Password Cracking Techniques and Countermeasures ECSS Practice Questions (Page 5)

Questions 21–25

1. 21expert · hard

   A security analyst has captured a set of password hashes from a compromised server. The hashes are salted with a unique salt per user. The analyst has limited time and wants to crack as many passwords as possible. Which strategy is most effective?

   • AFocus on brute-force attacks for all users simultaneously
   • BRun a dictionary attack with a large wordlist and rule-based mutations, using the known salt for each hash
   • CAttempt to reverse the salt to recover the original password
   • DUse a rainbow table that includes the salts
   Reveal Solution Discussion Select an answer first
2. 22expert · hard

   A company has just experienced a data breach where the password hash database was stolen. The hashes are salted and use a strong algorithm. The security team must decide on countermeasures to mitigate the impact. The company has a large user base, and forcing an immediate password change for all users would cause significant operational disruption. Which countermeasure balances security and operational impact?

   • AForce password changes for all users immediately
   • BIncrease password complexity requirements going forward
   • CForce password changes only for users with weak passwords, and enable MFA for all users
   • DDo nothing and monitor for suspicious activity
   Reveal Solution Discussion Select an answer first
4. 23expert · hard

   A company is implementing a new password policy. The security team wants to prevent both online brute-force attacks and offline cracking of stolen hashes. The company has a large user base and wants to minimize user frustration. Which combination of countermeasures is most effective?

   • AUse a password blacklist and store passwords in plaintext
   • BUse a minimum password length of 8 characters and store passwords as salted SHA-256
   • CImplement account lockout after 5 failed attempts and use salted bcrypt for storage
   • DImplement multi-factor authentication and store passwords as unsalted MD5
   Reveal Solution Discussion Select an answer first
5. 24application · medium

   During a penetration test, a security analyst captures the following password hashes from a Linux system: 'root:$6$salt123$hashvalue...' and 'alice:$6$salt456$hashvalue...'. The analyst notices that both hashes use the SHA-512 crypt format with different salts. The analyst has a wordlist of 10 million common passwords and needs to test them against both accounts. Which attack technique is most appropriate for this scenario?

   • ABrute-force attack trying all combinations of 8 characters
   • BRainbow table attack using precomputed tables for SHA-512
   • CHybrid attack that appends numbers to each word in the wordlist
   • DDictionary attack that hashes each word with each salt and compares
   Reveal Solution Discussion Select an answer first
6. 25expert · hard

   A penetration tester is assessing a network and has captured NTLMv2 hashes from a Windows environment. The tester has access to a powerful GPU workstation and needs to crack these hashes. The hashes are known to be derived from passwords that follow a corporate policy requiring at least 8 characters with a mix of uppercase, lowercase, digits, and symbols. Which tool and attack strategy is most appropriate?

   • AUse Hydra to brute-force the NTLMv2 hashes online
   • BUse John the Ripper with a dictionary attack only
   • CUse rainbow tables for NTLMv2 hashes
   • DUse Hashcat with a mask attack targeting the known complexity requirements
   Reveal Solution Discussion Select an answer first