The purpose of the Keychain is to hold on to various login credentials and other secretive information and to keep it hidden from prying eyes. Like third-party password managers, you’re only supposed to be able to access that information with a master password. With the bug in High Sierra though, it appears that unsigned apps are able to circumvent that safeguard entirely.
Discovered by ex-NSA analyst and security researcher Patrick Wardle (thanks MacRumors), the bug makes it possible to dump the contents of Keychain’s password storage, accessing everything from banking passwords, to your Facebook login in plaintext.
Perhaps even more concerning is that this bug may have existed for some time. Although it has been proven to work following the High Sierra update, it’s possible that it could also work with older versions of MacOS.
The one silver lining to this news is that, as with many attacks from nefarious individuals, a High Sierra user would need to download a malicious application from somewhere other than the App Store for the exploit to work. That’s something that Apple and most security professionals would heavily discourage, though it does sometimes happen.
To prove that the exploit exists, Wardle crafted a malicious app called “KeychainStealer,” which was able to reveal his phony Bank of America, Twitter, and Facebook login details with little effort. Although he hasn’t revealed the exact method of attack, it stands to reason that if he can figure it out, others will be able to as well, especially now that they know it’s possible.
For that reason some may not like that Wardle has been transparent with his concerns, though this story stands a much greater chance of forcing Apple to fix the bug than if he’d kept it to himself.
Still, it’s possible that this announcement isn’t entirely altruistic. Wardle does operate a Patreon to help support the creation of security software under his Objective-See brand, so this announcement should drive some interest in it.
