performance medium Apply harden 2 points

Question 11. CSCD240-E1-B

Remove setuid bit from /opt/app/runner without changing other permissions.

Work the drill

Answer on paper or in a terminal before revealing the ideal answer.

Ideal answer

chmod u-s /opt/app/runner

Acceptable alternatives: ["chmod 0755 /opt/app/runner"]

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.

chmod -s /opt/app/runner

Misconception. -s without u/g removes both setuid AND setgid.

Remedy. Be explicit: u-s for setuid only.

chmod 755 /opt/app/runner

Misconception. Works but leaves ambiguity — what if original had other bits set?

Remedy. Use u-s for surgical removal.

Authority mappings

Hover any chip for the mapping justification; click to open the authority record.

DCWF roles: IT-451 System Administrator

DCWF tasks: T0136

KU outcomes: CD-OSC-O4 CO-M9-O2

O*NET tasks: SOC 15-1212.00: task 6 SOC 15-1212.00: task 7 SOC 15-1244.00: task 1 SOC 15-1244.00: task 2 SOC 15-1299.05: task 23 SOC 15-1299.05: task 24

NCAE errors: WWW SSL / failure: Failed to connect to hostSMB Login / failure: SMB operation failed: [Errno.WWW Content / failure: Failed to connect to hostWWW Content / timeout: TimeoutWWW Content / failure: Website cannot be reachedWWW SSL / timeout: TimeoutSSH Login / failure: Failed to connect to host: IPSMB Login / failure: SMB operation failed: [Errno.WWW SSL / failure: [SSL] record layer failure (_s.SMB Login / failure: SMB connection failed: proto.SSH Login / partial: The following users failed t.SSH Login / partial: The following users failed t.

Course-artifact links

Lectures

CSCD240-S26-L06. Permissions part 2: chmod octal + symbolic, directory x bit