SSRF vulnerability on Google's Feedburner

Feb 10, 2016 • bugbounty

SSRF bug in Google's feedburner.

Recently after getting an SSRF on Microsoft’s Bing Webmaster central, I decided to test the same attack on any of the Google acquisitions and feedburner was a great choice. So I quickly went ahead to test the site and I saw an option to add new feed from a URL. Let’s try injecting port numbers into it and see what happens:

As usual, I entered the url and to my surprise, I got back a result saying: Received HTTP error code -1 while fetching source feed. Well, it looks like this is vulnerable to SSRF. Let’s confirm it by trying with a closed port; so this time I changed the port number from 22 to 25, which is a closed port, I got another error saying: An error occurred connecting to the URL: unknown error. Well, I guess the vulnerability is confirmed now. I got 2 different errors depending on whether the port number is closed or not.

I tried to expand this by trying to scan the internal networks but unfortunately I had no luck there. Then I tried using other protocols like file:// but this was also restricted. Only http:// or https:// can be used. Sadly I reported the bug to Google hoping that they will atleast fix it but won’t reward since it’s a low priority bug. The reply they gave was: The ability to scan a port is not in itself a vulnerability. It seems they have already explained about this on their bug hunters university

Even through Google said that this is not a vulnerability, at a later point of time I saw that this issue has been being fixed. And as of now, no matter what port number you give, it always returns the error: An error occurred connecting to the URL: internal error. Looks like they patched the vulnerability but didn’t give any credits for it.

Anirudh Anand

Security Engineer @CRED | Web Application Security ♥ | Google, Microsoft, Zendesk, Gitlab Hall of Fames | Blogger | CTF lover - @teambi0s | Certs - eWDP, OSCP