North Korean hackers associated with the BlueNoroff group have launched a new attack campaign, known as “Hidden Risk,” targeting macOS users in cryptocurrency and decentralized finance (DeFi) sectors. Discovered by cybersecurity firm SentinelOne, this campaign is designed to infect devices via a multi-stage malware that installs a backdoor on Apple systems. The attackers deploy fake cryptocurrency news in phishing emails to trick targets into downloading a malicious application disguised as a PDF. Once activated, the app secretly downloads and displays a decoy PDF to avoid suspicion while installing additional payloads to compromise the system.
The malware, written in Swift and disguised as a legitimate PDF reader, uses a novel persistence technique to remain undetected. SentinelOne researchers noted that “Hidden Risk” exploits the zshenv configuration file, which bypasses macOS’s standard security notifications for background items. This method effectively circumvents alerts introduced by Apple in macOS Ventura to notify users of persistent software installed on their devices, specifically those that use LaunchAgents and LaunchDaemons. By abusing zshenv, the malware avoids triggering any of these notifications, enhancing its stealth.
BlueNoroff’s campaign infrastructure uses multiple domains and platforms, such as Namecheap, Quickpacket, and Hostwinds, for increased legitimacy and effectiveness. The threat actors have gone as far as acquiring valid Apple developer accounts to notarize the malware, leveraging Apple’s security standards to make their applications appear authentic. This tactic reflects the group’s adaptability and sophisticated approach to bypassing the increasingly rigorous security controls applied to macOS applications. SentinelOne’s researchers also observed a shift in BlueNoroff’s tactics, moving away from “grooming” targets through social media to more direct email phishing attacks.
This campaign is part of a broader North Korean initiative targeting cryptocurrency sectors worldwide, with attacks seen in other operations by the Lazarus Group, known for its Wagemole and Contagious Interview campaigns. These efforts have sought to gain remote access to systems, steal funds, and bypass financial sanctions through both sophisticated social engineering and malware deployment. As North Korean hackers continue to evolve their methods, cryptocurrency firms remain under significant threat, facing risks of data breaches, unauthorized access, and financial theft on a global scale.
