Entries Tagged "iOS"

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Recovering an iPhone 5c Passcode

Remember the San Bernardino killer’s iPhone, and how the FBI maintained that they couldn’t get the encryption key without Apple providing them with a universal backdoor? Many of us computer-security experts said that they were wrong, and there were several possible techniques they could use. One of them was manually removing the flash chip from the phone, extracting the memory, and then running a brute-force attack without worrying about the phone deleting the key.

The FBI said it was impossible. We all said they were wrong. Now, Sergei Skorobogatov has proved them wrong. Here’s his paper:

Abstract: This paper is a short summary of a real world mirroring attack on the Apple iPhone 5c passcode retry counter under iOS 9. This was achieved by desoldering the NAND Flash chip of a sample phone in order to physically access its connection to the SoC and partially reverse engineering its proprietary bus protocol. The process does not require any expensive and sophisticated equipment. All needed parts are low cost and were obtained from local electronics distributors. By using the described and successful hardware mirroring process it was possible to bypass the limit on passcode retry attempts. This is the first public demonstration of the working prototype and the real hardware mirroring process for iPhone 5c. Although the process can be improved, it is still a successful proof-of-concept project. Knowledge of the possibility of mirroring will definitely help in designing systems with better protection. Also some reliability issues related to the NAND memory allocation in iPhone 5c are revealed. Some future research directions are outlined in this paper and several possible countermeasures are suggested. We show that claims that iPhone 5c NAND mirroring was infeasible were ill-advised.

Susan Landau explains why this is important:

The moral of the story? It’s not, as the FBI has been requesting, a bill to make it easier to access encrypted communications, as in the proposed revised Burr-Feinstein bill. Such “solutions” would make us less secure, not more so. Instead we need to increase law enforcement’s capabilities to handle encrypted communications and devices. This will also take more funding as well as redirection of efforts. Increased security of our devices and simultaneous increased capabilities of law enforcement are the only sensible approach to a world where securing the bits, whether of health data, financial information, or private emails, has become of paramount importance.

Or: The FBI needs computer-security expertise, not backdoors.

Patrick Ball writes about the dangers of backdoors.

EDITED TO ADD (9/23): Good article from the Economist.

Posted on September 15, 2016 at 8:54 AMView Comments

iPhone Zero-Day Used by UAE Government

Last week, Apple issued a critical security patch for the iPhone: iOS 9.3.5. The incredible story is that this patch is the result of investigative work by Citizen Lab, which uncovered a zero-day exploit being used by the UAE government against a human rights defender. The UAE spyware was provided by the Israeli cyberweapons arms manufacturer NSO Group.

This is a big deal. iOS vulnerabilities are expensive, and can sell for over $1M. That we can find one used in the wild and patch it, rendering it valueless, is a major win and puts a huge dent in the vulnerabilities market. The more we can do this, the less valuable these zero-days will be to both criminals and governments—and to criminal governments.

Citizen Lab blog post and report. New York Times article. More news articles.

Posted on August 29, 2016 at 1:21 PMView Comments

iMessage Encryption Flaw Found and Fixed

Matthew Green and team found and reported a significant iMessage encryption flaw last year.

Green suspected there might be a flaw in iMessage last year after he read an Apple security guide describing the encryption process and it struck him as weak. He said he alerted the firm’s engineers to his concern. When a few months passed and the flaw remained, he and his graduate students decided to mount an attack to show that they could pierce the encryption on photos or videos sent through iMessage.

It took a few months, but they succeeded, targeting phones that were not using the latest operating system on iMessage, which launched in 2011.

To intercept a file, the researchers wrote software to mimic an Apple server. The encrypted transmission they targeted contained a link to the photo stored in Apple’s iCloud server as well as a 64-digit key to decrypt the photo.

Although the students could not see the key’s digits, they guessed at them by a repetitive process of changing a digit or a letter in the key and sending it back to the target phone. Each time they guessed a digit correctly, the phone accepted it. They probed the phone in this way thousands of times.

“And we kept doing that,” Green said, “until we had the key.”

A modified version of the attack would also work on later operating systems, Green said, adding that it would likely have taken the hacking skills of a nation-state.

This flaw is fixed in iOS 9.3. (You should download and install it now.)

I wrote about this flaw in IEEE Security and Privacy earlier this year:

Going back to the new vulnerability that you’ll learn about in mid-February, the lead researcher wrote to me: “If anyone tells you that [the vendor] can just ‘tweak’ the system a little bit to add key escrow or to man-in-the-middle specific users, they need to spend a few days watching the authentication dance between [the client device/software] and the umpteen servers it talks to just to log into the network. I’m frankly amazed that any of it works at all, and you couldn’t pay me enough to tamper with any of it.” This is an important piece of wisdom.

The designers of this system aren’t novices. They’re an experienced team with some of the best security engineers in the field. If these guys can’t get the security right, just imagine how much worse it is for smaller companies without this team’s level of expertise and resources. Now imagine how much worse it would be if you add a government-mandated back door. There are more opportunities to get security wrong, and more engineering teams without the time and expertise necessary to get

Related: A different iOS flaw was reported last week. Called AceDeceiver, it is a Trojan that allows an attacker to install malicious software onto an iOS device, bypassing Apple’s DRM protections. I don’t believe that Apple has fixed this yet, although it seems as if Apple just has to add a certificate revocation list, or make the certs nonreplayable by having some mandatory interaction with the iTunes store.

EDITED (4/14): The paper describing the iMessage flaw.

Posted on March 21, 2016 at 1:45 PMView Comments

Mac OS X, iOS, and Flash Had the Most Discovered Vulnerabilities in 2015

Interesting analysis:

Which software had the most publicly disclosed vulnerabilities this year? The winner is none other than Apple’s Mac OS X, with 384 vulnerabilities. The runner-up? Apple’s iOS, with 375 vulnerabilities.

Rounding out the top five are Adobe’s Flash Player, with 314 vulnerabilities; Adobe’s AIR SDK, with 246 vulnerabilities; and Adobe AIR itself, also with 246 vulnerabilities. For comparison, last year the top five (in order) were: Microsoft’s Internet Explorer, Apple’s Mac OS X, the Linux Kernel, Google’s Chrome, and Apple’s iOS.

The article goes on to explain why Windows vulnerabilities might be counted higher, and gives the top 50 software packages for vulnerabilities.

The interesting discussion topic is how this relates to how secure the software is. Is software with more discovered vulnerabilities better because they’re all fixed? Is software with more discovered vulnerabilities less secure because there are so many? Or are they all equally bad, and people just look at some software more than others? No one knows.

Posted on January 11, 2016 at 2:33 PMView Comments

Personal Data Sharing by Mobile Apps

Interesting research:

“Who Knows What About Me? A Survey of Behind the Scenes Personal Data Sharing to Third Parties by Mobile Apps,” by Jinyan Zang, Krysta Dummit, James Graves, Paul Lisker, and Latanya Sweeney.

We tested 110 popular, free Android and iOS apps to look for apps that shared personal, behavioral, and location data with third parties.

73% of Android apps shared personal information such as email address with third parties, and 47% of iOS apps shared geo-coordinates and other location data with third parties.

93% of Android apps tested connected to a mysterious domain, safemovedm.com, likely due to a background process of the Android phone.

We show that a significant proportion of apps share data from user inputs such as personal information or search terms with third parties without Android or iOS requiring a notification to the user.

EDITED TO ADD: News article.

Posted on November 13, 2015 at 6:08 AMView Comments

$1M Bounty for iPhone Hack

I don’t know whether to believe this story. Supposedly the startup Zerodium paid someone $1M for an iOS 9.1 and 9.2b hack.

Bekrar and Zerodium, as well as its predecessor VUPEN, have a different business model. They offer higher rewards than what tech companies usually pay out, and keep the vulnerabilities secret, revealing them only to certain government customers, such as the NSA.

I know startups like publicity, but certainly an exploit like this is more valuable if it’s not talked about.

So this might be real, or it might be a PR stunt. But companies selling exploits to governments is certainly real.

Another news article.

Posted on November 3, 2015 at 2:31 PMView Comments

How the CIA Might Target Apple's XCode

The Intercept recently posted a story on the CIA’s attempts to hack the iOS operating system. Most interesting was the speculation that it hacked XCode, which would mean that any apps developed using that tool would be compromised.

The security researchers also claimed they had created a modified version of Apple’s proprietary software development tool, Xcode, which could sneak surveillance backdoors into any apps or programs created using the tool. Xcode, which is distributed by Apple to hundreds of thousands of developers, is used to create apps that are sold through Apple’s App Store.

The modified version of Xcode, the researchers claimed, could enable spies to steal passwords and grab messages on infected devices. Researchers also claimed the modified Xcode could “force all iOS applications to send embedded data to a listening post.” It remains unclear how intelligence agencies would get developers to use the poisoned version of Xcode.

Researchers also claimed they had successfully modified the OS X updater, a program used to deliver updates to laptop and desktop computers, to install a “keylogger.”

It’s a classic application of Ken Thompson’s classic 1984 paper, “Reflections on Trusting Trust,” and a very nasty attack. Dan Wallach speculates on how this might work.

Posted on March 16, 2015 at 7:38 AMView Comments

Apple Copies Your Files Without Your Knowledge or Consent

The latest version of Apple’s OS automatically syncs your files to iCloud Drive, even files you choose to store locally. Apple encrypts your data, both in transit and in iCloud, with a key it knows. Apple, of course, complies with all government requests: FBI warrants, subpoenas, and National Security Letters—as well as NSA PRISM and whatever-else-they-have demands.

EDITED TO ADD (10/28): See comments. This seems to be way overstated. I will look at this again when I have time, probably tomorrow.

EDITED TO ADD (10/28): This is a more nuanced discussion of this issue. At this point, it seems clear that there is a lot less here than described in the blog post below.

EDITED TO ADD (10/29): There is something here. It only affects unsaved documents, and not all applications. But the OS’s main text editor is one of them. Yes, this feature has been in the OS for a while, but that’s not a defense. It’s both dangerous and poorly documented.

Posted on October 28, 2014 at 6:21 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.