North Korean Phishing Campaign Uses GitHub as Covert C2 Against South Korean Firms

FortiGuard Labs reported a high-severity cyber espionage campaign linked to North Korean state-sponsored actors that targets organizations in South Korea with phishing emails carrying malicious Windows .lnk files disguised as PDF documents. When opened, the shortcut launches PowerShell and other native Windows scripting tools while showing a decoy document, then performs anti-analysis checks for tools including Wireshark, Fiddler, x64dbg, Procmon, and vmtoolsd. Researchers said the operation has been active since at least 2024 and has evolved from earlier, less-obfuscated variants associated with XenoRAT into more sophisticated samples that embed decoding logic and payload data directly in the shortcut file.

The malware establishes persistence through a Scheduled Task disguised as a technical paper and set to run every 30 minutes, then collects host data such as OS version, build number, process lists, and keep-alive logs. Operators used trusted GitHub accounts and private repositories as covert command-and-control and data-staging infrastructure, allowing malicious HTTPS traffic to blend with normal web activity while exfiltrating system information and retrieving follow-on instructions. Decoy filenames and metadata, including the "Hangul Document" naming convention, indicate deliberate targeting of South Korean companies and tradecraft aligned with clusters such as Kimsuky, APT37, and Lazarus.