Frequently Asked Questions About Find My iPhone (and iPad)
I’ve been getting a lot of hits for my article on Protecting and Recovering Your iPhone and iPad from Loss and Theft, and the search queries I’m seeing in my logs, together with the visitor comments, have raised a number of recurring questions. I’ve decided to publish this one-stop-shop of answers for all of the different queries that I see people searching for when they arrive. Although my article addresses a number of these, I wanted to put them all in one post for easy reference. I’ll update this post as new questions crop up. Here goes, in no particular order:
New! iPhone Lockscreen Generator
When people ask me about the different ways they can protect their iPhone in case it gets lost or stolen, I usually point them in the direction of my article on Protecting and Recovering Your iPhone and iPad from Loss and Theft. I just updated that article to include a tip about creating a custom lockscreen image for your iPhone that may help someone return it to you in the event it gets lost.
A tip is all good and well, but creating such a customised image may be beyond the technical abilities of your average iPhone user, so I hacked together the brand new iPhone Lockscreen Generator!
http://lockscreengenerator.com
This free online tool allows anyone to create a customised lockscreen (currently with one of four background images), in less than a minute. Just enter your contact details (first name, alternate contact number), and maybe a short note for whomever finds your iPhone (reward maybe?), click generate, then tap/click on the image to download it. You can do this on your computer, and email yourself the image, or do it directly on your iPhone.
Once downloaded to your iPhone, you can set the image as your lockscreen wallpaper by going into the Photos app, tapping your image, then tap the ‘send to’ icon in the bottom left-hand corner of the screen, select Use as wallpaper > Set > Set Lock Screen.
Don’t forget to share this with your friends! You can even use one of the share links below ;) If you have any feedback or tips, let me know.
Charlie Miller Discovers iOS Code-Signing Bypass Vulnerability
Security researcher Charlie Miller (@0xcharlie) has discovered a significant flaw in iOS which may allow a malicious app on the App Store to download and execute arbitrary unsigned code. What this means for iPhone, iPad and iPod Touch users is that installing a malicious app may allow an attacker to obtain shell access to your device, and download contacts or images.
Apple reviews every app submitted to the App Store, which has meant that iOS users have not had to worry about outright malware. Since this vulnerability allows the apps to fetch code remotely, they can perform actions not reviewed by the App Store staff. Charlie had submitted a proof-of-concept app that was approved (see video below), but has since been removed by Apple.
The reason this vulnerability works is based around some changes Apple made in iOS 4.3 last year, which allowed Mobile Safari to run javascript at a more privileged level on the devices. This change required Apple to make an exception for Safari to execute unsigned code in a particular area of memory. Charlie Miller’s bug is allegedly a very unique case that allows any app to take advantage of this, and hence run their own unsigned code.
Charlie will be presenting the vulnerability in detail at the SysCan conference in Taiwan next week. Apple has already released a developer beta of iOS 5.0.1 which patches the recent iPad Smart Cover lock screen bypass, but I would not be at all surprised if they release another beta which includes a fix for this bug. Until then, be careful to only install apps from developers you trust.
[Update] Apple has kicked Charlie out of the Developer program. At first I felt that this was an extremely bad reaction on Apple’s part. That said, Apple is probably most upset that Charlie’s proof-of-concept app could have been installed by legitimate users. Regardless of Charlie’s intentions, this could constitute malware, and he should have removed the app as soon as he saw the flaw existed. The posting of his video above probably didn’t help matters either.
iPad Lock Screen Bypass Vulnerability using Smart Cover [Patched]
Marc Gurman at 9to5Mac has discovered a vulnerability on the iPad that allows for a limited bypass of the device’s lockscreen. Anyone with an iPad Smart Cover (or fridge magnet) can gain access to the previously-open app (or the home screen if no app was open).
By holding the power button to bring up the ‘Power Off’ screen, closing the smart cover, re-opening it (or just sliding a fridge magnet along the right-hand side of the device), and clicking cancel, the attacker will be dropped into the screen that was open before the iPad was locked. If the attacker gets dropped into the home screen, then they’ll be able to see the installed apps, but won’t be able to open anything. If Safari or Mail (or any other app) was the open when the device was locked, then the attacker would have access to that app.
Unlike Siri being available from the lock screen, which is not a security flaw (an unintended behaviour), this one actually is; and although an attacker does not get full control of the iPad, the severity depends on whether a sensitive app was being used before the device was locked.
Luckily it is possible to protect yourself against this bug in the interim by disabling Smart Covers in Settings > General > iPad Cover Lock/Unlock > Off. Expect Apple to patch this in iOS 5.0.1. Check out 9to5′s video below for a demonstration:
[Update] Apple did indeed patch this bug in iOS 5.0.1. Those of you who disabled your Smart Covers for security purposes can now re-enable them!
Securing Siri on a Locked iPhone 4S
Although I haven’t had the chance to play with her myself (does that sound wrong?), Siri seems like an awesome addition to the iPhone. It’s worth pointing out, however, that it is still possible to use Siri when the iPhone is locked – presumably for convenient ease-of-use. Unfortunately this means that anyone with physical access to your phone can access information including contacts, calendar items, SMS/iMessages, and also make calls and send emails or messages from you.
[Update] There have been a whole bunch of people crying about how this is a major security flaw. Just to dispel some of the myth… this is not a security flaw, it’s a design decision that Apple made based on usability. Yes, it’s a default setting that may introduce some vulnerabilities, but then again there are still lots of people who run around without passcodes. To be honest I’m usually the first to secure the hell out of everything, but in this case I feel they made the right decision for two reasons. First, Siri is obviously less useful as a hands-free assistant if you need to unlock your phone every time; and secondly making it easier to use will help drive the adoption of Siri.
Luckily Apple thought of this on at least two levels. First, if you ask Siri to unlock your iPhone she’ll respectfully tell you that she “can’t unlock your phone for you”. Secondly – and this is the important one – it is possible to disable the use of Siri when the iPhone is locked. The option now lives in Settings > General > Passcode Lock, where you can set Siri to Off.
Needless to say (contrary to the screenshot), I recommend setting ‘Require Passcode’ to Immediately, turn Simple Passcode off so you can set a 5-or-more-digit PIN, set ‘Siri’ to off to prevent access when your iPhone is locked, and turn on Erase Data after 10 failed passcode attempts.
Siri is great, but let’s not make it easy for someone to social-engineer her into betraying you. See my other post for more details on protecting your iPhone from loss and theft.
In other news… you can tell Siri to use a specific nickname when talking to you. It’s important to note, however, that the nickname will be put into your VCard. So be careful if you tell her to call you her pimp, and then send someone your contact details ;)
Apple Releases Slew of Security Updates (OSX, Safari, iTunes, iOS 5, aTV)
I wasn’t going to post about last week’s fairly significant iTunes update, but then Apple went and patched a whole bunch of vulnerabilities across the board. Some of these are fairly significant so I thought I would provide a short breakdown of the changes. Either way, you should definitely be patching all of your Apple devices and software tonight.
Hit the jump for a summary of the key vulnerabilities patched in Apple’s security updates.
New iCloud Webmail, Contacts, Calendar and Find My iPhone
Before making the switch from MobileMe to iCloud last week, I was looking around for posts about iCloud’s new webmail and didn’t find any. As I’d just installed the iOS 5 GM on my iPhone, I was eager to get iCloud going as well to get a head start, but wanted to investigate the iCloud services first. I didn’t find any useful posts, but made the switch anyway. Seeing as iCloud will be free to all users now, I thought I’d give you a heads up into what you can expect!
Farewell Steve (1955-2011)
Steve Jobs died today at the age of 56. As someone who grew up with a Mac Classic and followed Steve and Apple through the ups and downs, he’s always been a personal inspiration. Steve was a visionary and has shaped the world in ways that will reverberate into the future for decades to come. It fills me with a profound sadness to know that someone so unique is gone in the prime of his life. I had the pleasure of watching Steve give a keynote at the Mac Expo in Paris in what seems like many years ago now – I regret never having had the opportunity to shake his hand, and thank him for all that he’s given us.
Thank you Steve. You will be remembered, always.
[Update] Apple has posted the video of their Celebrating Steve event from October 19th.
Extracting and Cracking Mac OS X Lion Password Hashes [Updated]
The Defence in Depth blog has a post about a flaw in Lion’s redesigned authentication mechanisms and Directory Services. In short, it is possible to change the password of the currently logged in user by simply running the following command in the terminal, and it won’t ask you for the user’s current password:
$ dscl localhost -passwd /Search/Users/<username>
In Lion it is also easy to dump a user’s SHA-512 password hash using the following command:
$ dscl localhost -read /Search/Users/<username>
Then look for the dsAttrTypeNative:ShadowHashData chunk in the output (sample below). The hex string in red is the salt, and the green is the hash.
62706c69 73743030 d101025d 53414c54 45442d53 48413531 324f1044 74911f72 3bd2f66a 3255e0af 4b85c639 776d510b 63f0b939 c432ab6e 082286c4 7586f19b 4e2f3aab 74229ae1 24ccb11e 916a7a1c 9b29c64b d6b0fd6c bd22e7b1 f0ba1673 080b1900 00000000 00010100 00000000 00000300 00000000 00000000 00000000 000060
Cracking password hashes can be done using his custom Python script, or John the Ripper (with the Jumbo patch). Note that even if someone manages to obtain your password hash, if you’re using a strong password it will be extremely difficult for them to recover it. Seems like both of these are important but fairly low-risk flaws introduced into Lion. Hopefully Apple will look into these for the next update.
[Update 1] While waiting for an Apple-supplied security update, it is possible to protect yourself from this vulnerability by adjusting the permissions on dscl:
sudo chmod go-x /usr/bin/dscl
This makes it so that only root can execute dscl. To revert this simply run:
sudo chmod go+x /usr/bin/dscl
[Update 2] This vulnerability was patched in Mac OS X 10.7.2.
Security Update 2011-005 Fixes DigiNotar SSL Vulnerability
Apple has finally issued Security Update 2011-005 to address the recent issues around compromised Dutch certificate authority DigiNotar. It was discovered that at least 531 fraudulent SSL certificates were issued by DigiNotar, leading to their root certificate being revoked in all major operating systems and browsers over the past two weeks. A man-in-the-middle attacker in possession of one of these certs (eg. Google, Skype), would be able to intercept SSL-encrypted traffic to those sites. It is believed that the use of these fraudulent certs may have been limited to the Iranian government.
This patch removes the DigiNotar CA from the trusted root certificates in the Mac OS X keychain (which is also used by Safari) for Lion and Snow Leopard. Unfortunately no patch has been issued for Leopard (10.5) users, leaving them at a heightened risk from these bad certificates. It is recommended that Leopard users delete the DigiNotar CA certificate from the Keychain using the following steps:
- Open Keychain Access (/Applications/Utilities/Keychain Access)
- Click on the System Roots keychain in the top-left hand panel
- Click on Certificates in the bottom-left hand panel
- Type DigiNotar into the search field in the top right.
- Right-click on the DigiNotar Root CA, and select Delete.
# sudo /usr/bin/security delete-certificate -Z C060ED44CBD881BD0EF86C0BA287DDCF8167478C /System/Library/Keychains/SystemRootCertificates.keychain
Firefox users should update to the latest version of Firefox. Here is the full Apple description for this update:
Security Update 2011-005
- Certificate Trust Policy Available for: Mac OS X v10.6.8, Mac OS X Server v10.6.8, OS X Lion v10.7.1, Lion Server v10.7.1Impact: An attacker with a privileged network position may intercept user credentials or other sensitive information
Description: Fraudulent certificates were issued by multiple certificate authorities operated by DigiNotar. This issue is addressed by removing DigiNotar from the list of trusted root certificates, from the list of Extended Validation (EV) certificate authorities, and by configuring default system trust settings so that DigiNotar’s certificates, including those issued by other authorities, are not trusted.
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