User ID controlled by request parameter

In the intricate world of cybersecurity, access control flaws can lead to catastrophic breaches. One such silent but deadly vulnerability is allowing User ID to be controlled via request parameters. Often overlooked, this vulnerability can be exploited to gain unauthorized access to sensitive user accounts, leading to data theft, privilege escalation, or even full system compromise.

Let’s dive into why this vulnerability is so dangerous, how it works, and most importantly, how to avoid it.

Many web applications use URL or request parameters to identify the current user and their data. For instance, a typical URL might look something like this:

https://example.com/profile?user_id=123

Here, the user_id is a request parameter that identifies the user. When a web application directly relies on this parameter without proper validation, an attacker can simply change the value of user_id to access another user’s profile or account. This type of vulnerability is known as Insecure Direct Object Reference (IDOR), and it's a part of the broader category of access control issues.