Entries Tagged "iOS"

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Apple’s NeuralHash Algorithm Has Been Reverse-Engineered

Apple’s NeuralHash algorithm—the one it’s using for client-side scanning on the iPhone—has been reverse-engineered.

Turns out it was already in iOS 14.3, and someone noticed:

Early tests show that it can tolerate image resizing and compression, but not cropping or rotations.

We also have the first collision: two images that hash to the same value.

The next step is to generate innocuous images that NeuralHash classifies as prohibited content.

This was a bad idea from the start, and Apple never seemed to consider the adversarial context of the system as a whole, and not just the cryptography.

Posted on August 18, 2021 at 11:51 AM • View Comments

iPhone Apps Stealing Clipboard Data

iOS apps are repeatedly reading clipboard data, which can include all sorts of sensitive information.

While Haj Bakry and Mysk published their research in March, the invasive apps made headlines again this week with the developer beta release of iOS 14. A novel feature Apple added provides a banner warning every time an app reads clipboard contents. As large numbers of people began testing the beta release, they quickly came to appreciate just how many apps engage in the practice and just how often they do it.

This YouTube video, which has racked up more than 87,000 views since it was posted on Tuesday, shows a small sample of the apps triggering the new warning.

EDITED TO ADD (7/6): LinkedIn and Reddit are doing this.

Posted on June 29, 2020 at 10:24 AM • View Comments

iOS XML Bug

This is a good explanation of an iOS bug that allowed someone to break out of the application sandbox. A summary:

What a crazy bug, and Siguza’s explanation is very cogent. Basically, it comes down to this:

  • XML is terrible.
  • iOS uses XML for Plists, and Plists are used everywhere in iOS (and MacOS).
  • iOS’s sandboxing system depends upon three different XML parsers, which interpret slightly invalid XML input in slightly different ways.

So Siguza’s exploit ­—which granted an app full access to the entire file system, and more ­- uses malformed XML comments constructed in a way that one of iOS’s XML parsers sees its declaration of entitlements one way, and another XML parser sees it another way. The XML parser used to check whether an application should be allowed to launch doesn’t see the fishy entitlements because it thinks they’re inside a comment. The XML parser used to determine whether an already running application has permission to do things that require entitlements sees the fishy entitlements and grants permission.

This is fixed in the new iOS release, 13.5 beta 3.

Comment:

Implementing 4 different parsers is just asking for trouble, and the “fix” is of the crappiest sort, bolting on more crap to check they’re doing the right thing in this single case. None of this is encouraging.

More commentary. Hacker News thread.

Posted on May 7, 2020 at 9:56 AM • View Comments

New Unpatchable iPhone Exploit Allows Jailbreaking

A new iOS exploit allows jailbreaking of pretty much all version of the iPhone. This is a huge deal for Apple, but at least it doesn’t allow someone to remotely hack people’s phones.

Some details:

I wanted to learn how Checkm8 will shape the iPhone experience­—particularly as it relates to security­—so I spoke at length with axi0mX on Friday. Thomas Reed, director of Mac offerings at security firm Malwarebytes, joined me. The takeaways from the long-ranging interview are:

  • Checkm8 requires physical access to the phone. It can’t be remotely executed, even if combined with other exploits.
  • The exploit allows only tethered jailbreaks, meaning it lacks persistence. The exploit must be run each time an iDevice boots.
  • Checkm8 doesn’t bypass the protections offered by the Secure Enclave and Touch ID.
  • All of the above means people will be able to use Checkm8 to install malware only under very limited circumstances. The above also means that Checkm8 is unlikely to make it easier for people who find, steal or confiscate a vulnerable iPhone, but don’t have the unlock PIN, to access the data stored on it.
  • Checkm8 is going to benefit researchers, hobbyists, and hackers by providing a way not seen in almost a decade to access the lowest levels of iDevices.

Also:

“The main people who are likely to benefit from this are security researchers, who are using their own phone in controlled conditions. This process allows them to gain more control over the phone and so improves visibility into research on iOS or other apps on the phone,” Wood says. “For normal users, this is unlikely to have any effect, there are too many extra hurdles currently in place that they would have to get over to do anything significant.”

If a regular person with no prior knowledge of jailbreaking wanted to use this exploit to jailbreak their iPhone, they would find it extremely difficult, simply because Checkm8 just gives you access to the exploit, but not a jailbreak in itself. It’s also a ‘tethered exploit’, meaning that the jailbreak can only be triggered when connected to a computer via USB and will become untethered once the device restarts.

Posted on October 8, 2019 at 5:24 AM • View Comments

iOS 12.1 Vulnerability

This is really just to point out that computer security is really hard:

Almost as soon as Apple released iOS 12.1 on Tuesday, a Spanish security researcher discovered a bug that exploits group Facetime calls to give anyone access to an iPhone users’ contact information with no need for a passcode.

[…]

A bad actor would need physical access to the phone that they are targeting and has a few options for viewing the victim’s contact information. They would need to either call the phone from another iPhone or have the phone call itself. Once the call connects they would need to:

  • Select the Facetime icon
  • Select “Add Person”
  • Select the plus icon
  • Scroll through the contacts and use 3D touch on a name to view all contact information that’s stored.

Making the phone call itself without entering a passcode can be accomplished by either telling Siri the phone number or, if they don’t know the number, they can say “call my phone.” We tested this with both the owners’ voice and a strangers voice, in both cases, Siri initiated the call.

Posted on November 8, 2018 at 6:35 AM • View Comments

Bypassing Passcodes in iOS

Last week, a story was going around explaining how to brute-force an iOS password. Basically, the trick was to plug the phone into an external keyboard and trying every PIN at once:

We reported Friday on Hickey’s findings, which claimed to be able to send all combinations of a user’s possible passcode in one go, by enumerating each code from 0000 to 9999, and concatenating the results in one string with no spaces. He explained that because this doesn’t give the software any breaks, the keyboard input routine takes priority over the device’s data-erasing feature.

I didn’t write about it, because it seemed too good to be true. A few days later, Apple pushed back on the findings—and it seems that it doesn’t work.

This isn’t to say that no one can break into an iPhone. We know that companies like Cellebrite and Grayshift are renting/selling iPhone unlock tools to law enforcement—which means governments and criminals can do the same thing—and that Apple is releasing a new feature called “restricted mode” that may make those hacks obsolete.

Grayshift is claiming that its technology will still work.

Former Apple security engineer Braden Thomas, who now works for a company called Grayshift, warned customers who had bought his GrayKey iPhone unlocking tool that iOS 11.3 would make it a bit harder for cops to get evidence and data out of seized iPhones. A change in the beta didn’t break GrayKey, but would require cops to use GrayKey on phones within a week of them being last unlocked.

“Starting with iOS 11.3, iOS saves the last time a device has been unlocked (either with biometrics or passcode) or was connected to an accessory or computer. If a full seven days (168 hours) elapse [sic] since the last time iOS saved one of these events, the Lightning port is entirely disabled,” Thomas wrote in a blog post published in a customer-only portal, which Motherboard obtained. “You cannot use it to sync or to connect to accessories. It is basically just a charging port at this point. This is termed USB Restricted Mode and it affects all devices that support iOS 11.3.”

Whether that’s real or marketing, we don’t know.

Posted on June 26, 2018 at 9:38 AM • View Comments

Perverse Vulnerability from Interaction between 2-Factor Authentication and iOS AutoFill

Apple is rolling out an iOS security usability feature called Security code AutoFill. The basic idea is that the OS scans incoming SMS messages for security codes and suggests them in AutoFill, so that people can use them without having to memorize or type them.

Sounds like a really good idea, but Andreas Gutmann points out an application where this could become a vulnerability: when authenticating transactions:

Transaction authentication, as opposed to user authentication, is used to attest the correctness of the intention of an action rather than just the identity of a user. It is most widely known from online banking, where it is an essential tool to defend against sophisticated attacks. For example, an adversary can try to trick a victim into transferring money to a different account than the one intended. To achieve this the adversary might use social engineering techniques such as phishing and vishing and/or tools such as Man-in-the-Browser malware.

Transaction authentication is used to defend against these adversaries. Different methods exist but in the one of relevance here—which is among the most common methods currently used—the bank will summarise the salient information of any transaction request, augment this summary with a TAN tailored to that information, and send this data to the registered phone number via SMS. The user, or bank customer in this case, should verify the summary and, if this summary matches with his or her intentions, copy the TAN from the SMS message into the webpage.

This new iOS feature creates problems for the use of SMS in transaction authentication. Applied to 2FA, the user would no longer need to open and read the SMS from which the code has already been conveniently extracted and presented. Unless this feature can reliably distinguish between OTPs in 2FA and TANs in transaction authentication, we can expect that users will also have their TANs extracted and presented without context of the salient information, e.g. amount and destination of the transaction. Yet, precisely the verification of this salient information is essential for security. Examples of where this scenario could apply include a Man-in-the-Middle attack on the user accessing online banking from their mobile browser, or where a malicious website or app on the user’s phone accesses the bank’s legitimate online banking service.

This is an interesting interaction between two security systems. Security code AutoFill eliminates the need for the user to view the SMS or memorize the one-time code. Transaction authentication assumes the user read and approved the additional information in the SMS message before using the one-time code.

Posted on June 20, 2018 at 6:51 AM • View Comments

New iPhone OS May Include Device-Unlocking Security

iOS 12, the next release of Apple’s iPhone operating system, may include features to prevent someone from unlocking your phone without your permission:

The feature essentially forces users to unlock the iPhone with the passcode when connecting it to a USB accessory everytime the phone has not been unlocked for one hour. That includes the iPhone unlocking devices that companies such as Cellebrite or GrayShift make, which police departments all over the world use to hack into seized iPhones.

“That pretty much kills [GrayShift’s product] GrayKey and Cellebrite,” Ryan Duff, a security researcher who has studied iPhone and is Director of Cyber Solutions at Point3 Security, told Motherboard in an online chat. “If it actually does what it says and doesn’t let ANY type of data connection happen until it’s unlocked, then yes. You can’t exploit the device if you can’t communicate with it.”

This is part of a bunch of security enhancements in iOS 12:

Other enhancements include tools for generating strong passwords, storing them in the iCloud keychain, and automatically entering them into Safari and iOS apps across all of a user’s devices. Previously, standalone apps such as 1Password have done much the same thing. Now, Apple is integrating the functions directly into macOS and iOS. Apple also debuted new programming interfaces that allow users to more easily access passwords stored in third-party password managers directly from the QuickType bar. The company also announced a new feature that will flag reused passwords, an interface that autofills one-time passwords provided by authentication apps, and a mechanism for sharing passwords among nearby iOS devices, Macs, and Apple TVs.

A separate privacy enhancement is designed to prevent websites from tracking people when using Safari. It’s specifically designed to prevent share buttons and comment code on webpages from tracking people’s movements across the Web without permission or from collecting a device’s unique settings such as fonts, in an attempt to fingerprint the device.

The last additions of note are new permission dialogues macOS Mojave will display before allowing apps to access a user’s camera or microphone. The permissions are designed to thwart malicious software that surreptitiously turns on these devices in an attempt to spy on users. The new protections will largely mimic those previously available only through standalone apps such as one called Oversight, developed by security researcher Patrick Wardle. Apple said similar dialog permissions will protect the file system, mail database, message history, and backups.

Posted on June 12, 2018 at 6:23 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.