Java Snippet #11
This challenge covers the review of a snippet of code written in Java
The Code Review Snippet challenges provide small snippets of vulnerable code, and in this lab, we focus on Fetcher.java. The code is designed to fetch content from a specific URL but uses a regular expression to validate the URL. However, the regular expression is flawed because the dots in the domain are not escaped, allowing any character to replace them. As a result, someone could easily bypass the filter by registering a similar domain like secureApentesterlab.com.
The lab guides you through the code, explaining each step, from importing libraries to handling exceptions. The primary issue is that the code's regular expression (Pattern.compile("^https://secure.pentesterlab.com/")) does not properly escape dots, making it vulnerable. This oversight allows attackers to exploit the regex and potentially access restricted URLs.