Privacy News TLS Certs Outliving Domain Ownership Open Door to MitM and DoS

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Content source

https://www.bleepingcomputer.com/news/security/tls-certs-outliving-domain-ownership-open-door-to-mitm-and-dos/

Digital certificates that allow secure data exchange over the internet can survive domain ownership transfer and can open the door for malicious actions to the previous holder.

An SSL/TLS certificate relies on the public key infrastructure (PKI) model to ensure that information flows securely online. The way this works is that web servers establish a trusted connection with the client browser by presenting the digital certificate. After server authentication, the connection with the client is encrypted and sensitive information can pass through.

A couple of security researchers, Ian Foster and Dylan Ayrey, found that the validity of these certificates in some cases extends beyond the registration period of a domain. When a new owner registers the domain, the initial proprietor still holds the SSL certificate associated with it.

Used certificates come with serious risks

One of the risks is that of a man-in-the-middle (MitM) attack, where a valid SSL certificate for the domain would decrypt the communication between the web server and the client.

Another possibility is denial-of-service (DoS) when additional domain names are defined under the same certificate as subject alternative names. When an alternative site is no longer owned by the certificate user (also referred to as a “bygone domain”), “it is possible to revoke the certificate that has both the vulnerable alt-name and other domains. You can DoS the service if the shared certificate is still in use,” explain the researchers.

Checking the history of a certificate was not possible before the Certificate Transparency (CT) project launched in 2013. CT is a public framework that logs all certificates issued by public Certificate Authorities. Its database holds in excess of half a billion certificates and keeps on growing.