Changes in iOS 7 Security Make Kernel More Vulnerable to Attack

by

A security researcher claims changes Apple made to tighten its kernel security system in iOS 7 instead weakened the system, making it less secure than its iOS 6 counterpart. (Via CNET and ThreatPost) Azimuth Security researcher Tarjei Mandt discovered the flaw and presented his findings last week at CanSecWest.

The security flaw involves the random number generator Apple uses to secure its kernel. In iOS 6, the number generator that encrypted the kernel derived its values in part from the CPU clock counter. Because it was based on time, the encryption was only marginally secure as the output values were predictable, especially when examining successive numbers.

ios7-early-random-number
Apple was aware of the limitations in iOS 6 and attempted to tighten security in iOS 7 by changing the random number generator to a linear congruential generator, which is more susceptible to brute force attacks.

The problem with the new generator in iOS 7 is that it uses a linear recursion algorithm, Mandt said, which has "more correlation" between the values it generates. That makes them easier to extrapolate and guess, he said.

This flaw potentially allows a malicious hacker to gain kernel-level access to an iOS device via an unpatched vulnerability. The kernel is the base part of the iOS operating system and controls low-level functions such as security and resource allocation.

Apple approached Mandt about his findings and asked for his CanSecWest slide presentation.

Top Rated Comments

Calexander3103 Avatar
89 months ago

Deliberate back door?


Couldn't have been an accident that someone missed, could it? Nah....everyone get your tin foil hats out cause everyone's out to get us.


In reality, props to white-hat hackers like Mandt
Score: 9 Votes (Like | Disagree)
C DM Avatar
89 months ago

I like how negative things like this never makes it to the Front Page and not many throwing a punch at Apple like they do for other companies. I am sure if it was any other company, this news would have been the first frontage news. I feel this is done deliberately by MacRumors for generating $$. Just pathetic.

I came across this story on the front page of MacRumors, as I'm sure many others did.
Score: 3 Votes (Like | Disagree)
Laird Knox Avatar
89 months ago
Random Number Generators are a tricky business. The company I work for has a whole slew of patents and protected IP just for the RNG we use.
Score: 3 Votes (Like | Disagree)
ArtOfWarfare Avatar
89 months ago
Modern Intel chips (made after 2008 I think) have ISK which produces actual random values rather than pseudo ones. I guess ARM lacks that right now.
Score: 3 Votes (Like | Disagree)
dumastudetto Avatar
89 months ago

Deliberate back door?


No. Apple would never do this. They never compromise on customer security for anyone.
Score: 3 Votes (Like | Disagree)
gnasher729 Avatar
89 months ago

It's not in the slides but I'd be curious to know how much brute force is required?
It reads like a restart would require calculation to start again?

Could an app be crafted inside the sandbox to not only gather enough info but to also then have enough time to process that info to get the information it needs to launch an attack without highlighting is presents.

Yes "security by obscurity" = bad. Yes, could be better.
Still if attack needs more than minutes of full throttle processing it goes to take some fairly careful crafting to hid it. Putting more in "Alert but not Alarmed" territory.


It's very hard to say how much of a problem there actually is. My understanding - which may be wrong - is that this random number generator is used at the very early stages while iOS is booting, and is then replaced with something a lot stronger. There's the claim that the random number sequence could be predicted, but then I wonder which non-Apple software would be running on the device at the early stages when this random number generator is in use. Quite possibly none at all.
Score: 2 Votes (Like | Disagree)

Top Stories

iphone 5s black slate

Images of Unreleased iPhone 5s in Black and Slate Shared Online

Sunday January 17, 2021 9:47 am PST by
Twitter user @DongleBookPro has today shared images of a prototype iPhone 5s in an unreleased Black and Slate color. The iPhone 5s was launched in September 2013. The device featured Touch ID, a 64-bit processor, and a True Tone LED flash for the first time. Other new features included a five-element lens with an f/2.2 aperture, a 15 percent larger camera sensor, Burst Mode, and Slo-Mo...
iP12 charge airpods feature 2

Hidden iPhone 12 Hardware Feature Could Still be Unlocked

Thursday January 14, 2021 2:51 am PST by
All iPhone 12 and iPhone 12 Pro models purportedly have a hidden reverse wireless charging feature, according to an FCC filing. The feature has not yet been activated, but could yet be unlocked for an upcoming Apple accessory. The FCC filing suggests that iPhone 12 models contain the hardware for Wireless Power Transfer (WPT) to accessories: In addition to being able to be charged by a...
Top Stories 43 Feature

Top Stories: MacBook Pro, iMac, Mac Pro, and iPhone Rumors, Best of CES 2021

Saturday January 16, 2021 6:00 am PST by
This week was sure a busy one in the Apple world, with a flurry of announcements out of CES early in the week followed by a rash of Mac- and iPhone-related rumors later in the week. The new rumors this week included details on updated MacBook Pro, iMac, and Mac Pro models, as well as a few other tidbits, so make sure to read on below to get caught up! Kuo: New MacBook Pro Models to...
macbook pro flexgate

Apple Extends 13-Inch MacBook Pro Backlight Repair Program

Sunday January 17, 2021 10:31 am PST by
Apple this week extended its worldwide 13-inch MacBook Pro Display Backlight Service Program, authorizing coverage for eligible notebooks for up to five years after the original purchase date or up to three years after the start date of the program, whichever is longer. The previous cutoff was four years after the original purchase date. Apple launched the program on May 21, 2019 after...
foldable iPhone concept feature

Apple Testing In-Display Fingerprint Sensor for iPhone 13, Foldable iPhone Also in the Works

Friday January 15, 2021 1:46 pm PST by
Apple has started "early work" on an iPhone that has a foldable display, according to a new report from Bloomberg's Mark Gurman. Though testing of a foldable iPhone has begun, Apple has not committed to releasing a device that has a foldable display. Development has not yet expanded beyond a display and Apple does not have full foldable iPhone prototypes in its labs. Like foldable...
google maps detailed street level e1611052089473

Google Maps Gains Enhanced Street-Level Detail in Four Major Cities

Tuesday January 19, 2021 2:34 am PST by
Google Maps has quietly been updated to include significantly more detailed street-level information in a handful of key cities around the world. Upon zooming in, Google's maps for Central London, Tokyo, San Francisco, and New York now benefit from shapes and widths that match the scale of roads more accurately. Meanwhile, enhanced graphical representations of sidewalks, crosswalks,...
16inchmacbookpromain

Kuo: New MacBook Pro Models to Feature Flat-Edged Design, MagSafe, No Touch Bar and More Ports

Thursday January 14, 2021 9:32 pm PST by
Apple is working on two new MacBook Pro models that will feature significant design changes, well-respected Apple analyst Ming-Chi Kuo said today in a note to investors that was obtained by MacRumors. According to Kuo, Apple is developing two models in 14 and 16-inch size options. The new MacBook Pro machines will feature a flat-edged design, which Kuo describes as "similar to the iPhone 12" ...
macbook pro screensaver table

Some M1 Macs Affected By Fast User Switching Screensaver Bug

Monday January 18, 2021 1:57 am PST by
A growing number of user reports online suggest some of Apple's M1 Mac models are susceptible to a Fast User Switching bug that spontaneously activates the screensaver and leaves the user unable to dismiss it. In macOS Big Sur, Fast User Switching allows users to quickly switch between user accounts without having to completely log out. Based on posts in the MacRumors forums, Apple...
iphone x camera close

iOS 14.4 Will Introduce Warning on iPhones With Non-Genuine Cameras

Thursday January 14, 2021 8:07 am PST by
In the second beta of iOS 14.4 seeded to developers and public testers this week, MacRumors contributor Steve Moser has discovered code indicating that Apple will be introducing a new warning on iPhones that have had their camera repaired or replaced with aftermarket components rather than genuine Apple components. "Unable to verify this iPhone has a genuine Apple camera," the message will...
apple fitness plus burn bar

Fitness+ Subscribers Now Have Nearly 300 Workouts to Choose From

Monday January 18, 2021 3:24 am PST by
Apple on Monday added over two dozen new video workout sessions to Fitness+, continuing a recent trend of building out the catalog of its fledgling subscription service on a weekly basis. Fitness+ launched December 14, 2020, and is designed to help Apple Watch owners keep fit through a series of guided workouts that are available across multiple workout categories. As you follow along with...