An example could be that a user is allowed to run aria2c via sudo in the /etc/sudoers file (perhaps with certain restrictions described there). If that user's a

An example could be that a user is allowed to run aria2c via sudo in the /etc/sudoers file (perhaps with certain restrictions described there). If that user's account is compromised, the attacker could then potentially use the technique mentioned here to escalate to root or to the user as whom /etc/sudoers permits aria2c to be run, at least if the sudoers file didn't forbid the invocation that accomplish the escalation. One angle you could think about is "if I'm a system administrator writing an /etc/sudoers file and I want to allow users to do certain tasks, am I then inadvertently allowing them to do other completely unrelated tasks, perhaps in an entirely nonintuitive way"? Edit: a very nice example is https://news.ycombinator.com/item?id=20648960 https://news.ycombinator.com/item?id=20648960, downthread.