Most people don’t give much thought to what happens when you connect to your bank’s website or log in to your email account. For most people, securely connecting to a website seems as simple as checking to make sure the little padlock in the address bar is present. However, in the background there are many different steps that are taken to ensure you are safely and securely connecting to the websites that claim they are who they are. This process includes certificate validation, or making sure that the servers that users are connecting to present “identification” showing they are legitimate. This helps to protect users from fraudulent servers that might otherwise steal sensitive information.
Due to the sensitive nature of this process, software vulnerabilities that adversely impact the security of certificate validation could have major consequences. Unfortunately, digital systems are complex and bugs are an inevitable reality in software development. Identifying vulnerabilities and responsibly disclosing them improves the security of the internet by eliminating potential attack vectors. Talos is committed to improving the overall security of the internet and today we are disclosing TALOS-2017-0296 (CVE-2017-2485), a remote code execution vulnerability in the X.509 certificate validation functionality of Apple macOS and iOS. This vulnerability has been responsibly disclosed to Apple and software updates have been released that address this issue for both macOS and iOS.