With nothing more than a laptop, the group was able to steal credentials and eavesdrop on certificate authorities. “We evaluated the attack against a number of CAs and we set up a live (automated) demo against one CA,” said Dr. Haya Shulman, head of the cyber security, analytics and defenses division at the Fraunhofer Institute for Secure Information Technology.
“Essentially, many CAs that support domain validation can be attacked. We demonstrated an attack which redirects the CA to an attacker machine via DNS cache poisoning,” Shulman said.
“But, other techniques can be applied, such as BGP prefix hijack. Indeed, such attacks are common and only recently MyEtherWallet users were attacked via BGP prefix hijack that was then exploited for DNS cache poisoning. Essentially this means that such attacks are happening and an important security mechanism such as the web PKI should be protected against such practical attacks.”
Researchers will present their findings, which name the affected Certificate Authorities (CAs), at the ACM’s Conference on Computer and Communications Security in Toronto on October 15-19, 2018. The goal of sharing the research is not to guard only against their attack findings but to harden the PKI against off-path attackers and to make it secure against man-in-the-middle (MitM) attackers.
“While this attack is relatively complex to pull off, it demonstrates a fundamental problem with Domain Validated (DV) certificates. DV-issued certificates offer the lowest level of identity validation, sacrificing solid identity proof in exchange for speed and automation,” said Justin Hansen, security architect at Venafi.
“The impact of this attack can be quite serious because if an attacker can successfully poison DNS for any domains owned by a targeted organization, they will be able to get a certificate for that organization, and everyone on the internet will trust it. The attacker can then do a whole range of malicious things with that domain.”
Because these types of compromises can occur, Hansen said that organizations should explore higher assurance certificates such as Organization Validation (OV) and Extended Validation (EV).
“As we also argue in the paper, certificate authorities that support Domain Validation (DV) control more than 95% of certificates market,” Shulman said.
“The reason is that the process is faster, cheaper and easier (it is mostly automated). The OV and EV certificates take long to issue, are cumbersome and more expensive (which is why most domains do not use them). It also would not completely mitigate the security issue. Essentially we recommend deploying DV.”