Lately, I have been noticing a lot of blogs about CASB Reverse Proxy being used to route the traffic of a cloud application to improve security by parsing the traffic and applying various conditions to evaluate its risks.
I couldn't find any technical explanation related to this.
How can a cloud application like Office 365 or GSuite route its traffic through a proxy server? I do not see any configuration for this in these apps.
Assuming, I configure the proxy to point to a cloud application like Microsoft Teams. Whenever I access the proxy url, it proxies everything to Microsoft Teams. In my Reverse Proxy, I either get the url being accessed or the HTML content of the page being loaded. How can these be used to evaluate security risks? I couldn't find any docs in Office 365 or Gsuite regarding this.
Are there any APIs provided by Office 365 for this? I also checked Microsoft Graph Security API but it looks like those APIs give data about actions already completed and not the ongoing action which is what a reverse proxy is for..
PS: I'm not looking at any specific vendor. I'm just trying to learn the technical concepts. Any answers in context of Office 365 or Gsuite is appreciated because I have only those accounts and not any other cloud application.