PHPPwner3000 is the ultimate PHP exploit tool. Utilizing fundamental vulnerabilities in ALL versions of PHP, it is able to upload files, query databases, and even slurp shadow files no matter what user php is running as. Using stealth sql injection, it can even bypass the protections provided by prepare/execute structures.
PHPPwner3000 is also completely fictitious. It is a honeypot entry in a job posting. I use it to determine if a candidate does sufficient recon and is capable of going the extra mile when they see a term with which they are unfamiliar.
If you have found this page because you saw an unfamiliar tool in a job posting, congratulations. You've just earned brownie points with one of the interviewers. It's up to you to figure out which one.