FYI: FileVault and Security Update 2004-09-07 Bug

Posted:
in Genius Bar edited January 2014
This is both a posting of a FileVault bug and the work-around for it.



After installing the latest security update, upon reboot and login to the main account for the machine [10.3.5] I discovered that my account was *gone*--as in, it might as well have been a clean install.



Ouch.



To make the story short, I think I figured out what went wrong. FileVault had been on [and still was]--which was scary, as I was afraid that since it was on, that it had replaced the actual image. Luckily, this was not the case:



Located at /Users/$USER/$USER.sparseimage was the actual FileVault image [where $USER is the account-name]. On a whim I double-clicked it and found that I could mount it as a regular image, though password protected.



The trick is: the password for the image was the ORIGINAL password used when it was created and not the account password. When you turn on FileVault, these are [and must be] one and the same--changing the account password seems to allow these to fall out-of-synch.



So, this was the first update since I changed the passwords for this account [and root]--and it appears that it was simply unable to authenticate to the FileVault image.



THE FIX [not all of these steps may be necesary, this is merely how I got around it]:

Mount the image using your original password.

Copy the contents to a root-accessible location.

Turn off FileVault for the user.

Rename the FileVault image [just being cautious].

Log out.

Log in as root.

Copy the contents of the image over that user's directory.

Log out.

Log in as user--everything should be back.

Turn FileVault on.

[one should then root-ify and secure wipe the archived files et alia].



[EDIT]: when copying, be sure to copy the hidden directories as well (turn them on in the UI or use command line "cp -prv " or such) -- otherwise, you may lose your .ssh, .gpg, .shell configurations :[EDIT]



Since then, I've also noticed that KeyChain is also using the original password, and not the current one for the account.



Conclusions: Somebody at Apple was *smart* to have it FileVault not replace a user's image when one isn't available [like in this situation] and FileVault is still on [running from a 2nd image, I suppose].



KeyChain and [if separate] FileVault do *NOT* get updated automatically when a user changes their password. If this is the case, this is *BAD*, as it leaves a back-door when passwords are updated [in the case that a password is compromised, such as when an employee leaves a company].
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