HexBrain

Imgur · Report #105463

risk of having secure=false in a crossdomain.xml

Validstatus
3upvotes
3 Mar 2016disclosed

How it was found

api.imgur.com permits SWF files on a non-HTTPS server to load data from this HTTPS server. Setting the secure attribute to false could compromise the security offered by HTTPS. In particular, setting this attribute to false opens secure content to snooping and spoofing attacks.

The allow-access-from node has an optional attribute 'secure'. So say the crossdomain.xml on api.imgur.com has :

<allow-access-from domain="imgur.com" secure="false"/> <allow-access-from domain="*.imgur.com" secure="false"/> <allow-access-from domain="*.imgur-dev.com" secure="false"/>

If this is set to true (default), a flash client retrieved over HTTP cannot access data on the ideanetsetter.yahoo.com over HTTPS.

I can only think of one risk in setting secure to false: A user with a poisoned host file or DNS server might be diverted to a flash client on a fake http://subdomain.example.com. This flash client can now access sensitive data on api.imgur.com

Good Fix ,

This report was disclosed publicly on HackerOne and belongs to its author and the program. See the original