understand the defenses that now ship by default on every plan, including Free. It also highlights the value of continuous adversarial testing as AI accelerates the pace of vulnerability discovery. Testing your own assumptions against real attacks is increasingly part of responsible application security, and Cloudflare is positioning the CTF as a way to contribute data that hardens defenses for everyone.