CAS-004 Security Engineering Practice Test 2 — 15 Questions

Question 1

A security architect is evaluating hardware security modules (HSMs) for a new PKI deployment. The HSM must be compliant with FIPS 140-2 Level 3. Which of the following is a requirement for Level 3 that distinguishes it from Level 2?

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

Accepted Answer

Identity-based authentication for operators. FIPS 140-2 Level 3 requires identity-based authentication for all operators, meaning each user must be uniquely identified and authenticated (e.g., via username/password, smart card, or biometric) before accessing cryptographic services. This is a key differentiator from Level 2, which only requires role-based authentication (e.g., a shared password for a role). Level 3 also mandates stronger physical security (tamper detection and response) and environmental failure protections, but identity-based authentication is the specific requirement that distinguishes it from Level 2.

Answer

Cryptographic boundary includes all critical components

Answer

Environmental failure protections

Answer

Physical security mechanisms that provide tamper evidence

Question 2

An organization uses a PKI with a three-tier hierarchy: root CA, issuing CA, and registration authority. The root CA is kept offline. An intermediate CA certificate must be renewed. Which of the following is the correct process?

Accepted Answer

The root CA signs the new intermediate CA certificate after being brought online.. The root CA signs the intermediate CA certificate. Since the root CA is offline, it must be brought online temporarily to sign the new intermediate certificate. The RA does not sign certificates; it handles verification requests. The intermediate CA cannot self-sign its own certificate.

Answer

The intermediate CA self-signs its new certificate.

Answer

The issuing CA signs the new intermediate CA certificate.

Answer

The registration authority signs the new intermediate CA certificate.

Question 3

During a security assessment, a penetration tester discovers that a smart card used for authentication is vulnerable to a timing attack. The card uses a cryptographic algorithm that has data-dependent timing variations. Which of the following algorithms is MOST likely being used on the smart card?

Accepted Answer

RSA with Chinese Remainder Theorem. RSA decryption (using CRT) is known to be vulnerable to timing attacks if not implemented with constant-time functions. AES is typically resistant if implemented correctly. SHA-256 is a hash function, not used for signing/decryption. ECDSA can be vulnerable to timing attacks if not constant-time, but RSA is more commonly associated with classic timing vulnerabilities.

Answer

ECDSA P-384

Answer

SHA-256

Answer

AES-256-CBC

Question 4

An organization is planning to deploy digital certificates for various use cases. Which TWO of the following certificate types are typically used for email security?

Accepted Answer

Client certificates. Option A (Client certificates) is correct because in email security they are used for S/MIME, where each user holds a personal certificate and private key to digitally sign outgoing messages and decrypt incoming encrypted mail, providing sender authentication and non-repudiation. Option D (S/MIME certificates) is correct because S/MIME is the standard protocol for email encryption and digital signing, and S/MIME certificates bind a user's email address to a public key so messages can be encrypted and signatures verified. Option B (Code signing certificates) is not for email; they sign software binaries to prove publisher integrity. Option C (Extended validation certificates) is not for email; EV certificates are TLS/server certificates with extended identity vetting for websites. Option E (Domain-validated certificates) is not for email; DV certificates only validate domain control and are used for TLS on servers, not for signing or encrypting individual email messages.

Answer

Code signing certificates

Answer

Extended validation (EV) certificates

Answer

Domain-validated (DV) certificates

Question 5

A company wants to implement certificate pinning for its mobile app to prevent man-in-the-middle attacks. Which approach is most secure and maintainable?

Accepted Answer

Pin the SHA-256 hash of the server's public key.. Pinning the public key hash rather than the certificate itself allows certificate rotation without updating the app, as long as the key pair remains the same.

Answer

Pin the entire certificate chain, including the root CA certificate.

Answer

Pin the Subject Public Key Info (SPKI) using base64 encoding.

Answer

Pin the issuing CA certificate only.

Question 6

During a PKI migration, the security team discovers that some internal clients do not support OCSP stapling but require online certificate status checking. Which alternative should be configured to minimize latency and ensure validity?

Accepted Answer

Use a local OCSP responder to handle revocation checks within the internal network.. OCSP stapling is not supported; traditional OCSP requests add latency. A locally hosted OCSP responder reduces network round trips compared to relying on external CAs.

Answer

Switch to self-signed certificates to avoid revocation checking altogether.

Answer

Configure clients to use CRLDP with a local CRL distribution point.

Answer

Disable CRL checking and rely on certificate expiration only.

Question 7

Which hashing algorithm is recommended for modern applications requiring high security and resistance to quantum computing threats, and offers improved performance over SHA-2?

Accepted Answer

SHA-3. SHA-3 is the latest NIST-standardized hash function, designed to be resistant to quantum attacks and offers a different structure from SHA-2, with good performance.

Answer

RIPEMD-160

Answer

MD5

Answer

SHA-256

Question 8

A security architect is designing a secure OTA update mechanism for IoT devices. Which TWO features are essential to ensure the integrity and authenticity of firmware updates?

Accepted Answer

Secure boot chain that verifies the signature of the update before installation. Option B is correct because a secure boot chain that verifies the update's signature before installation ensures the firmware image is authentic and has not been tampered with, establishing a root of trust from the bootloader through the running image. Option E is correct because a digital signature using ECDSA P-384 provides cryptographic integrity and authenticity: the vendor signs the firmware with a private key and the device verifies it with the corresponding public key, detecting any modification and confirming the source. Option A is not essential here because AES-256-CTR provides confidentiality, not integrity or authenticity, and CTR mode alone is malleable without an authentication tag. Option C is not essential because an HSM protects key storage but does not itself verify update integrity or authenticity, and it is a key-management control rather than the verification mechanism. Option D is not essential because compression only reduces transfer size and has no bearing on integrity or authenticity.

Answer

Firmware encryption with AES-256-CTR

Answer

Use of a hardware security module (HSM) on the device for key storage

Answer

Compression of the firmware image to reduce transfer size

Question 9

An organization is implementing a hardware security module (HSM) to protect cryptographic keys used for code signing. The HSM is required to meet a government standard for physical security and tamper resistance. Which FIPS 140 security level must the HSM achieve to provide tamper-evident coatings and tamper response mechanisms?

Accepted Answer

FIPS 140-2 Level 3. FIPS 140-2 Level 3 requires tamper-evident coatings and tamper response mechanisms that zeroize keys upon tampering. Level 2 requires tamper-evident coatings but no response, Level 4 is for extreme environments.

Answer

FIPS 140-2 Level 4

Answer

FIPS 140-2 Level 2

Answer

FIPS 140-2 Level 1

Question 10

A company is deploying a new authentication system that leverages FIDO2/WebAuthn. Security architects want to ensure that the private key never leaves the authenticator device. Which attack vector is mitigated by this approach?

Accepted Answer

Server-side database breach exposing credentials. FIDO2/WebAuthn ensures that the private key never leaves the authenticator device, so even if the server's database is breached, the attacker cannot obtain the private key. This mitigates the risk of server-side database breaches exposing credentials.

Answer

Man-in-the-middle attacks on TLS

Answer

Replay attacks on authentication tokens

Answer

Phishing attacks

Question 11

An IoT device manufacturer wants to ensure that firmware updates are authentic and have not been tampered with. The device has limited computational resources. Which cryptographic primitive is most appropriate for verifying the integrity and authenticity of firmware images?

Accepted Answer

Digital signature using ECDSA P-384. Digital signatures provide both integrity and authenticity. RSA is too computationally intensive for constrained devices; ECDSA or Ed25519 are more suitable. The question asks for the primitive, so digital signatures is the correct category.

Answer

SHA-256 hash only

Answer

Symmetric MAC using AES-256-GCM

Answer

HMAC-SHA256 with a device-specific key

Question 12

During a security audit, it was discovered that an application uses RSA with 1024-bit keys for encrypting sensitive data. The organization's security policy mandates a minimum of 128-bit symmetric equivalent security. Which of the following should be recommended as a replacement?

Accepted Answer

RSA with 3072-bit keys. RSA 2048 provides approximately 112-bit security, while RSA 3072 provides 128-bit. AES-256-GCM is symmetric, not asymmetric. ECDSA is for signatures, not encryption. So RSA 3072 is the correct choice.

Answer

AES-256-GCM

Answer

ECDSA P-384

Answer

RSA with 2048-bit keys

Question 13

A security engineer is configuring a web server to use TLS 1.3. Which feature of TLS 1.3 should be disabled to prevent replay attacks in 0-RTT mode?

Accepted Answer

0-RTT. 0-RTT data is vulnerable to replay; disabling 0-RTT eliminates this risk. However, the question asks what should be disabled to prevent replay attacks in 0-RTT mode, so the answer is 0-RTT itself.

Answer

Session resumption

Answer

Forward secrecy

Answer

Cipher suite negotiation

Question 14

A PKI administrator is deploying certificates for code signing. Which certificate type should be used to ensure that the signed code can be verified by clients without requiring a full chain validation?

Accepted Answer

Code signing certificate. A code signing certificate is specifically designed to sign software and scripts, allowing clients to verify the integrity and origin of the code. When a client verifies a signed executable, it checks the signature against the certificate's public key and validates the certificate chain. However, the question's phrasing about 'without requiring a full chain validation' is misleading; in practice, code signing still relies on chain validation unless the certificate is explicitly trusted. The correct answer is C because it is the only certificate type intended for code signing, and the other options serve different purposes.

Answer

EV certificate

Answer

S/MIME certificate

Answer

DV certificate

Question 15

During a security assessment, an engineer discovers that a smartcard used for authentication is vulnerable to side-channel attacks. Which countermeasure would best mitigate power analysis attacks?

Accepted Answer

Adding redundant cryptographic operations to equalize power consumption. Power analysis attacks exploit variations in power consumption; constant-time algorithms and power smoothing hardware help mitigate this.

Answer

Using a shielded enclosure to reduce electromagnetic emissions

Answer

Increasing the key length

Answer

Implementing a hardware random number generator