TweetFollow Us on Twitter

MacEnterprise: FileVault in the Enterprise, Part 2

Volume Number: 24 (2008)
Issue Number: 09
Column Tag: MacEnterprise

MacEnterprise: FileVault in the Enterprise, Part 2

Data security for OS X administrators

By Greg Neagle, MacEnterprise.org

Previously in MacTech

Data security is a hot topic in Enterprise IT these days. As laptop usage increases, pushing out traditional desktops, the risk to company data is greater than ever. If a laptop is stolen or lost, the replacement cost of the hardware may be a pittance compared to the value of the data stored on the laptop's hard drive.

Therefore many companies are mandating some sort of data encryption for company laptops. If a laptop is then stolen or lost, the data would be inaccessible to the thief. "Whole–disk encryption" is a direction many companies are moving toward, but as of this writing, there are no shipping products that will encrypt a Mac boot volume. So Mac administrators must work with what is available: a technology Apple calls "FileVault," which secures users' home directories with AES–128 encryption.

In part one of this series, we covered preparation and implementation of FileVault in an enterprise environment.

In this installment, we'll examine some of the issues you may encounter when implementing and supporting FileVault in an enterprise environment, and techniques and tools to use to deal with some of these issues.

Living with FileVault

Once encrypted, a FileVault–protected home directory is relatively transparent in operation to the user when he or she logs in. The main clue you'll see when using a FileVault–protected account is the FileVault icon replaces the "normal" home icon in the Finder.

It's important to realize that while the user is logged in, any other user that has access to the machine (either physically or over the network, say via SSH) and that has root or sudo privileges can still access the files in the user's home directory. This can be a good thing, or a bad thing, depending on your point of view. Only when the user is logged out are the files inaccessible, because the encrypted disk image is unmounted.


FileVault–protected home directory in the Users folder

This points out a security hole: what if a laptop is stolen while the user is logged in? In fact, this is a very likely scenario many users rarely log out or shut down; instead they simply put the machine to sleep by closing the lid. If a machine is stolen in such a state, the FileVault disk image is unencrypted and mounted, so the user's files are accessible.

To close this security hole, you'll want to enforce the Require password to wake this computer from sleep or screen saver setting found in the Security preference pane.


Security preference pane

This setting can be enforced using MCX policy. If a thief were to take a laptop configured in this manner, the password request would prevent them from accessing the logged–in user's files.

FileVault Issues

Some applications may behave poorly with FileVault–encrypted home directories. Some examples:

Final Draft 7 would crash at startup when launched from a FileVault–protected account; this was fixed in version 7.1.3:

http://media.finaldraft.com/downloads/readme_fd713.txt

  • Some Automator actions fail on FileVault–protected accounts:

    http://www.macosxhints.com/article.php?story=20051020203919140

    iMovie and GarageBand have known performance issues with FileVault home directories:

    http://docs.info.apple.com/article.html?artnum=93460

    http://docs.info.apple.com/article.html?artnum=42964

    http://docs.info.apple.com/article.html?artnum=93699

    http://docs.info.apple.com/article.html?artnum=93618

    http://docs.info.apple.com/article.html?path=GarageBand/4.0/en/6567.html

    FinalCut Pro and Express have performance issues as well:

    http://docs.info.apple.com/article.html?artnum=93454

    Other applications that need high–performance disk access may be similarly affected.

    There are certainly other applications that have issues. Be sure to test the important applications you use.

    In most cases, there are workarounds for the FileVault issues, but most of the workarounds open up data security issues once again, as they rely on moving data to a non–encrypted part of the disk. You'll need to decide how to handle this.

    Reclaiming unused space

    In 10.4 (Tiger), FileVault makes use of what Apple calls "Encrypted Sparse Disk Images"; the image files are very space–efficient. But as items are added and deleted, these image files can grow bigger than they need to be and some housekeeping must be done to recover unused space. If this is not done, eventually the disk image file will grow to fill all available hard drive space. Periodically at logout, the user is notified that the image is using more space than is needed and asks for permission to recover the unused space. If the user is in a hurry to shutdown, restart, or log back in, they can cancel this housekeeping task – but they shouldn't put it off forever! Depending on the size of the home directory and the amount of recoverable space, recovery can be quite fast, or take a very long time. Train your users to treat the computer with kid gloves during the space recovery – if they were to get impatient and turn off the computer or force a restart during the recovery process, they could corrupt the disk image, which could then lead to total loss of the home directory contents!

    With 10.5, the user experience is improved. FileVault now makes use of "sparsebundles", in which the disk image data is kept in a collection of files inside an enclosing directory. This revised format has several advantages, but the one relevant here is that unused space recovery is much, much faster. In fact, it's so fast that Apple no longer asks at logout if you want to reclaim unused space it just goes ahead and does it at each logout.

    A related issue: a user sees their hard drive is getting too full. They delete a bunch of files from their home directory and empty the trash. They are confused when there is no change in the available space on the hard drive. This is because the space is not reclaimed from the disk image file until logout (and, in Tiger, after the user agrees). Your support staff should be made aware of this issue, as it can cause much confusion.

    Recovering from a lost FileVault password

    If the user forgets their password, or changes their login password in a way that doesn't also update the FileVault password, they may find themselves locked out of their FileVault home directory. If you have the FileVault master password (and keychain), you can reset the password on the FileVault disk image.

    If password hints are turned on, after three unsuccessful attempts, a password hint will be shown, if one is set for the user's account. If there is no user password hint, or the user still enters an incorrect password, the login window will change, showing text directing the user (or an administrator) to enter the FileVault master password to reset the user's password and to unlock FileVault.

    In practice, I've found this to work only with purely local accounts protected with FileVault. Mobile accounts (those with Portable Home Directories) never show a password hint or the Master Password prompt, at least when testing in my environment. Fortunately, there is another way to unlock a FileVault–protected home directory: via the command line.

    Command–line FileVault Recovery

    Here's how to change the FileVault password from the command line. Log in as root, or with an account that has sudo privileges to act as root (Admin accounts by default on OS X have this ability). Watch the line breaks in the example below, all commands are entered as one single line:

    [mbp:~] gneagle% sudo security unlock–keychain /Library/Keychains/FileVaultMaster.keychain
    password to unlock /Library/Keychains/FileVaultMaster.keychain: 
    <enter FileVault master password>
    [mbp:~] gneagle% sudo hdiutil chpass /Users/someuser/someuser.sparseimage –recover /Library/Keychains/FileVaultMaster.keychain newstdinpass
    Enter new disk image passphrase:
    <enter your desired password>

    Be careful, as you are not prompted to confirm the new password. If you make a mistake, just run hdiutil chpass again.

    Leopard improvements

    A common scenario requiring the FileVault password to be changed is when the user changes their login password by some method other than the Mac OS X Accounts preference pane. For example, many organizations provide a web page to change network passwords. If a user changes their network account password in this manner, the FileVault password cannot be updated. The same issue occurs if the user uses multiple machines and changes their password on a machine other than the one with the FileVault–protected home directory.

    Under Tiger, this password mismatch almost always required administrator assistance to recover from. Leopard makes users' and administrators' lives easier in this regard: if a user authenticates at the login window with their correct network credentials, but the FileVault disk image cannot be unlocked with the current network password, the OS will now display a dialog asking the user to enter their previous login password. If the entered password can unlock the FileVault disk image, the disk image password is updated, and the user is able to login.

    Miscellaneous trivia

    You may have a need to determine if FileVault is turned on for a particular user of a machine. Since waiting for the user to step away from their machine so you can peek at the Security preferences pane while they are logged in isn't always practical, it's helpful to have another way.

    The most accurate way to determine if FileVault is enabled is to use dscl:

    [mbp:~] gneagle% dscl . read /Users/gneagle HomeDirectory
    HomeDirectory: <home_dir><url>file://localhost/Users/gneagle/gneagle.sparsebundle</url></home_dir>

    Note the file:// URL and the filename ending with ".sparsebundle" (or ".sparseimage" in Tiger). This is your proof positive that the account is using a FileVault–protected home directory.

    You might be a bit confused here. If the sparsebundle (or sparseimage) is stored inside /Users/username, how can it be made available at /Users/username when the user logs in?

    When the user is not logged in, the /Users directory looks something like this:

    [mbp:/Users] root# ls –al
    drwxr–xr–x    7 root    admin   238 May  2 16:01 .
    drwxrwxr–t   46 root    admin  1632 Apr 25 16:14 ..
    –rw–rr    1 root    wheel     0 Sep 23  2007 .localized
    drwxrwxrwt   24 root    wheel   816 Apr 30 14:46 Shared
    drwxrr  115 gneagle staff  3978 May  2 12:28 gneagle

    The gneagle.sparsebundle file is inside the gneagle directory. But once gneagle logs in, the /Users directory looks like this:

    [mbp:/Users] root# ls –al
    drwxr–xr–x    7 root    admin   238 May  2 16:01 .
    drwxrwxr–t   46 root    admin  1632 Apr 25 16:14 ..
    dr–x+   6 gneagle staff   204 Apr 30 12:06 .gneagle
    –rw–rr    1 root    wheel     0 Sep 23  2007 .localized
    drwxrwxrwt   24 root    wheel   816 Apr 30 14:46 Shared
    drwxrr  115 gneagle staff  3978 May  2 12:28 gneagle

    Note the new ".gneagle" directory. Further investigation will show the gneagle.sparsebundle file is now inside the .gneagle directory, and the disk image is mounted on /Users/gneagle:

    [mbp:/Users] root# mount
    /dev/disk0s3 on / (hfs, local, journaled)
    devfs on /dev (devfs, local)
    fdesc on /dev (fdesc, union)
    map –hosts on /net (autofs, automounted)
    map auto_home on /home (autofs, automounted)
    /dev/disk1s2 on /Users/gneagle (hfs, local, nodev, nosuid, journaled)

    So let's put this knowledge to use.

    On rare occasions on Tiger machines, you may encounter a situation where a FileVault–protected user cannot log in. You login to the machine with an admin account, and look in the /Users/username folder, and find the sparseimage file missing! Instead of panicking, you use your hard–earned systems administration knowledge, and you remember to look for a ".username" directory under /Users. You find it, and inside, the username.sparseimage file. You then move the sparseimage file back into the /Users/username directory, remove the /Users/.username directory, and tell the user to try to log in. They succeed, and you are a sysadmin hero.

    What has happened is that the machine crashed while the user was logged in, and the sparseimage file was not moved back into /Users/username, as it would be after a normal logout. When this happens, Tiger does not always fix things after the reboot, so you may need to help things along.

    Wrap–up

    Thus concludes our look at implementing FileVault in an enterprise environment. We've looked at preparation tasks and deployment options. We've identified some common issues and user experiences, and demonstrated some tools and strategies to deal with these. You now have the knowledge to confidently help protect your organization's private data and intellectual property with FileVault's home directory encryption.


    Greg Neagle is a member of the steering committee of the Mac OS X Enterprise Project (macenterprise.org) and is a senior systems engineer at a large animation studio. Greg has been working with the Mac since 1984, and with OS X since its release. He can be reached at gregneagle@mac.com.

  •  

    Community Search:
    MacTech Search:

    Software Updates via MacUpdate

    Logic Pro X 10.3 - Music creation and au...
    Logic Pro X is the most advanced version of Logic ever. Sophisticated new tools for professional songwriting, editing, and mixing are built around a modern interface that's designed to get creative... Read more
    iMazing 2.1.8 - Complete iOS device mana...
    iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
    Civilization VI 1.0.2 - Next iteration o...
    Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
    TurboTax 2016 - Manage your 2016 U.S. ta...
    TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more
    Microsoft Office 2016 15.30 - Popular pr...
    Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
    FotoMagico 5.3 - Powerful slideshow crea...
    FotoMagico lets you create professional slideshows from your photos and music with just a few, simple mouse clicks. It sports a very clean and intuitive yet powerful user interface. High image... Read more
    Acorn 5.6.1 - Bitmap image editor.
    Acorn is a new image editor built with one goal in mind - simplicity. Fast, easy, and fluid, Acorn provides the options you'll need without any overhead. Acorn feels right, and won't drain your bank... Read more
    Dash 3.4.3 - Instant search and offline...
    Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
    Microsoft Remote Desktop 8.0.37 - Connec...
    With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
    Macs Fan Control 1.4.7.0 - Monitor and c...
    Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more

    Turbo League Guide: How to tame the cont...
    | Read more »
    Fire Emblem: Heroes coming to Google Pla...
    Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
    ReSlice (Music)
    ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »
    Stickman Surfer rides in with the tide t...
    Stickson is back and this time he's taken up yet another extreme sport - surfing. Stickman Surfer is out this Thursday on both iOS and Android, so if you've been following the other Stickman adventures, you might be interested in picking this one... | Read more »
    Z-Exemplar (Games)
    Z-Exemplar 1.4 Device: iOS Universal Category: Games Price: $3.99, Version: 1.4 (iTunes) Description: | Read more »
    5 dastardly difficult roguelikes like th...
    Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »
    Last week on PocketGamer
    Welcome to a weekly feature looking back on the past seven days of coverage on our sister website, PocketGamer. It’s taken a while for 2017 to really get going, at least when it comes to the world of portable gaming. Thank goodness, then, for... | Read more »
    ROME: Total War - Barbarian Invasion set...
    To the delight of mobile strategy fans, Feral Interactive released ROME: Total War just a few months ago. Now the game's expansion, Barbarian Invasion is marching onto iPads as a standalone release. [Read more] | Read more »
    Yuri (Games)
    Yuri 1.0 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: It's night. Yuri opens his eyes. He wakes up in a strange forest.The small, courageous explorer rides on his bed on casters in this... | Read more »
    Space schmup Xenoraid launches on the Ap...
    10Tons Xenoraid is out today on the App Store, bringing some high-speed space action to your mobile gadgets just in time for the weekend. The company's last premium title, another sci-fi game titled Neon Chrome, did quite well for itself, so... | Read more »

    Price Scanner via MacPrices.net

    Laptop Market – Flight To Quality? – The ‘Boo...
    Preliminary quarterly PC shipments data released by Gartner Inc. last week reveal an interesting disparity between sales performance of major name PC vendors as opposed to that of less well-known... Read more
    IBM and Bell Transform Canadian Enterprise Mo...
    IBM and Bell Canada have announced they are joining forces to offer IBM MobileFirst for iOS market-ready enterprise applications for iPad, iPhone or Apple Watch. Bell, Canada’s largest communications... Read more
    Otter Products is Closing… For a Day of Givin...
    On Thursday, Feb. 9, Otter Products is closing doors to open hearts. In partnership with the OtterCares Foundation, the company is pausing operations for a day so all employees can volunteer with... Read more
    15-inch 2.2GHz Retina MacBook Pro on sale for...
    Amazon has 2015 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) available for $1799.99 including free shipping. Apple charges $1999 for this model, so Amazon’s price is represents a $200 savings. Read more
    Back in stock: Apple refurbished 13-inch Reti...
    Apple has Certified Refurbished 2015 13″ Retina MacBook Pros available for up to $360 off original MSRP, starting at $1099. An Apple one-year warranty is included with each model, and shipping is... Read more
    CalcTape for macOS 1.2 Adding Machine App for...
    schoettler Software has announced CalcTape 1.2, an update to their desktop calculator for macOS. When it comes to adding long columns of numbers, doing complex calculations or playing around with... Read more
    New MacBooks And MacBook Pros WIth Kaby Lake...
    Digitimes’ Joseph Tsai cites a Chinese-language Economic Daily News (EDN) report that unnamed market watchers are predicting Apple MacBook shipments to grow 10 percent in 2017, and projecting 15... Read more
    New 2016 13-inch MacBook Pros on sale for up...
    B&H Photo has the new 2016 13″ MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.9GHz/512GB Touch Bar MacBook Pro... Read more
    New 15-inch Touch Bar MacBook Pros in stock a...
    B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
    Opera Announces Neon Concept Browser For Mac
    Opera is inviting users to get a glimpse of what Opera for computers could become with its Opera Neon browser concept. Each Opera Neon feature is described as “an alternate reality” for the Opera... Read more

    Jobs Board

    *Apple* Retail - Multiple Positions - Apple,...
    SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
    *Apple* Retail - Multiple Positions (Multi-L...
    Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
    *Apple* Retail - Multiple Positions - Apple,...
    Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
    *Apple* & PC Desktop Support Technician...
    Apple & PC Desktop Support Technician job in Stamford, CT We have immediate job openings for several Desktop Support Technicians with one of our most well-known Read more
    *Apple* macOS Systems Integration Administra...
    …most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing Read more
    All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.