We have previously talked about LinkedIn having an endpoint for Outlook profile cards. This endpoint is receiving email addresses as input and returns the complete profile information (name, company, location, etc.). These sorts of APIs can be abused for OSINT.
To reproduce the set-by-step tutorial your will need an Outlook account (@hotmail.com, @live.com or outlook.com email), the latest version of ZAP and our WebSocket plugin.
When we were looking at the interactions between the Outlook and the LinkedIn APIs, we encountered WebSocket communications that used some additional encoding. The encoding was nothing too complex, but it was uncommon. It turned out to be LZip compression. However, the inability to read the content of the requests with Burp, ZAP or Web developer consoles in real-time made it difficult to analyze the API.
In this blog post, we will look at the privacy issues with some of LinkedIn’s external APIs. We will demonstrate how it is possible, with an email address, to find its associated LinkedIn profile. It is also possible from a LinkedIn profile to do the reverse path and find a person’s email address. To execute this deanonymization attack, documented features, like LinkedIn’s integration with Outlook and YahooMail, are used.
If you are testing the security of WordPress websites, you will likely have to look at the REST endpoints. By default, users can be listed with the route “/wp-json/wp/v2/users”. On the latest WordPress version, out of the box, you will get the username and the hashed email. Experienced WordPress administrators and users are aware of the potential disclosure. Therefore, we can see various tutorials online on how to hide this information. The recommended ways are either to disable the REST API completely, install a security plugin which disables the specific route or block specific request paths.