North Korean hackers target macOS users with Flutter malware

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Malware was most likely just an experiment, researchers claim

Hacker silhouette working on a laptop with North Korean flag on the background
(Image credit: Getty Images)
  • Experts found six malicious apps built for macOS
  • The Apple IDs used to sign the apps have been revoked
  • The malware was likely just an experiment

North Korean state-sponsored threat actors have been seen targeting macOS users with fake games and crypto tracking apps built with Flutter.

Cybersecurity researchers at Jamf recently found several apps on VirusTotal which seemed completely benign, yet connected to servers in North Korea, which was deemed “stage one” malware functionality.

There are two particularly interesting details about this malware. First - it was created with Flutter, an open source user interface (UI) software development kit created by Google. It allows developers to build natively compiled applications for mobile (iOS and Android), web, and desktop (Windows, macOS, Linux) from a single codebase.

Six malicious apps

One of the apps was called 'New Updates in Crypto Exchange (2024-08-28).app', and others were labeled in a similar manner. Yet, when opened, they ran open-source minesweeper games and similar.

Flutter, which uses the Dart programming language, provides obfuscation to the malicious code by design, the researchers said. Therefore, the malware was not that easy to spot (hence appearing as benign in VirusTotal).

The second interesting detail is that the apps were signed and notarized by a legitimate Apple developer ID, which means that at some point, they passed Apple’s security checks.

Jamf found a total of six apps, five of which were signed by a working Apple developer ID. It has been revoked in the meantime.

Yet, the researchers believe that the apps were never meant to be a part of an actual hacking campaign, and that they only served as an experiment.

“The malware discovered in this blog shows strong signs that it is likely testing for greater weaponization,” they added. “This could perhaps be an attempt to see if a properly signed app with malicious code obscured within a dylib could get approved by Apple’s notarization server, as well as slide under the radar of antivirus vendors.”

Via BleepingComputer

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Sead Fadilpašić

Sead is a seasoned freelance journalist based in Sarajevo, Bosnia and Herzegovina. He writes about IT (cloud, IoT, 5G, VPN) and cybersecurity (ransomware, data breaches, laws and regulations). In his career, spanning more than a decade, he’s written for numerous media outlets, including Al Jazeera Balkans. He’s also held several modules on content writing for Represent Communications.