LFCS Question #489: Real Exam Question with Answer & Explanation

Question

Why is /etc/shadow not world readable if the passwords are stored in an encrypted fashion?

Options

• AThe encrypted passwords are still subject to brute force attacks.
• BThis is just for historical reasons.
• CThere is other information in the file that needs to be kept secret.
• DThe passwords can be decrypted by anyone with root access.

Explanation

The /etc/shadow file is not world-readable because even though passwords are cryptographically hashed, these hashes are still vulnerable to offline brute-force or dictionary attacks if exposed.

Common mistakes.

• B. The restricted permissions on /etc/shadow are a direct security measure against password cracking, not merely a historical remnant.
• C. While /etc/shadow contains other sensitive information like password aging details, the primary and most critical reason for its restricted access is the protection of password hashes from cracking attempts.
• D. Passwords stored in /etc/shadow are hashed, not encrypted, meaning they cannot be "decrypted" back to their original plaintext form by anyone, including root. Root can change passwords, but not reverse hashes.

Concept tested. /etc/shadow security principles

No community discussion yet for this question.