010-160 Security And File Permissions Practice Test 4 — 15 Questions

Question 1

A junior administrator is troubleshooting a payroll application and runs 'ls -l /srv/payroll/run.sh'. The output shows '-rwxr-x--- 1 root finance 2048 Apr 10 09:14 /srv/payroll/run.sh'. A member of the 'marketing' group complains the script fails with 'Permission denied'. What is the most likely reason?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The marketing user is not the file owner and is not a member of the finance group, so the 'others' permission set applies and grants no access.. Linux evaluates exactly one permission class per access: owner if the caller's UID matches, otherwise group if any of the caller's groups matches the file's group, otherwise others. A marketing user matches neither owner nor group, so only the trailing '---' applies, producing the denial. Understanding this single-class evaluation is essential when diagnosing access complaints.

Answer

The script lacks the setuid bit, so it cannot run with root privileges and the kernel refuses execution for non-owners.

Answer

The 'others' class has write permission removed, and Linux requires write access on a file before it can be executed by a non-owner.

Answer

The execute bit is missing from the group class, so even finance members cannot run the script and the shell falls back to the others class.

Question 2

A shared project directory `/srv/team` is owned by user `lead` and group `team`. Team members must be able to create, edit, and delete each other's files, and every new file must automatically belong to the `team` group even when created by a user whose primary group is something else. The directory already has permissions `drwxrwx---`. Which single action accomplishes the group inheritance requirement?

Accepted Answer

chmod g+s /srv/team. The setgid bit on a directory is the standard mechanism for group inheritance. Once set, the kernel assigns the directory's group to every new file and subdirectory created within it, regardless of the creator's primary group. The sticky bit addresses deletion rights, and plain permission or ownership changes do not affect inheritance, so only the setgid approach meets the requirement.

Answer

chmod g+rwx /srv/team

Answer

chmod +t /srv/team

Answer

chown :team /srv/team

Question 3

A junior administrator needs to change the ownership of the file `/var/www/html/index.html` from user `deploy` to user `www-data`, while leaving the group ownership and all permission bits exactly as they are. Which command should be used?

Accepted Answer

chown www-data /var/www/html/index.html. The chown command changes file ownership, and when only a user name is supplied, the group is preserved. Using the colon form would change both owner and group, violating the requirement. The chmod and chgrp commands address permissions and group ownership respectively, so neither can fulfill the stated ownership change.

Answer

chgrp www-data /var/www/html/index.html

Answer

chown www-data:www-data /var/www/html/index.html

Answer

chmod www-data /var/www/html/index.html

Question 4

An administrator creates the directory /srv/dropbox and runs 'chmod 1777 /srv/dropbox'. Users report they can create files there, but cannot delete files created by other users. Which TWO statements correctly describe this configuration? (Choose two.)

Accepted Answer

The leading '1' sets the sticky bit, which restricts deletion or renaming of entries to the file's owner, the directory's owner, or root.. Mode 1777 on a directory combines world read/write/execute with the sticky bit. Write plus execute lets every user create entries, while the sticky bit limits deletion and renaming to the entry's owner, the directory's owner, or root. This is the classic shared drop-box pattern used by /tmp, balancing open creation with protection of existing files.

Answer

The sticky bit on a directory prevents any user other than root from writing new files into that directory.

Answer

Because the directory mode includes the execute bit for others, any user may delete any file within the directory.

Answer

The mode 1777 is invalid syntax, and the shell silently drops the leading digit, leaving the directory at 777.

Question 5

A user named alice has a primary group alice and is also a member of the group developers. She creates a new file named report.txt in her home directory. The umask is set to 022. What are the permissions of the newly created file?

Accepted Answer

-rw-r--r--. When a regular file is created, the kernel starts with a base mode of 666 (rw-rw-rw-) and applies the umask by clearing the bits specified. Umask 022 clears the write bits for group and others, leaving 644 (rw-r--r--). Thus the new file report.txt will have read and write for the owner, and read-only for group and others.

Answer

-rw-------

Answer

-rw-rw-r--

Answer

-rwxr-xr-x

Question 6

A technician must create a new local account named 'intern' on a Linux workstation and wants the command to also create the home directory and skeleton files automatically. Which command accomplishes this with a single invocation on a typical distribution?

Accepted Answer

useradd -m intern. The useradd utility provisions a new account entry in /etc/passwd and /etc/shadow, and the -m option additionally creates the home directory, copying default files from /etc/skel. It is the standard single-step method for adding a local user with an immediately usable environment, which is precisely what the scenario requires.

Answer

passwd -m intern

Answer

usermod -m intern

Answer

groupadd -m intern

Question 7

A security audit requires reviewing which local accounts exist on a Linux server, which of them have usable login shells, and which groups each account belongs to. Which TWO commands or files provide authoritative local account and group membership information? (Choose two.)

Accepted Answer

/etc/passwd. Local account records live in /etc/passwd, and local group definitions with supplementary members live in /etc/group. Reading them together reveals which accounts exist, what login shells they have, and which groups each belongs to. The shadow file covers passwords, skel provides templates, and nsswitch merely directs lookup order, so those three do not supply the required listings.

Answer

/etc/shadow

Answer

/etc/skel

Answer

/etc/nsswitch.conf

Question 8

A junior administrator needs to let a colleague in the accounting group read and write the shared report at /srv/reports/q3.csv, but no one outside that group should have any access. The file is currently owned by the administrator. Which command accomplishes this by changing only the group ownership to 'accounting'?

Accepted Answer

chgrp accounting /srv/reports/q3.csv. Group ownership is stored as a numeric GID in the file's inode and is changed with chgrp, or equivalently with chown using a colon separator. Using chgrp accounting changes only that metadata field, so the subsequent permission bits for the group category will apply to accounting members. Tools that edit user accounts or that only touch mode bits cannot perform this change.

Answer

chmod g=accounting /srv/reports/q3.csv

Answer

usermod -g accounting /srv/reports/q3.csv

Answer

chown accounting /srv/reports/q3.csv

Question 9

A junior administrator runs `chmod 4755 /usr/local/bin/maintenance.sh` on a shared production server. Later, a standard user executes the script and it performs actions that the user would not normally be permitted to do. Which statement explains this behavior?

Accepted Answer

The script runs with the effective user ID of the file owner, which is root in this case.. A leading 4 in a numeric mode sets the SUID bit on an executable. When run, the process takes on the effective user ID of the file's owner rather than the caller's. With root as owner, the script runs with root privileges, which explains why a standard user could perform restricted actions.

Answer

The script is automatically executed with the privileges of the user who last modified it.

Answer

The script inherits the group ownership of the directory in which it resides, granting elevated access.

Answer

The fourth digit enables the sticky bit, which allows any user to override file ownership checks.

Question 10

A user wants to view the permissions of all files in a directory, including hidden files, in a long listing format. Which command should they use?

Accepted Answer

ls -la. To view permissions of all files, including hidden ones, in a long listing format, the ls command needs both the -l and -a options. The -l option provides detailed information such as permissions, ownership, and size, while -a ensures that hidden files (those starting with a dot) are included. Combining them as ls -la achieves the desired output.

Answer

ls -l

Answer

ls -lh

Answer

ls -a

Question 11

An auditor asks how to confirm which groups the currently logged-in user belongs to, including supplementary groups, from a shell prompt. Which single command displays this information for the invoking user?

Accepted Answer

groups. The groups command, run without arguments, reports the group set for the current effective user, including the primary group and supplementary groups. That makes it the correct single command for confirming the invoking user's memberships during an audit, without needing to inspect /etc/group manually.

Answer

newgrp

Answer

groupmod

Answer

chgrp

Question 12

A server hosts a directory /srv/dropbox that many users write into. The administrator wants every new file created inside it to automatically belong to the group 'projects' rather than each creator's primary group, without changing anyone's account settings. Which action achieves this?

Accepted Answer

Run chmod g+s /srv/dropbox so new entries inherit the directory's group.. The setgid bit on a directory is the standard Linux mechanism for group inheritance: files and subdirectories created inside take the directory's group, and the bit is copied to new subdirectories. Setting it on a directory already group-owned by projects satisfies the requirement without editing /etc/passwd or /etc/group for individual users.

Answer

Run chgrp projects /srv/dropbox and rely on the default umask for inheritance.

Answer

Add every user to the projects group and set their primary group with newgrp.

Answer

Run chmod u+s /srv/dropbox so new entries inherit the directory's owner.

Question 13

A developer wants a shell script named `deploy.sh` located in the current directory to be runnable by typing `./deploy.sh`, but currently the command returns 'Permission denied' even though the file contains valid commands. Which command resolves the problem?

Accepted Answer

chmod u+x deploy.sh. Executing a file with ./ requires that the file carry execute permission for the invoking user, and chmod u+x grants exactly that to the owner. The other choices either set a mode without any execute bit, change ownership without adding execute, or attempt to elevate privileges around the missing bit. Only adding execute permission addresses the reported error directly.

Answer

sudo ./deploy.sh

Answer

chown root deploy.sh

Answer

chmod 644 deploy.sh

Question 14

A contractor needs to run a diagnostic script that requires reading a log file owned by `root` with mode `640` and group `adm`. The contractor's account `contractor` has primary group `contractor` but has been added as a supplementary member of `adm`. Which statement describes what will happen when the contractor attempts to read the file?

Accepted Answer

The read succeeds because supplementary group membership is honored, and the group read bit applies to the adm group.. Permission evaluation walks the owner, group, and others classes in order and stops at the first match. Because the contractor is a supplementary member of adm and the file grants read to group adm, the group class applies and access is allowed. Primary group switching or owner identity considerations do not change the outcome in this setup.

Answer

The read fails because the file is owned by root and the others class has no read permission.

Answer

The read fails because only the primary group is considered when evaluating the group permission class.

Answer

The read succeeds only if the contractor first runs newgrp adm to switch the primary group for the session.

Question 15

A developer runs `mkdir /srv/collab` on an ext4 filesystem, then runs `chmod 2775 /srv/collab` so that the directory is owned by root:devteam. Later, a member of the devteam group creates a file inside /srv/collab with their default umask of 022. Which group will own the newly created file?

Accepted Answer

The devteam group, because the setgid bit on the parent directory forces group inheritance.. The setgid bit on a directory makes new entries inherit the directory's group instead of the creator's primary group. Because the directory was set to 2775 with group devteam, any file created inside will belong to devteam while retaining the creator as user owner. The umask only strips permission bits and does not change group ownership.

Answer

No group, because the file is created without a group until chgrp is run explicitly.

Answer

The root group, because the parent directory is owned by root:devteam and ownership is copied.

Answer

The creating user's primary group, because file group ownership always mirrors the creator.