security

There are many articles that cover PHP vulnerabilities, but I've run across a lot of programmers and code that seems oblivious to them. When interviewing programmers, I look for an understanding of these types of vulnerabilities, and how to prevent their programs from being vulnerable to them.

Aside from register globals issues, most of these attacks are not specific to PHP.

Register Globals issues
From early on, the developers of PHP had this great idea: accept any parameters passed from the browser, and automatically turn them into variables available in the code.