Python Snippet #03
This challenge covers the review of a snippet of code written in Python
The Code Review Snippet challenge provides a small snippet of vulnerable Python code for participants to analyze. The server script imports essential libraries and handles HTTP GET requests by processing cookies. A critical flaw lies in the use of the pickle.loads function on user-supplied data, which can lead to arbitrary code execution if an attacker sends a malicious pickle object. Additionally, the username is directly inserted into the HTML response without proper escaping, making the application susceptible to cross-site scripting (XSS) attacks.
In the provided script, cookies are parsed to retrieve the username value, which is then base64 decoded and deserialized using the pickle module. If the cookie is absent, a default username of "stranger" is used. The server responds with a simple HTML page displaying a greeting message. However, the lack of input validation and proper escaping creates significant security risks. The video accompanying the challenge explains these vulnerabilities in detail, emphasizing the importance of secure coding practices to prevent such issues.