North Korea’s state-linked group, BlueNoroff, has been identified as the source of a new macOS malware known as ObjCShellz. This previously undocumented malware is part of the RustBucket campaign, which was unveiled earlier this year by Jamf Threat Labs. ObjCShellz is suspected to be a late-stage component of a multi-stage malware delivery operation carried out through social engineering tactics.
Furthermore, the BlueNoroff group, also known as APT38, is affiliated with the notorious Lazarus Group and specializes in financial cybercrime, often targeting banks and the cryptocurrency sector to evade sanctions and generate illegal profits.
This revelation follows Elastic Security Labs’ disclosure of the Lazarus Group’s use of a new macOS malware called KANDYKORN to target blockchain engineers. BlueNoroff’s macOS malware, RustBucket, is an AppleScript-based backdoor that retrieves a second-stage payload from an attacker-controlled server. The attacks are initiated by luring potential victims under the guise of offering investment advice or a job, and then infecting their systems with a decoy document. ObjCShellz, as the name suggests, is written in Objective-C and acts as a simple remote shell, executing commands sent from the attacker’s server.
While the exact targets of ObjCShellz remain unknown, the nature of these attacks suggests they are likely directed at companies within the cryptocurrency industry or those closely associated with it. The method of initial access for these attacks is yet to be determined, but it is suspected that the malware is delivered as a post-exploitation payload to run commands on compromised machines.
This discovery comes at a time when North Korean-sponsored groups, like Lazarus, are evolving and collaborating to share tools and tactics, making it challenging for cybersecurity experts to differentiate between them. The continuous development of bespoke malware for both Linux and macOS, along with the sharing of toolsets, signals the inevitability of further macOS malware campaigns.
