Dirty COW

Dirty COW CVE-2016-5195: How a 2016 Linux Kernel Race Condition Still Enables Privilege Escalation in Embedded Systems

The 2016 Linux kernel vulnerability CVE-2016-5195, known as Dirty COW, allowed local users to bypass copy-on-write protections and modify read-only memory mappings through a race condition involving writes to /proc/self/mem and madvise calls. Although patched in supported distributions years ago, the flaw persists in older kernels running on routers, cameras, and industrial controllers that receive infrequent firmware updates. Public exploits often target /etc/passwd or SUID binaries for root access, but success depends heavily on the presence of login mechanisms, BusyBox applets, and suitable binaries in the target environment. When standard targets are absent, attackers may pivot to overwriting vDSO functions in process memory to inject code executed by higher-privileged processes. The article explains why ready-made PoCs frequently fail on minimal BusyBox-based systems and outlines the checks required for architecture, ABI, vDSO symbols, and payload compatibility. It also references the practical exercise Strange And Dirty on the free White Hacker course for hands-on adaptation of the exploit chain.