CAS-004 Security Engineering Practice Test 8 — 15 Questions

Question 1

A security analyst is reviewing TLS 1.3 configuration for a web server. The analyst wants to ensure that the configuration provides forward secrecy and prevents the reuse of session keys. Which of the following is a characteristic of TLS 1.3 that supports these goals?

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

Accepted Answer

Use of ephemeral Diffie-Hellman key exchange. TLS 1.3 mandates the use of ephemeral Diffie-Hellman key exchange (DHE or ECDHE) for all handshakes, which provides forward secrecy by generating a unique session key for each session that cannot be derived from the server's long-term private key. This ensures that even if the server's private key is compromised later, past session keys remain secure and cannot be reused.

Answer

0-RTT session resumption

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Support for static RSA key exchange

Answer

Removal of CBC mode cipher suites

Question 2

A company wants to implement certificate pinning for its mobile application to prevent man-in-the-middle attacks. Which of the following is the BEST practice when implementing certificate pinning?

Accepted Answer

Pin the public key of the server certificate. Pinning the public key rather than the entire certificate allows for certificate renewal without invalidating the pin.

Answer

Disable certificate pinning after the first successful connection

Answer

Pin the root CA certificate only

Answer

Pin the entire certificate chain

Question 3

A security engineer is configuring SSH for a jump host used to access critical servers. The engineer wants to restrict the cryptographic algorithms to the most secure options. Which of the following should be DISABLED?

Accepted Answer

Diffie-Hellman group-exchange with SHA-1. Diffie-Hellman group exchange with SHA-1 uses the SHA-1 hash for key exchange integrity, and SHA-1 is cryptographically broken (collision attacks demonstrated) and deprecated by NIST. For a hardened jump host, this kex algorithm should be disabled in favor of SHA-2-based groups like diffie-hellman-group-exchange-sha256 or curve25519-sha256.

Answer

AES-256-CTR

Answer

Ed25519 for host keys

Answer

HMAC-SHA2-256

Question 4

Which of the following is a primary advantage of using ChaCha20-Poly1305 over AES-256-GCM in certain environments?

Accepted Answer

Faster performance on devices without AES-NI. ChaCha20-Poly1305 is designed to be faster in software that lacks AES hardware acceleration, making it suitable for mobile devices.

Answer

Better hardware acceleration support

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Higher security margin

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Smaller ciphertext size

Question 5

A company is deploying a just-in-time (JIT) privileged access management solution. Which of the following BEST describes a key security benefit of JIT access?

Accepted Answer

It reduces the risk of lateral movement by limiting the duration of elevated privileges. JIT access grants temporary privileges only when needed, reducing the attack surface and the risk of standing privileges being misused.

Answer

It eliminates the need for multi-factor authentication

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It replaces the need for a break-glass account

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It provides continuous monitoring of all user actions

Question 6

An organization uses a TPM 2.0 for measured boot and attestation. Which TPM feature ensures that the boot process has not been tampered with by measuring each component before it executes?

Accepted Answer

Platform Configuration Registers (PCRs). Platform Configuration Registers (PCRs) store hash measurements of boot components. Any change in the boot sequence will result in different PCR values, alerting to tampering.

Answer

Endorsement Key (EK)

Answer

Secure boot

Answer

Sealed storage

Question 7

A security architect is designing a PKI for a large enterprise that issues certificates to thousands of users and devices. The architect wants to implement a mechanism to efficiently check certificate revocation status without requiring clients to download a full CRL. Which TWO technologies should be considered?

Accepted Answer

OCSP stapling. Option C (OCSP stapling) is correct because it lets the server obtain a signed, time-stamped OCSP response from the CA and present it during the TLS handshake, so clients get revocation status without contacting the OCSP responder themselves, reducing latency and load. Option D (Online Certificate Status Protocol, OCSP) is correct because it is the standard protocol for querying a responder about a single certificate's revocation status, returning good, revoked, or unknown, which avoids downloading an entire CRL. Option A (CRL distribution points) is not appropriate here because it points clients to full CRLs, which is exactly the bulk-download behavior the architect wants to avoid. Option B (certificate transparency logs) is unrelated to revocation checking; CT logs provide public auditability of issued certificates, not revocation status. Option E (delta CRL) still relies on CRL downloads (a base CRL plus deltas), so it does not meet the goal of avoiding full CRL retrieval.

Answer

CRL distribution points

Answer

Certificate transparency logs

Answer

Delta CRL

Question 8

A company is migrating its legacy VPN to use IPsec with IKEv2. The security team wants to ensure the strongest possible security. Which THREE configuration options should be selected?

Accepted Answer

Use ECDSA P-384 for authentication. Option A (ECDSA P-384) is correct because elliptic-curve signatures at the 384-bit level provide roughly 192-bit security strength, far exceeding RSA-2048, and are well supported in IKEv2 for strong peer authentication. Option C (AES-256-GCM) is correct because AES-256 gives a 256-bit key and GCM is an AEAD mode that provides both confidentiality and integrity in a single efficient primitive, making it the strongest symmetric choice here. Option E (perfect forward secrecy via DHE) is correct because Diffie-Hellman ephemeral key exchange ensures that compromise of the long-term key cannot decrypt previously captured sessions, which is essential for 'strongest possible security' in an IKEv2 deployment. Option B (SHA-1) is not appropriate because SHA-1 is cryptographically broken for integrity and should be replaced by SHA-256 or stronger. Option D (IKEv1) is not appropriate because IKEv2 is more secure, more robust, and supports modern features like MOBIKE and stronger authentication methods.

Answer

Use SHA-1 for integrity

Answer

Use IKEv1 instead of IKEv2

Question 9

An IoT device manufacturer wants to ensure the security of over-the-air (OTA) firmware updates. Which TWO measures are essential to protect the update process?

Accepted Answer

Sign the firmware with a trusted code signing certificate. Option A is correct because signing the firmware with a trusted code signing certificate lets the device verify authenticity and integrity via the vendor's public key, ensuring the OTA image genuinely originates from the manufacturer and has not been tampered with. Option C is correct because a secure boot chain validates that signature against a hardware-rooted trust anchor before the update is applied, preventing malicious or corrupted firmware from ever executing. Together, signing plus signature verification in a secure boot chain form the essential cryptographic trust path for OTA updates. Option B is not sufficient because a simple checksum detects only accidental corruption, not deliberate tampering, since it is not cryptographically bound to a secret or key. Option D is wrong because a hardcoded key can be extracted from the device and reused by attackers, and encryption alone does not prove authenticity. Option E is wrong because permitting downgrades enables rollback attacks that reintroduce known vulnerabilities.

Answer

Use a simple checksum for integrity verification

Answer

Encrypt the firmware using a hardcoded key

Answer

Allow firmware downgrades to previous versions

Question 10

A security engineer is configuring a TLS 1.3 connection between a web server and client. Which feature is unique to TLS 1.3 and provides reduced latency for returning clients?

Accepted Answer

0-RTT. 0-RTT (zero round-trip time) resumption is a TLS 1.3 feature that lets a returning client send application data in the first flight using a previously established session ticket, eliminating the round trip needed for a full handshake. This reduces latency for repeat connections. It is unique to TLS 1.3 and not available in TLS 1.2.

Answer

Cipher suite negotiation

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Forward secrecy

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Mutual authentication

Question 11

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 uses public-key cryptography where the private key never leaves the authenticator, and the credential is cryptographically bound to the origin (relying party ID) during registration. This origin binding means a phishing site on a different domain cannot trigger the authenticator to produce a valid assertion, because the browser enforces the RP ID match. Even if a user is tricked into visiting a lookalike site, the signature will not validate against the legitimate server's expected origin.

Answer

It eliminates the need for multi-factor authentication

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It allows users to reuse the same password across services

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It requires a hardware token for every login

Question 12

A security architect is designing a PKI hierarchy for a large enterprise that issues certificates for internal users, devices, and code signing. Which of the following best practices should be implemented to minimize the impact of a CA compromise?

Accepted Answer

Implement a segmented CA hierarchy with offline root CA and separate issuing CAs for each purpose. Using a tiered CA hierarchy with a root CA that remains offline and issuing CAs for specific purposes limits exposure. If an issuing CA is compromised, only its certificates need to be revoked, and the root CA can issue a new subordinate CA.

Answer

Rely on certificate transparency logs to detect compromises

Answer

Keep the root CA online for immediate certificate revocation

Answer

Use a single CA for all certificate types to reduce complexity

Question 13

A company is deploying IoT sensors in a harsh environment. The sensors have limited processing power and memory. Which of the following cryptographic algorithms is most suitable for ensuring data confidentiality with minimal overhead?

Accepted Answer

ChaCha20-Poly1305. ChaCha20-Poly1305 is a stream cipher that is fast in software, especially on devices without AES hardware acceleration, and provides authenticated encryption with low overhead.

Answer

RSA-4096

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SHA-256

Answer

AES-256-GCM

Question 14

During a security audit, it is discovered that a critical server uses SSH with password authentication and supports weak key exchange algorithms. Which of the following is the most effective hardening step to prevent brute-force attacks and ensure forward secrecy?

Accepted Answer

Disable password authentication and restrict key exchange algorithms to curve25519-sha256. Disabling password authentication forces the use of key-based authentication, which is resistant to brute-force attacks. Restricting key exchange algorithms to those providing forward secrecy (e.g., Curve25519) ensures that session keys cannot be compromised even if the long-term private key is exposed.

Answer

Implement fail2ban to block IPs after failed attempts

Answer

Change the SSH port to a non-default high port

Answer

Use RSA keys with 4096-bit length

Question 15

A security administrator is implementing TPM 2.0 for secure boot and measured boot on new laptops. Which TWO capabilities does TPM 2.0 provide that are directly related to ensuring the integrity of the boot process? (Select TWO.)

Accepted Answer

Remote attestation to verify boot measurements. TPM 2.0 can produce a signed quote of PCR values that a remote verifier uses to attest that the boot chain matches expected measurements, directly ensuring boot-process integrity. Option B (Platform Configuration Registers (PCRs) for storing measurements) is correct because TPM 2.0 PCRs hold the cumulative hashes of boot components (firmware, bootloader, OS) that form the basis of measured boot and are the values attested in option A. Option C is not a TPM capability; UEFI Secure Boot enforcement is performed by UEFI firmware using signature databases (db, dbx, KEK, PK), though the TPM may record its state. Option D, sealed storage, protects encryption keys by binding them to PCR values, but it is a data-protection feature rather than a direct boot-integrity capability. Option E, RSA key generation for code signing, is a general cryptographic function and not specifically tied to ensuring boot-process integrity.

Answer

UEFI secure boot enforcement

Answer

Sealed storage to protect encryption keys

Answer

Generation of RSA keys for code signing