Apple engineering mistake exposes clear-text passwords for Lion

An attacker could potentially decrypt information secured with an older version of FileVault, Apple's encryption technology
  • Jeremy Kirk (IDG News Service)
  • — 07 May, 2012 11:47

Apple's latest update to OS X contains a dangerous programming error that reveals the passwords for material stored in the first version of FileVault, the company's encryption technology, a software consultant said.

David I. Emery wrote on Cryptome that a debugging switch inadvertently left on in the current release of Lion, version 10.7.3, records in clear text the password needed to open the folder encrypted by the older version of FileVault.

Users who are vulnerable are those who upgraded to Lion but are using the older version of FileVault. The debug switch will record the Lion passwords for anyone who has logged in since the upgrade to version 10.7.3, released in early February.

"This is what the secure FileVault partition was supposed to protect against after all," Emery said in an interview.

Apple has two versions of FileVault. The first version allowed a user to encrypt the contents of the home folder using the Advanced Encryption Standard (AES) with 128-bit keys. An upgraded product, FileVault 2, which shipped with OS X Lion, encrypts the entire content of the hard drive.

When someone upgrades to Lion but still uses the first version of FileVault, the encrypted home folder is migrated, which is now vulnerable with this security issue. Emery wrote that the password is accessible to anyone with root or administrator access, he wrote. But what is worse is that passwords can also be read another way.

Emery described that passwords can also be read by "booting the machine into FireWire disk mode and reading it by opening the drive as a disk or by booting the new-with-Lion recovery partition and using the available superuser shell to mount the main file system partition and read the file."

"This would allow someone to break into encrypted partitions on machines they did not have any idea of any login passwords for," he wrote.

There are a couple ways to mitigate the problem. Emery wrote that the FireWire disk and recovery partition attack can be headed off by using FileVault 2. An attacker would have to know at least one password before a file could be accessed on the main partition of the disk, he wrote.

Also, a firmware password could be set that would be needed in order to boot the recovery partition, external media or even enter the FireWire disk mode. Emery cautioned though that Apple "Genius Bar" employees know a standard technique to turn it off.

The issue highlights the fragility of technology, Emery said. "A mistake like this exposes more or less the keys to the kingdom to someone with literally no access to a supposedly secured area on a machine, and maybe nothing more than chance physical access to a target's laptop for a few unguarded minutes," he said.

The bug has probably been around since the release of 10.7.3, Emery wrote. Emery said he wasn't the first to find the problem, and that other people discovered it several weeks before he did and reported it to Apple.

"One wonders why such a debug switch exists in shipped production code," Emery wrote. "Clearly it could be invoked covertly in specific situations. This seems to be an example of someone turning it on for the entire release by accident."

Apple did not have an immediate comment.

Send news tips and comments to jeremy_kirk@idg.com

Reverse Heartbleed puts your PC and devices at risk of OpenSSL attack

READ THIS ARTICLE
DO NOT SHOW THIS BOX AGAIN [ x ]
Comments are now closed.
CSO Corporate Partners
  • Webroot
  • Trend Micro
  • NetIQ
rhs_login_lockGet exclusive access to CSO, invitation only events, reports & analysis.
CSO Directory

Enterprise Security for Endpoints

Think your endpoints are secure? Think again. Learn why Trend Micro can help.

Latest Jobs
Security Awareness Tip

Incident handling is a vast topic, but here are a few tips for you to consider in your incident response. I hope you never have to use them, but the odds are at some point you will and I hope being ready saves you pain (or your job!).


  1. Have an incident response plan.

  2. Pre-define your incident response team 

  3. Define your approach: watch and learn or contain and recover.

  4. Pre-distribute call cards.

  5. Forensic and incident response data capture.

  6. Get your users on-side.

  7. Know how to report crimes and engage law enforcement. 

  8. Practice makes perfect.

For the full breakdown on this article

Security ABC Guides

Warning: Tips for secure mobile holiday shopping

I’m dating myself, but I remember when holiday shopping involved pouring through ads in the Sunday paper, placing actual phone calls from tethered land lines to research product stock and availability, and actually driving places to pick things up. Now, holiday shoppers can do all of that from a smartphone or tablet in a few seconds, but there are some security pitfalls to be aware of.