This is a test file uploaded to your S3 bucket to see if it's configured properly.
If you can read this file it means that anyone can write to your bucket. Not only write but probably also delete or encrypt or modify your contents.

This is a friendly information to change permissions asap. 

If you want to discuss or say thank you, feel free to contact me on twitter: @secuninja
or have a look at my profile at openbugbounty.org https://www.openbugbounty.org/researchers/SecuNinja/


Secuninja

Making the web safer!