On Sept. 1, browsers and devices from Apple, Google, and Mozilla will show errors for new TLS certificates with a life span longer than 398 days. The move, while beneficial for security, pushes back against certificate authorities (CAs) and may prove an operational headache for businesses.
The life span of SSL/TLS certificates has dramatically shrunk in the past 10 years. Just over a decade ago, domain registrars sold TLS certificates valid for eight to 10 years. The Certification Authority Browser Forum (CA/Browser Forum), a group of CAs, imposed a five-year limit in 2011. This was cut to three years in 2015 and to two years in 2018.
Historically, these changes were made in collaboration between browser makers and CAs, with the two parties debating rules and changes before voting on and implementing them – until a ballot proposing one-year validity was voted down by CAs at a CA/Browser Forum meeting. Following this, Apple broke standard processes and individually chose to enforce 398-day limits in Safari.
Apple made its decision public in February and confirmed this change will only affect TLS server certificates issued from Root CAs on or after Sept. 1. Certificates issued before then won’t be affected; neither will those from user-added or administrator-added Root CAs. Mozilla and Google have voiced plans to implement a similar rule in their browsers starting on Sept. 1.
The change will have consequences: Apple says connections to TLS servers violating its new requirements will fail, which may cause network and applications to fail and prevent websites from loading. Google warns certificates older than 398 days will be rejected with an error and treated as misissued. Apple recommends new certificates be issued with a 397-day validity.
Browser makers have long argued that shorter TLS life spans are better for browser security because they reduce the time frame in which attackers could compromise or duplicate a certificate, which is critical to protecting traffic to and from websites. A successful attack would give someone “the keys to the kingdom,” says Lamont Orange, CISO at Netskope. As attackers look to move higher up the food chain, he says, this is precisely what they want.
“This is better than username and password in a lot of ways,” says Orange, of this level of compromise. Credentials may grant access to a system that could enable lateral movement across the environment. Access to a certificate could let an attacker do far more nefarious activities: control Web properties, access desktops and laptops, or encrypt communications.