CAS-004 Security Engineering — Timed 20 Questions

Question 1

An organization wants to implement a privileged access management (PAM) solution to manage administrative credentials. They require that administrators request temporary access to privileged accounts and that these credentials are automatically rotated after each use. Which PAM approach best meets these requirements?

20 minute time limit — choose an answer to begin.

Accepted Answer

Just-in-time access provisioning with credential rotation. Just-in-time (JIT) access provisioning grants temporary privileges that expire after a defined period, and automatic credential rotation ensures that each session uses new credentials, meeting the requirement for temporary access and automatic rotation. Password vaulting may involve checkout but often does not force rotation, and session management primarily focuses on monitoring rather than credential rotation. Break-glass accounts are intended for emergency access only, not for routine administrative use.

Answer

Password vaulting with checkout

Answer

Privileged account session management

Answer

Break-glass account procedures

Question 2

A company is migrating from RSA to elliptic curve cryptography for digital signatures. They require a signature algorithm that provides at least 128 bits of security strength and is resistant to quantum computing attacks in the foreseeable future. Which TWO algorithms meet these requirements? (Select TWO.)

Accepted Answer

DSA 3072. DSA 3072 and RSA 4096 are both considered to provide at least 128 bits of security strength. Although all classical public-key algorithms are theoretically vulnerable to quantum attacks via Shor's algorithm, in practice DSA and RSA with large key sizes are currently believed to be more resistant to quantum computing attacks in the foreseeable future compared to elliptic curve algorithms like ECDSA and Ed25519, which are more susceptible due to their smaller key sizes and the efficiency of Shor's algorithm on elliptic curves.

Answer

ECDSA P-256

Answer

Ed25519

Answer

ECDSA P-384

Question 3

An organization wants to implement passwordless authentication using FIDO2/WebAuthn. Which of the following best describes the primary security advantage of this approach over traditional password-based authentication?

Accepted Answer

It prevents phishing by using cryptographic keys bound to the origin. FIDO2/WebAuthn prevents phishing because the private key is bound to the origin (the specific website domain). During authentication, the browser verifies that the origin matches the one registered with the key pair. This means even if a user is tricked into visiting a fake site, the authentication will fail because the origin does not match, effectively thwarting phishing attacks.

Answer

It eliminates the need for multi-factor authentication

Answer

It allows users to reuse the same password across services

Answer

It requires a hardware token for every login

Question 4

A security architect is designing a new authentication system for a high-security environment. The system must support passwordless authentication while providing strong protection against phishing attacks. Which of the following protocols best meets these requirements?

Accepted Answer

FIDO2/WebAuthn. FIDO2/WebAuthn uses public key cryptography and is designed to resist phishing; it supports passwordless authentication. TOTP/HOTP are time-based and can be phished. X.509 certificates are not inherently passwordless. Kerberos requires passwords or tickets.

Answer

Kerberos with PKINIT

Answer

TOTP/HOTP

Answer

X.509 certificates with smart cards

Question 5

A security engineer is reviewing a PKI deployment where the root CA is kept offline. The issuing CA signs certificates for internal applications. Recently, a subordinate CA was compromised, and the engineer needs to revoke all certificates issued by that CA. Which of the following is the most efficient method to revoke these certificates?

Accepted Answer

Publish a CRL from the compromised CA listing all certificates it issued. The best method is to use a CRL issued by the compromised CA, marking all its unexpired certificates as revoked. Revoking the CA certificate itself invalidates all certificates issued by it, including valid ones. Distributing a new CRL from the root CA would require the root to be online. Individual certificate revocation is inefficient.

Answer

Re-issue all certificates from a different issuing CA without revocation

Answer

Use OCSP to individually check and revoke each certificate

Answer

Revoke the compromised CA certificate and issue a new CRL from the root CA

Question 6

A company requires a cryptographic hash function for integrity verification of large files. The solution must be resistant to length extension attacks and provide high performance. Which of the following is the best choice?

Accepted Answer

SHA-3. SHA-3 is not vulnerable to length extension attacks and offers good performance. SHA-256 is vulnerable to length extension. BLAKE3 is fast but less standardized. MD5 is broken and insecure.

Answer

BLAKE3

Answer

SHA-256

Answer

MD5

Question 7

An organization is implementing IPsec VPNs between sites. The security team wants to ensure data integrity and authentication but is less concerned about confidentiality for this particular link. Which IPsec protocol and mode should they use?

Accepted Answer

AH in tunnel mode. AH provides authentication and integrity without encryption. Transport mode is used for end-to-end communication, while tunnel mode is for gateway-to-gateway. Since this is between sites (gateways), tunnel mode is appropriate. AH in transport mode is for host-to-host. ESP provides confidentiality. AH in tunnel mode is correct.

Answer

ESP in tunnel mode

Answer

AH in transport mode

Answer

ESP in transport mode

Question 8

A security analyst is configuring a TPM 2.0 for a new fleet of laptops. The requirement is to ensure that only authorized operating systems can boot and that any tampering with the boot process is detected. Which TPM feature should be used?

Accepted Answer

Measured boot with attestation. Measured boot records measurements of boot components in PCRs, and attestation allows a remote verifier to check these measurements. Secure boot only verifies signatures, not measurements. Sealed storage ties data to PCR values. Key attestation is for keys.

Answer

Secure boot

Answer

Sealed storage

Answer

Key attestation

Question 9

A web server is configured to use TLS 1.3. Which of the following is a key security benefit of TLS 1.3 over earlier versions?

Accepted Answer

Forward secrecy for all key exchanges. TLS 1.3 provides forward secrecy by default, meaning session keys are not compromised even if the server's long-term private key is compromised. 0-RTT is a performance feature but can be vulnerable to replay. Removed cipher suites is a cleanup. Certificate pinning is not part of TLS 1.3.

Answer

Removal of weak cipher suites

Answer

Support for 0-RTT handshake

Answer

Mandatory certificate pinning

Question 10

A security engineer is selecting an asymmetric encryption algorithm for a system that must provide non-repudiation and long-term security (at least 20 years). The system has limited computational resources. Which of the following is the best choice?

Accepted Answer

Ed25519. Ed25519 offers high security with small key sizes and efficient computation, and is suitable for long-term security. RSA 4096 is slower and has larger keys. ECDSA P-384 is secure but slower than Ed25519. DSA is older and less efficient.

Answer

RSA 4096

Answer

ECDSA P-384

Answer

DSA 3072

Question 11

A company is deploying IoT sensors that require secure firmware updates over the air (OTA). To ensure integrity and authenticity of the firmware, which of the following should be implemented?

Accepted Answer

Code signing with a trusted certificate. Code signing with digital signatures ensures firmware integrity and authenticity. Encryption alone does not guarantee authenticity. Hash verification ensures integrity but not authenticity. Secure boot ensures only signed firmware runs but does not protect the update process itself.

Answer

Secure boot on the device

Answer

Hash verification only

Answer

Encryption of the firmware image

Question 12

Which of the following certificate types is most appropriate for an organization that needs to validate the identity of individuals for email encryption and signing?

Accepted Answer

S/MIME certificate. S/MIME certificates are specifically designed for securing email. Client certificates are for authentication. Code signing is for software. DV certificates are for websites.

Answer

Domain Validation (DV) certificate

Answer

Client authentication certificate

Answer

Code signing certificate

Question 13

During a security assessment, an analyst discovers that an HSM used for key generation is FIPS 140-2 Level 2 compliant. The organization requires a higher level of physical security to prevent tampering. Which upgrade would best address this requirement?

Accepted Answer

Upgrade to FIPS 140-2 Level 3. FIPS 140-2 Level 3 requires tamper-evident coatings and physical security mechanisms. Level 4 is even higher but may be overkill. Moving to Level 2 is same. Level 1 has no physical security. Software-based TPM is not equivalent.

Answer

Implement a TPM 2.0 instead

Answer

Upgrade to FIPS 140-2 Level 4

Answer

Use a software-based key store

Question 14

A security administrator is hardening SSH access to a jump host. The requirement is to allow only key-based authentication and restrict the use of weak cryptographic algorithms. Which of the following configurations accomplishes this?

Accepted Answer

Set PubkeyAuthentication yes, PasswordAuthentication no, and configure Ciphers and MACs to strong algorithms only. Setting PubkeyAuthentication yes and PasswordAuthentication no enforces key-only access. Disabling weak ciphers and MACs ensures strong cryptographic algorithms are used. Option A permits password authentication with 'PasswordAuthentication yes'. Option C allows passwords. Option D allows keyboard-interactive, which can include passwords. Only Option B meets both requirements.

Answer

Set PermitRootLogin prohibit-password and PasswordAuthentication yes

Answer

Set PasswordAuthentication yes and use a strong password policy

Answer

Set AuthenticationMethods publickey,keyboard-interactive

Question 15

An organization is implementing a PKI with a three-tier hierarchy (root CA, intermediate CA, issuing CA). The security team wants to ensure that certificate revocation information is available quickly and efficiently. Which TWO mechanisms should they implement? (Select TWO.)

Accepted Answer

CRL distribution points (CRL DP). CRL and OCSP are standard revocation mechanisms. Certificate transparency (CT) logs are for auditing, not real-time revocation. Delta CRLs are more efficient for frequent updates. OCSP stapling reduces load on OCSP responders.

Answer

OCSP stapling

Answer

Delta CRLs

Answer

Certificate Transparency (CT) logs

Question 16

A security engineer is evaluating hardware security modules (HSMs) for key management. The HSM must support key generation, storage, and cryptographic operations without exposing private keys. Additionally, the solution must comply with FIPS 140-2 Level 3. Which THREE features are essential for this requirement? (Select THREE.)

Accepted Answer

Physical security mechanisms (e.g., locks, tamper switches). FIPS 140-2 Level 3 requires tamper-evident coatings, physical security, and cryptographic boundary. Key ceremony is a procedural control, not a feature of the HSM itself. Secure boot is for general computing. Multi-factor authentication is a user access control, not a core HSM feature.

Answer

Key ceremony support

Answer

Secure boot of the HSM firmware

Question 17

A security architect is designing a new web application that must meet strict data confidentiality and integrity requirements. The application will run in a cloud environment and must support low-latency operations. The architect is considering cipher suites for TLS 1.3. Which combination of algorithms would best meet these requirements?

Accepted Answer

ChaCha20-Poly1305 with ECDHE key exchange and Ed25519. ChaCha20-Poly1305 is a symmetric cipher that offers excellent performance on mobile and low-power devices, while providing authenticated encryption. ECDHE provides forward secrecy, and Ed25519 provides efficient authentication. AES-256-GCM is also good but ChaCha20 often performs better in software. RSA key exchange does not provide forward secrecy. SHA-256 is a hashing algorithm, not an encryption algorithm.

Answer

AES-128-CBC with HMAC-SHA256 and RSA-2048

Answer

ChaCha20-Poly1305 with static ECDH and SHA-384

Answer

AES-256-GCM with RSA key exchange and SHA-256

Question 18

An organization is implementing a PKI to issue certificates for internal applications. The security team wants to minimize the risk of compromise to the root CA. Which of the following is the BEST practice to protect the root CA?

Accepted Answer

Keep the root CA offline and store its private key in a hardware security module. Keeping the root CA offline and using a hardware security module (HSM) for key storage ensures its private key is never exposed to network threats. This is a standard best practice.

Answer

Delegate root CA responsibilities to a public CA

Answer

Install the root CA on a VM with strict firewall rules

Answer

Use a self-signed certificate for the root CA and distribute it manually

Question 19

A company is migrating its internal services to use SSH key-based authentication instead of passwords. The security policy requires using the strongest supported algorithms. The SSH server supports the following key exchange algorithms: diffie-hellman-group14-sha256, ecdh-sha2-nistp384, curve25519-sha256. Which algorithm should the administrator choose to meet the policy?

Accepted Answer

curve25519-sha256. Curve25519 (X25519) is the recommended elliptic curve for key exchange due to its strong security and performance advantages. It is considered more secure than NIST curves and traditional Diffie-Hellman.

Answer

ecdh-sha2-nistp384

Answer

diffie-hellman-group14-sha256

Answer

All three are equally strong

Question 20

A security auditor is reviewing the cryptographic controls of a financial application that processes transactions. The application uses digital signatures with RSA 4096 and SHA-256. The auditor recommends migrating to a stronger algorithm due to concerns about long-term security and quantum resistance. Which of the following would be the MOST appropriate replacement?

Accepted Answer

Ed25519. Ed25519 offers strong security, smaller keys, and better performance than RSA. It is also resistance to some side-channel attacks. While not quantum-resistant, it is a forward-looking choice. ECDSA P-384 is also strong but larger key sizes. SHA-3 is a hash function, not a signature algorithm.

Answer

SHA-3

Answer

ECDSA P-521

Answer

ECDSA P-256