Phase 7: Dirty COW (CVE-2016-5195) FULL module — old-systems coverage
The iconic 2016 LPE. Fills the 10-year coverage gap (now spanning
2016 → 2026): RHEL 6/7, Ubuntu 14.04, Ubuntu 16.04, embedded boxes,
IoT — many still in production with kernels predating the 4.9 fix.
- modules/dirty_cow_cve_2016_5195/iamroot_modules.{c,h}:
- kernel_range: backport thresholds for 2.6 / 3.2 / 3.10 / 3.12 /
3.16 / 3.18 / 4.4 / 4.7 / 4.8 / mainline 4.9
- dirty_cow_write(): Phil-Oester-style two-thread race
- mmap /etc/passwd MAP_PRIVATE (writes go COW)
- writer thread: pwrite to /proc/self/mem at COW page offset
- madviser thread: madvise(MADV_DONTNEED) to drop COW copy
- poll-read /etc/passwd via separate fd to check if payload landed
- 3-second timeout (race usually wins in ms on vulnerable kernels)
- dirty_cow_exploit(): getpwuid → find_passwd_uid_field → race
→ execlp(su)
- dirty_cow_cleanup(): POSIX_FADV_DONTNEED + drop_caches
- Auditd rule: /proc/self/mem writes + madvise MADV_DONTNEED
- Sigma rule: non-root /proc/self/mem open → high
- Makefile: -lpthread added to LDFLAGS for the binary link.
- iamroot.c + core/registry.h wired.
- CVES.md row added with detailed status; legend updated.
Verified end-to-end on kctf-mgr (6.12.86 — patched):
iamroot --scan → 'dirty_cow: kernel is patched' (OK)
iamroot --exploit dirty_cow --i-know
→ 'detect() says not vulnerable; refusing'
Module count = 12.
leviathan
cb39cc5119