Selected Topics in Computer Security (CS 5473)

1. ls -l shows 'drwxr-xr-x 3 wei staff 512 Oct 29 20:24 custom-theme'. What can another member of the staff group do with it?

• List and enter the directory, but not add or delete files
• Add, delete and rename files inside the directory freely
• Nothing at all, since only the owner wei has any access
• Run it as a program, because the x bit makes it executable

2. ls -l shows '-rw-r--r-- 1 wei staff 1292 Nov 10 22:13 testcss.css'. A user who is neither wei nor in staff opens it. What may that user do?

• Read the file but not change it
• Read and change the file's contents
• Nothing, others get no permissions
• Execute it but not read its contents

3. A user types a command in a shell and a new process starts. What permissions does that new process normally get?

• Its parent's permissions, unless the parent deliberately gives it lower ones
• Root permissions, because the kernel creates every new process itself
• No permissions until the user logs in again with a separate password
• The permissions of init, because init is the root of the process tree