essay
hard
Understand
setuid
2 points
Question 41. CSCD240-E1-A
Explain the setuid bit in 1-2 sentences using the term "effective user ID".
Work the drill
Answer on paper or in a terminal before revealing the ideal answer.
Ideal answer
When set, running the executable causes the process to have the effective user ID of the file's owner, not the invoker. This enables ordinary users to run programs like passwd that modify root-owned files.
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.
Setuid makes the file executable
Misconception. Confuses setuid with x bit.
Remedy. Distinguish: x = can run; setuid = runs AS owner.
Setuid elevates the user to root
Misconception. Only if owner is root. Not universal.
Remedy. Key phrase: "effective user ID of the owner", whoever that is.
Authority mappings
Hover any chip for the mapping justification; click to open the authority record.
DCWF roles:
CS-541 Vulnerability Assessment Analyst
DCWF tasks:
T0250
O*NET tasks:
SOC 15-1212.00: task 6SOC 15-1212.00: task 7SOC 15-1299.05: task 23SOC 15-1299.05: task 24
NCAE errors:
SMB Login / failure: SMB operation failed: [Errno.SMB Login / failure: SMB operation failed: [Errno.SMB Login / failure: SMB connection failed: proto.
Course-artifact links
Lectures
- CSCD240-S26-L05. Permissions part 1: ls -l anatomy, rwx, file types
CTF challenges
- 99 BONUS: Lecture Recall: What Does the S Stand For?