short_answer
medium
Understand
setuid-chain
2 points
Question 8. CSCD240-E1-B
Who owns /usr/bin/passwd in the ls -l line? Why does that matter for setuid?
Work the drill
Answer on paper or in a terminal before revealing the ideal answer.
Ideal answer
root. With setuid, the process runs with root's EUID, which is what grants it write access to /etc/shadow.
Misconception bank
Each row below is a plausible wrong answer, the thinking that produces it, and the remedy that corrects the misconception. These are the foundation of the multiple-choice framing and the targeted feedback a student receives after answering.
The invoker
Misconception. Misunderstands setuid direction — it elevates, not matches.
Remedy. Walk through: who runs it? Whose UID do they get? Why does that matter?
Authority mappings
Hover any chip for the mapping justification; click to open the authority record.
DCWF roles:
CE-121 Exploitation Analyst
DCWF tasks:
T0250
KU outcomes:
CO-M10-O1
Course-artifact links
Lectures
- CSCD240-S26-L05. Permissions part 1: ls -l anatomy, rwx, file types