TL;DR Bucket upload policies are a convenient way to upload data to a bucket directly from the client. Going through the rules in upload policies and the logic related to some file-access scenarios we show how full bucket object listings were exposed with the ability to also modify or delete existing files in the bucket.

Last year we exhibited at a major information security trade show in London, during the preparation for this we received our exhibitor passes as “print yourself” PDF files. We immediately noticed that there are two forms of barcode here and, interestingly, the QR Code seems quite dense given that all it should be storing is a delegate ID number. Being the inquisitive sort of people that we are, we started up a QR scanner and had a look at its contents.