Home Cyber Security News Shlayer Malware Exploited macOS Zero-Day To Bypass Apple Security

Shlayer Malware Exploited macOS Zero-Day To Bypass Apple Security

by Abeerah Hashim
Shlayer malware exploit macOS zero-day

Apple has recently released macOS Big Sur 11.3. This update addresses numerous security flaws including a zero-day under attack. As revealed, this zero-day attracted Shlayer malware to target vulnerable macOS devices via Gatekeeper bypass.

Shlayer Malware Exploiting macOS Zero-day

Apple security firm Jamf Protect has shared details of a serious macOS zero-day that a Shlayer malware variant actively exploits.

The vulnerability first caught the attention of researcher Cedric Owens who then reported it to Apple. It was a serious security issue that allowed an adversary with a malicious app to bypass Apple’s security check Gatekeeper.

Elaborating further on this issue, Patrick Wardle explained that a logic issue existed in the way macOS evaluates an app. Due to the bug, the system even allowed unsigned apps to run uninhibited. As stated,

Any script-based application that does not contain an Info.plist file will be misclassified as “not a bundle” and thus will be allowed to execute with no alerts nor prompts.

Wardle has shared how an app could exploit this flaw in his blog post.

Following this discovery, Wardle reached out to Jamf Protect that detected active exploitation of the bug by a Shlayer variant.

Shlayer first caught attention in June 2020 when researchers noticed it actively targeting macOS devices. The malware would easily bypass Apple’s underlying security mechanisms, such as Gatekeeper, Notarization, and File Quarantine.

And now, Jamf detected a Shlayer variant already designed in a way to exploit this logic issue CVE-2021-30657. Thus, the malware now requires no user interaction (such as the right-click limitation of the previous variant) to execute. All it takes is to trick a user into downloading the malicious file on the device and attempting to install it.

The attackers are currently distributing this malware via hacked and phishing websites appearing in Google SERPs.

Another Gatekeeper Also Fixed With Other Bugs

In addition to the above, one more Gatekeeper bypass bug has also received a fix with macOS Big Sur 11.3.

This vulnerability caught the attention of F-Secure researcher Rasmus Sten who then reported it to Apple.

Elaborating on this flaw in a blog post, Sten confirmed that this bug, CVE-2021-1810, did not suffer active exploitation.

While the researcher hasn’t shared more details of the bug for now due to security. Yet, here is a quick description of it.

Attackers can compromise users with this vulnerability by manipulating them into downloading a specially crafted .zip file (for example, via phishing) that exploits the vulnerability, allowing them to bypass macOS Gatekeeper’s code signature and notarization checks.

Alongside the two, Apple has also released tens of other security fixes with macOS Big Sur 11.3. Therefore, all users should ensure updating to this version at the earliest to avoid facing any cybersecurity mishap.

You may also like

Leave a Comment

Latest Hacking News

Privacy Preference Center


The __cfduid cookie is used to identify individual clients behind a shared IP address and apply security settings on a per-client basis.

cookie_notice_accepted and gdpr[allowed_cookies] are used to identify the choices made from the user regarding cookie consent.

For example, if a visitor is in a coffee shop where there may be several infected machines, but the specific visitor's machine is trusted (for example, because they completed a challenge within your Challenge Passage period), the cookie allows Cloudflare to identify that client and not challenge them again. It does not correspond to any user ID in your web application, and does not store any personally identifiable information.

__cfduid, cookie_notice_accepted, gdpr[allowed_cookies]


DoubleClick by Google refers to the DoubleClick Digital Marketing platform which is a separate division within Google. This is Google’s most advanced advertising tools set, which includes five interconnected platform components.

DoubleClick Campaign Manager: the ad-serving platform, called an Ad Server, that delivers ads to your customers and measures all online advertising, even across screens and channels.

DoubleClick Bid Manager – the programmatic bidding platform for bidding on high-quality ad inventory from more than 47 ad marketplaces including Google Display Network.

DoubleClick Ad Exchange: the world’s largest ad marketplace for purchasing display, video, mobile, Search and even Facebook inventory.

DoubleClick Search: is more powerful than AdWords and used for purchasing search ads across Google, Yahoo, and Bing.

DoubleClick Creative Solutions: for designing, delivering and measuring rich media (video) ads, interactive and expandable ads.



The _ga is asssociated with Google Universal Analytics - which is a significant update to Google's more commonly used analytics service. This cookie is used to distinguish unique users by assigning a randomly generated number as a client identifier. It is included in each page request in a site and used to calculate visitor, session and campaign data for the sites analytics reports. By default it is set to expire after 2 years, although this is customisable by website owners.

The _gat global object is used to create and retrieve tracker objects, from which all other methods are invoked. Therefore the methods in this list should be run only off a tracker object created using the _gat global variable. All other methods should be called using the _gaq global object for asynchronous tracking.

_gid works as a user navigates between web pages, they can use the gtag.js tagging library to record information about the page the user has seen (for example, the page's URL) in Google Analytics. The gtag.js tagging library uses HTTP Cookies to "remember" the user's previous interactions with the web pages.

_ga, _gat, _gid