Alex Ivkin, Senior IT Security Architect
OpenID is an identity sharing and a single sign on protocol, that is becoming more and more popular on the net. OpenID allows us to use a single authenticating source (aka an identity provider) to login into any site that accepts OpenIDs (aka a service provider) without the need to create an account on that site. Yahoo!, Google, AOL, SourceForge, Facebook and many others now support it now. A great idea, but unfortunately it comes with some big holes.
What OpenID means, in an essence, is that you are entrusting all your account accesses to a single source. You trust your identity provider to safeguard your personal information until you decide to use it. So, to no surprise, most of the attack vectors are targeting this trust relationship.
Spoofing an identity provider
If you use one of the common identity providers, say myopenid.com, you need to be aware of identity phishers. An attacker could devise a site, that, after asking you to login with an OpenID, sends you to a myopenid-look-a-like.com. You, trustingly, enter your OpenID login information, and, boom, your id and your password that opens access to all you OpenID accounts are in the wrong hands.
The switch user attack
If you are one of the paranoid types and host your own identity provider, say via a Wordpress OpenID plugin, you may succumb to a URL hijacking technique. If attackers gain an ability to modify pages on your site (PHP is great at that), they then could modify the headers on your pages to redirect openid validation requests to their own identity provider. With the redirect configured, when they log in into a service provider with your OpenID URL, the service provider will authenticate against attackers’ own identity provider, thus making them appear as you, anywhere they go. We’ve proven this scenario on our host, and it is very viable and very scary.
OpenID URL hijacking
Another set of attacks targets the OpenID URL. An Open ID URL is your unique identifier on the net to the service providers. If someone gains control over the URL, either due to DNS manipulation (google DNS attacks) or site hacking, they have a key to all your accounts. An example would be to trick a service provider into resolving your OpenID URL to an attacker’s site that uses attacker’s identity provider, thus making the service provider trust an attacker, posing under the URL of the victim. The use of i-Numbers in lieu of URL’s is supposed to help with this issue, but they are not yet widely supported.
Cross site request forgeries
OpenID does not validate all of the traffic going between the identity provider and service provider in a user browser via hidden i-frames. A malicious site could supply your browser could with a page that, knowing your openid from the cookies, could determine your identity provider name and automate actions to any number of service providers, acting on your behalf. The actions could range from creating accounts under your name to divulging details of your existing accounts on these sites. Secunia provided detailed research on this type of the XSS.
OpenID sign on process makes it really easy for automated processes to login or create accounts on the fly. A spammer could create an identity provider validating its own id’s at a rate of hundreds a second and then supply them to the service providers. This could be mitigated by pairing an openid field with a captcha field, but it is not supported by most OpenID service providers right now.
Yes, there are bugs, both in the specifications and the technical implementations. I would not go in to details here, since these are typically short lived and are addressed by the vendors in an on-going basis. The holes are exploited by the hackers and are expected for any new technology appearing on the web. The problem is that the stake with OpenID is a lot higher. Loosing an OpenID means not only losing your ID but also losing a multitude of accounts and associated personal information.
OpenID keeps your ID off your hands and on the net, the place that you have no control over. I am sure, current OpenID providers will work hard to make sure they are well protected to retain your trust, but rest assured, there will be breaches. Identity provides are very attractive targets to hackers, since they act as gateways to a wide array of accounts. And when this happens all your accounts are potentially lost, not just one. Thus, OpenID should be treated as a convenience, not a way to increase security of your accounts. From another perspective, assuming Linus’ law holds, I do not see OpenID going the Microsoft Passport way. OpenID has its advantage in being open and freely available.
Nonetheless, until OpenID is mature from the security prospective, like SSL and GPG, I am sticking with managing my accounts in an encrypted web browser’s password store. It’s almost as convenient and a lot better protected. After all, you keep your driver’s license in your own wallet, not posted on the web.
Alex Ivkin is a senior IT Security Architect with a focus in Identity and Access Management at Prolifics. Mr. Ivkin has worked with executive stakeholders in large and small organizations to help drive security initiatives. He has helped companies succeed in attaining regulatory compliance, improving business operations and securing enterprise infrastructure. Mr. Ivkin has achieved the highest levels of certification with several major Identity Management vendors and holds the CISSP designation. He is also a speaker at various conferences and an active member of several user communities.