macOS High Sierra Vulnerability Allegedly Allows Malicious Third-Party Apps to Access Plaintext Keychain Data

macOS High Sierra, released to the public today, could be impacted by a major security flaw that could allow a hacker to steal the usernames and passwords of accounts stored in Keychain.

As it turns out, unsigned apps on macOS High Sierra (and potentially earlier versions of macOS) can allegedly access the Keychain info and display plaintext usernames and passwords without a user's master password.

Security researcher and ex-NSA analyst Patrick Wardle tweeted about the vulnerability early this morning and shared a video of the exploit in action.


For this vulnerability to work, a user needs to download malicious third-party code from an unknown source, something Apple actively discourages with warnings about apps downloaded outside of the Mac App Store or from non-trusted developers. In fact, Apple does not even allow apps from non-trusted developers to be downloaded without explicitly overriding security settings.

As demonstrated in the video above, Wardle created a proof-of-concept app called "keychainStealer" that was able to access plaintext passwords stored in Keychain for Twitter, Facebook, and Bank of America. Wardle spoke to Forbes about the vulnerability and said it's actually not hard to get malicious code running on a Mac even with Apple's protections in place.

keychainpasswordexploit

"Without root priveleges, if the user is logged in, I can dump and exfiltrate the keychain, including plaintext passwords," Wardle told Forbes. "Normally you are not supposed to be able do that programmatically."

"Most attacks we see today involve social engineering and seem to be successful targeting Mac users," he added. "I'm not going to say the [keychain] exploit is elegant - but it does the job, doesn't require root and is 100% successful."

Wardle has not provided the full exploit code for malicious entities to take advantage of, and he believes Apple will patch the problem in a future update.

As Wardle has not released the full exploit code, it has not been double-checked by MacRumors or another source, so full details on the vulnerability are not known just yet.

Apple has not yet responded to requests for comment about the potential vulnerability.

Related Forum: macOS High Sierra

Top Rated Comments

DblHelix Avatar
85 months ago
Would have been great if he contacted Apple before the OS was released. Just looking for attention. Jerk
Score: 58 Votes (Like | Disagree)
sequential Avatar
85 months ago
Would have been great if he contacted Apple before the OS was released. Just looking for attention. Jerk
1. Would have been even greater if Apple had ppl who found these kind of bugs themselves before release.
2. You don't know if he found this yesterday. But sure hate on the guy who might have prevented your bank account password from ending up in the wrong hands.
Score: 52 Votes (Like | Disagree)
bladerunner2000 Avatar
85 months ago
On release day. That's embarrassing.
Score: 38 Votes (Like | Disagree)
carlsson Avatar
85 months ago
OMG, to enable this software you have to enter System Preferences, answer YES on two dialogues, and also enter your password. Then it may STEAL your not encoded things stored in the keychain (by default everything is stored encoded). I think I'm going to Windows now. This is just too much!!!

/irony ended
Score: 34 Votes (Like | Disagree)
s15119 Avatar
85 months ago
sigh. don't download junk, don't jeopardize your computer. Common sense is the best anti-virus.
Score: 21 Votes (Like | Disagree)
bladerunner2000 Avatar
85 months ago
If he did find it yesterday, he should have disclosed it to Apple and given them 90 days to fix it.
He doesn't owe Apple anything. Just like Apple doesn't owe him anything. He did them a favour.
Score: 19 Votes (Like | Disagree)

Popular Stories

iPhone Home Screen Gradient Blank Spaces 1

Sources: iOS 18 Lets Apps Be Placed Anywhere on Home Screen Grid

Sunday March 24, 2024 1:33 pm PDT by
iOS 18 will give iPhone users greater control over Home Screen app icon arrangement, according to sources familiar with the matter. While app icons will likely remain locked to an invisible grid system on the Home Screen, to ensure there is some uniformity, our sources say that users will be able to arrange icons more freely on iOS 18. For example, we expect that the update will introduce...
reset password request iphone

Warning: Apple Users Targeted in Phishing Attack Involving Rapid Password Reset Requests

Tuesday March 26, 2024 4:34 pm PDT by
Phishing attacks taking advantage of Apple's password reset feature have become increasingly common, according to a report from KrebsOnSecurity. Multiple Apple users have been targeted in an attack that bombards them with an endless stream of notifications or multi-factor authentication (MFA) messages in an attempt to cause panic so they'll respond favorably to social engineering. An...
iPad Pro 2024 Landscape Camera Feature

New iPad Pro Again Rumored to Feature Landscape Front-Facing Camera

Monday March 25, 2024 5:43 am PDT by
The next-generation iPad Pro will feature a landscape-oriented front-facing camera for the first time, according to the Apple leaker known as "Instant Digital." Instant Digital reiterated the design change earlier today on Weibo with a simple accompanying 2D image. The post reveals that the entire TrueDepth camera array will move to the right side of the device, while the microphone will...
sonoma desktop wwdc

Apple Releases macOS Sonoma 14.4.1 With Fix for USB Hub Bug

Monday March 25, 2024 10:10 am PDT by
Apple today released macOS Sonoma 14.4.1, a minor update for the macOS Sonoma operating system that launched last September. macOS Sonoma 14.4.1 comes three weeks after macOS Sonoma 14.4. The ‌‌‌‌macOS Sonoma‌‌ 14.4‌.1 update can be downloaded for free on all eligible Macs using the Software Update section of System Settings. There's also a macOS 13.6.6 release for those who...
Generic iOS 18 Feature Purple

iOS 18 Will Finally Bring This Android Feature to iPhone

Monday March 25, 2024 6:42 am PDT by
iOS 18 will allow iPhone users to place app icons anywhere on the Home Screen grid, according to sources familiar with development of the software update. This basic feature has long been available on Android smartphones. While app icons will likely remain locked to an invisible grid system on the Home Screen, our sources said that users will be able to arrange icons more freely on iOS 18....
iphone reasons to upgrade

Apple Outlines 'Reasons to Upgrade' Your iPhone on New Website

Monday March 25, 2024 12:53 pm PDT by
Apple today added a "Why Upgrade" section to its website, which is aimed at encouraging customers with older iPhones to upgrade to a newer model. The website allows customers to compare the iPhone 11, 11 Pro, 11 Pro Max, 12, 12 mini, 12 Pro, and 12 Pro Max to the iPhone 15, iPhone 15 Plus, iPhone 15 Pro, or iPhone 15 Pro Max. Each comparison shows what new features someone with an older...
maxresdefault

Apple Announces WWDC 2024 Event for June 10 to 14

Tuesday March 26, 2024 10:02 am PDT by
Apple today announced that its 35th annual Worldwide Developers Conference is set to take place from Monday, June 10 to Friday, June 14. As with WWDC events since 2020, WWDC 2024 will be an online event that is open to all developers at no cost. Subscribe to the MacRumors YouTube channel for more videos. WWDC 2024 will include online sessions and labs so that developers can learn about new...