By using tar with –checkpoint-action options, a specified action can be used after a checkpoint. This action could be a malicious shell script that could be used for executing arbitrary commands under the user who starts tar. “Tricking” root to use the specific options is quite easy, and that’s where the wildcard comes in handy.
These files work against a "tar *"
--checkpoint=1
--checkpoint-action=exec=sh shell.sh
shell.sh (your exploit code is here)