PHP Snippet #06
This challenge covers the review of a snippet of code written in PHP
The Code Review Snippet challenges are designed to help you identify vulnerabilities in a small piece of code. This particular challenge involves a mix of HTML and PHP, where an 'a' tag is created with an 'href' attribute containing a PHP echo statement. The issue lies in the improper encoding of single quotes by the htmlentities() function, which can be exploited by an attacker to inject malicious attributes like onClick or onMouseOver into the 'a' tag.
In the video, we discuss how htmlentities() encodes several characters to HTML entities but does not encode single quotes by default. This oversight allows an attacker to manipulate the 'href' attribute by inserting a single quote in their username. To mitigate this vulnerability, developers should either use double quotes in the 'href' attribute or add the ENT_QUOTES flag to htmlentities() to ensure single quotes are also encoded.