A system administrator wants to migrate from unsalted MD5 to a more secure password storage scheme. Which option best addresses the weaknesses of unsalted MD5?

Use bcrypt with a unique salt per user

During a penetration test, you retrieve a Linux shadow file. One entry contains a hash that starts with `$6$` followed by a 16-character salt and a long string of characters. Which hash algorithm and defensive property does this entry most likely represent?

MD5 crypt with a global salt, which slows down brute-force attempts

SHA-1 with no salt, which is vulnerable to rainbow-table attacks

bcrypt with a random salt, which provides built-in resistance to GPU cracking

SHA-512 crypt with a per-user salt, which prevents precomputed rainbow-table attacks

A development team is migrating a legacy user database to a new authentication service. The old system stored unsalted SHA-256 hashes, and the team wants to prevent rainbow table attacks without forcing all users to reset passwords. Which approach best meets this requirement?

Add a single global salt to all existing hashes and rehash

Rehash existing SHA-256 hashes with a unique salt per user and store the salt alongside

Encrypt the existing hashes with a static key

Store the existing SHA-256 hashes as-is and rely on password complexity policy

A penetration tester is attempting to crack a set of bcrypt hashes. The tester has a wordlist and a GPU. Which approach is most effective given that bcrypt is designed to be slow?

Use a hybrid attack that appends digits to each word

Use a brute-force attack over all possible 8-character passwords

Use a dictionary attack with the wordlist, accepting that bcrypt's slowness limits the number of guesses per second

GIAC Penetration Tester (GPEN)

Domain 3Objective 1

Password Formats and Hashes GPEN Practice Questions (Page 7)

Part of the Password Attacks and Credential Attacks domain, which makes up ~28% of our current practice bank. GIAC (SANS) does not publish an official question count, but from its 180-minute exam (~70–120 total, ~20–34 in this domain), expect 5–9 from this objective — we provide 39 practice questions to prepare you well beyond it. (estimate)

39questions here

8free pages

6concepts

Questions 31–35

31foundation · easy
Which property of a cryptographic hash function makes it infeasible to reverse the hash to find the original input?
Select an answer first
32application · medium
A system administrator wants to migrate from unsalted MD5 to a more secure password storage scheme. Which option best addresses the weaknesses of unsalted MD5?
Select an answer first
33application · medium
During a penetration test, you retrieve a Linux shadow file. One entry contains a hash that starts with `$6$` followed by a 16-character salt and a long string of characters. Which hash algorithm and defensive property does this entry most likely represent?
Select an answer first
34application · medium
A development team is migrating a legacy user database to a new authentication service. The old system stored unsalted SHA-256 hashes, and the team wants to prevent rainbow table attacks without forcing all users to reset passwords. Which approach best meets this requirement?
Select an answer first
35expert · hard
A penetration tester is attempting to crack a set of bcrypt hashes. The tester has a wordlist and a GPU. Which approach is most effective given that bcrypt is designed to be slow?
Select an answer first

Finished these 5 questions?

Review the revealed explanations, or continue through the curriculum.

Next 5 questions →Back to GPEN

Free Basic Practice is a study aid with revealable answers — not a scored exam. Examers.io is independent and not affiliated with or endorsed by GIAC (SANS). “GPEN” is a trademark of its owner, used for identification only.