I really love the Gravatar concept. Its simple, useful, powerful and centrally managed, but how secure is it to use on a blog or service?
Regular users may have already seen that we have implemented Gravatars onto BlogSecurity; so its safe to use then, right?
I made a point on our new BlogSec-News service a couple days ago when implementing Gravatars onto BlogSec. This article expands these points.
My first thought was, creating a malicious image link and posting this on Gravatar. Imagine placing a malicious peice of code as your profile picture. Every site that has approved your previous comments are all of a sudden vulnerable! However, this thought was quickly exhausted, as Gravatar does not permit third party links. All images are uploaded to Gravatar and centrally managed. Good move!
So what are the risks then?
Without looking at the service in great detail, there are two obvious risks with using this service, both of which you should understand and accept before using it.
Firstly and less likely: If the Gravatar servers are hacked, attackers could embed malicious code into links, which could be used in a variety of attacks including Denial of Service and may, although unlikely, lead to your blog being compromised. However, for this to happen, your site would have to be vulnerable to other attacks.
Second and more likely: Users control what rating their images receive. By accepting Gravatars, you accept the possibility that some users may use inappropriate images or images of a sensitive nature. Its also difficult to detect these images, unless you were monitoring every post comment on every post (impossible). The end result may be an unhappy user or visitor who blames your site, especially when they fail to understand how the Gravatar service work.
It is important that these risks are understood and accepted before using the service. As a community, hopefully we’ll look out for these images. When spotted, we could always inform Gravatar, who hopefully have a procedure in place to manage abuse.
