As browser developers try to push the industry toward safer certificate standards, it won't come without some pain: Tens of thousands of sites are already experiencing that following a move last week by Mozilla to revoke a number of root certificates using 1024-bit keys. According to security researchers, that's the approximate number of sites left untrusted as a result of Mozilla's not-so-subtle push to get developers to upgrade their SSL protections with certificates utilizing 2048-bit keys.
According to Mozilla, the company is forcing migration away from 1024-bit certificate in phases, so at the moment it has only revoked select certificates from Entrust, SECOM, GoDaddy, EMC/RSA, Symantec/VeriSign, and NetLock. It will wait until early 2015 to revoke similar certificates from Thawte, VeriSign, Equifax, and GTE Cybertrust that are operated by Symantec and Verizon Certificate Services. "We are actively working with CAs to retire SSL and Code Signing certificates that have 1024-bit RSA keys in an effort to make the upgrade as orderly as possible, and to avoid having system administrators find themselves in emergency mode because their SSL keys were compromised," says Kathleen Wilson of Mozilla's security engineering team.
However, according to data gathered from HD Moore's Project Sonar internet scanning data collection at Rapid7, the current revocation leaves approximately 107,535 sites in an untrusted state. That may seem bad at first blush, but many of those certificates were already long expired or recently expired in July or August.
"The repeal of trust for these certificates is a sound decision based upon NIST recommendations, and while it initially appeared that a great many sites would be affected, the majority of these sites either have expired certificates or a certificate that expires within the next year," says Jody Nickel, senior platform engineer at Rapid7. "We hope that Chrome and other browsers will also remove these certificates to remove the potential risk involved with these 1024-bit CA keys."
Google is actually on a similar mission as Mozilla to remove potentially insecure certificates. Last week the firm announced plans for gradually sunsetting certificate chains using the SHA-1 encryption algorithm. It'll start with the next release of Chrome 39 at the end of this month and continue through two more releases until first quarter of 2015. The firm points to guidance from both the CA Browser Forum and NIST in the deprecation of SHA-1 as its reasoning for the shift.
"We have seen this type of weakness turn into a practical attack before, with the MD5 hash algorithm," say Chris Palmer and Ryan Sleevi of Google. "We need to ensure that by the time an attack against SHA-1 is demonstrated publicly, the web has already moved away from it."