Hackers Target macOS Users with Malicious Ads Spreading Stealer Malware

Malicious ads and bogus websites are acting as a conduit to deliver two different stealer malware, including Atomic Stealer, targeting Apple macOS users.

The ongoing infostealer attacks targeting macOS users may have adopted different methods to compromise victims' Macs, but operate with the end goal of stealing sensitive data, Jamf Threat Labs said in a report published Friday.

One such attack chain targets users searching for Arc Browser on search engines like Google to serve bogus ads that redirect users to look-alike sites ("airci[.]net") that serve the malware.

"Interestingly, the malicious website cannot be accessed directly, as it returns an error," security researchers Jaron Bradley, Ferdous Saljooki, and Maggie Zirnhelt said. "It can only be accessed through a generated sponsored link, presumably to evade detection."

The disk image file downloaded from the counterfeit website ("ArcSetup.dmg") delivers Atomic Stealer, which is known to request users to enter their system passwords via a fake prompt and ultimately facilitate information theft.

Jamf said it also discovered a phony website called meethub[.]gg that claims to offer a free group meeting scheduling software, but actually installs another stealer malware capable of harvesting users' keychain data, stored credentials in web browsers, and information from cryptocurrency wallets.

Much like Atomic stealer, the malware – which is said to overlap with a Rust-based stealer family known as Realst – also prompts the user for their macOS login password using an AppleScript call to carry out its malicious actions.

Attacks leveraging this malware are said to have approached victims under the pretext of discussing job opportunities and interviewing them for a podcast, subsequently asking them to download an app from meethub[.]gg to join a video conference provided in the meeting invites.

"These attacks are often focused on those in the crypto industry as such efforts can lead to large payouts for attackers," the researchers said. "Those in the industry should be hyper-aware that it's often easy to find public information that they are asset holders or can easily be tied to a company that puts them in this industry."

The development comes as MacPaw's cybersecurity division Moonlock Lab disclosed that malicious DMG files ("App_v1.0.4.dmg") are being used by threat actors to deploy a stealer malware designed to extract credentials and data from various applications.

This is accomplished by means of an obfuscated AppleScript and bash payload that's retrieved from a Russian IP address, the former of which is used to launch a deceptive prompt (as mentioned above) to trick users into providing the system passwords.

"Disguised as a harmless DMG file, it tricks the user into installation via a phishing image, persuading the user to bypass macOS's Gatekeeper security feature," security researcher Mykhailo Hrebeniuk said.

The findings are yet another indication that macOS environments are increasingly under threat from stealer attacks, with some strains even boasting of sophisticated anti-virtualization techniques by activating a self-destructing kill switch to evade detection.

In recent weeks, malvertising campaigns targeting Windows users have also been observed pushing the FakeBat loader (aka EugenLoader) and other information stealers like Rhadamanthys via a Go-based loader through decoy sites for popular software such as Notion and PuTTY.