A new malware tool named k4spreader, created by the Chinese mining gang “8220,” was discovered in June 2024. Written in Cgo and packed with a modified UPX packer, k4spreader is designed to install various types of malware, including the Tsunami DDoS botnet and PwnRig cryptominer. This multi-variant tool, which currently has three known variants, is noted for its persistence, self-update capabilities, and ability to download additional malicious payloads.
k4spreader exploits vulnerabilities such as CVE-2020-14882, JBoss_AS_3456_RCE, and YARN_API_RCE to spread. Passive DNS analysis has revealed that the command and control (C&C) servers associated with k4spreader also manage traffic for other shell scripts and mining pools used by the “8220” group. High volumes of traffic have been observed on active C&C servers, including dw.c4kdeliver.top, run.sck-dns.ws, and others.
The malware uses various methods to maintain persistence on infected systems. These include modifying the user’s bash startup file, creating system service scripts, and generating systemd service files. Each method ensures that the malware remains active even after a system reboot. The tool also has an updated version (v3) that enhances its evasion techniques and adds new functionalities such as logging and detecting runtime ports.
k4spreader hides its malicious payloads within an embedded ELF table, which can be accessed and executed via the k4spreader_utils_ExecuteEmbeddedBin() function. The Tsunami botnet and PwnRig miner are among the payloads dropped by this tool. It also has capabilities to disable firewalls, flush iptables rules, and remove suspicious processes, highlighting its complex and evolving nature.
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