Ruby Snippet #06
This challenge covers the review of a snippet of code written in Ruby
The Code Review Snippet challenges at PentesterLab are designed to enhance your skills in identifying vulnerabilities in small snippets of code. In this lab, you will examine a Ruby-on-Rails application and identify the security flaw without initially referring to the provided video. The given code consists of a controller and a model, where the controller processes an email recipient parameter and the model sends an email.
Upon reviewing the code, it becomes apparent that there is a vulnerability in the handling of the recipient parameter. The regular expression used to validate the email allows for multi-line input by default in Ruby on Rails, which can be exploited to inject arbitrary commands. This vulnerability can lead to command execution due to improper handling of the recipient value in the command line.
To mitigate this issue, developers should replace the ^ and $ with \A and \z respectively to accurately match the start and end of the string, rather than the start and end of a line. This adjustment ensures that the input is properly validated, preventing injection attacks. It's crucial to be aware of this behavior in Ruby applications and always validate regular expressions accordingly.