Quasar Linux (QLNX) is a sophisticated Linux implant that combines rootkit, backdoor, and credential-stealing capabilities. It dynamically compiles rootkit shared objects and PAM backdoor modules on target hosts using gcc. The malware runs in-memory, deletes original binaries, wipes logs, spoofs process names, and clears forensic environment variables. It uses seven persistence mechanisms including LD_PRELOAD, systemd, crontab, init.d scripts, XDG autostart, and .bashrc injection. Core components include: RAT core with 58-command framework, dual-layer rootkit (userland LD_PRELOAD and kernel-level eBPF), credential access layer, surveillance module, networking and lateral movement capabilities, execution and injection engine, and filesystem monitoring via inotify. The malware establishes fileless foothold and targets development environments including npm, PyPI, GitHub, AWS, Docker, and Kubernetes.