CAS-004 Security Engineering Practice Test 4 — 15 Questions

Question 1

A security architect is designing a key management system for a multi-tenant cloud environment. The requirement is to ensure that encryption keys are never stored in plaintext and that a compromise of one tenant's key does not affect others. Which approach BEST meets these requirements?

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

Accepted Answer

Use a hardware security module (HSM) to generate and store a master key, and derive per-tenant data encryption keys using HKDF with the tenant ID as context.. The best approach uses an HSM to protect a master key and derives per-tenant keys using a key derivation function with tenant-specific context. This ensures no plaintext keys are stored and provides cryptographic isolation between tenants. Other options either share keys, store encrypted keys (which is less clean), or require separate HSMs (impractical at scale).

Answer

Encrypt each tenant's data with a shared AES-256 key, and store that key in a secrets manager with access controls based on tenant role.

Answer

Use a separate HSM per tenant to generate and store that tenant's keys, and enforce strict physical access controls.

Answer

Generate a random data encryption key per tenant, encrypt it with a master key stored in an HSM, and store the encrypted key alongside the tenant's data.

Question 2

A security engineer is configuring a Windows Server 2022 jump host that must accept SSH connections only from a managed administrative subnet, permit only public-key authentication, and prevent interactive shell access for automated file-transfer accounts. The engineer plans to enforce these requirements through the native OpenSSH server configuration file. Which TWO sshd_config directives should the engineer set to meet the access-control and authentication requirements? (Choose two.)

Accepted Answer

PasswordAuthentication no. The two directives that together satisfy the scenario are AllowUsers with a user@subnet pattern and PasswordAuthentication no. The AllowUsers pattern limits the account to the managed administrative subnet, while disabling password authentication forces public-key authentication for all logins. Neither directive alone covers both the source restriction and the authentication method, and the other options address root login, PAM integration, or host-based trust, none of which meet the access-control and authentication requirements.

Answer

PermitRootLogin prohibit-password

Answer

HostbasedAuthentication yes

Answer

UsePAM yes

Question 3

A security engineer is configuring a Linux web server that must only accept TLS 1.3 connections and must allow the server to select the cipher suite based on its own preference. The engineer wants to disable all TLS 1.2 and earlier protocols and ensure that the server's cipher preference is honored. Which of the following OpenSSL configuration directives should the engineer set in the server's configuration file?

Accepted Answer

MinProtocol = TLSv1.3 and Options = ServerPreference. OpenSSL configuration files use MinProtocol to set the minimum TLS version and Options = ServerPreference to enforce server-side cipher ordering. Setting MinProtocol = TLSv1.3 disables TLS 1.2 and earlier, while ServerPreference ensures the server's cipher list is prioritized over the client's. This combination satisfies both requirements without relying on web server-specific directives.

Answer

SSLProtocol -all +TLSv1.3 and SSLHonorCipherOrder on

Answer

SSLProtocol TLSv1.3 and SSLHonorCipherOrder on

Answer

CipherString = DEFAULT and Protocol = TLSv1.3

Question 4

A security engineer is designing network segmentation for a container platform. The requirement is that a compromised pod must not be able to reach the cloud provider's instance metadata service to steal node credentials, while pods must still reach legitimate internal APIs. Which control BEST achieves this?

Accepted Answer

Enforce IMDSv2 with a hop limit of one on the nodes so that pods cannot obtain metadata credentials.. Enforcing IMDSv2 with a hop limit of one is the provider-native control that specifically prevents pods from reaching the instance metadata service, because the session-token PUT and the extra hop requirement stop pod-originated requests. Broader egress policy, pod hardening, and mesh encryption address different layers and do not directly close the metadata credential path.

Answer

Use a service mesh to encrypt all pod-to-pod traffic with mutual TLS and enforce authorization policies.

Answer

Run all pods with a read-only root filesystem and drop the CAP_NET_RAW capability.

Answer

Apply a network policy that denies all egress from the pod namespace except to explicitly allowed internal API destinations.

Question 5

A security engineer is configuring a Linux web server that must use TLS 1.3 exclusively. The server hosts multiple virtual hosts with different certificates, and the engineer wants to ensure that the server selects the correct certificate based on the SNI value sent by the client. Which OpenSSL configuration directive should the engineer use to enable SNI-based certificate selection?

Accepted Answer

SSL_CTX_set_tlsext_servername_callback. The SSL_CTX_set_tlsext_servername_callback function is specifically designed to handle the TLS SNI extension. When a client initiates a handshake, this callback is triggered with the hostname, allowing the server to switch to the appropriate SSL_CTX containing the correct certificate. This enables multiple virtual hosts with different certificates on a single IP address, which is essential for modern TLS 1.3 deployments.

Answer

SSL_CTX_set_cert_cb

Answer

SSL_CTX_set_session_ticket_cb

Answer

SSL_CTX_set_alpn_select_cb

Question 6

A security architect is designing a system that requires secure deletion of sensitive data stored on magnetic hard disk drives (HDDs). The data must be rendered unrecoverable even if an attacker gains physical possession of the drive and uses advanced forensic techniques. The organization wants to use a method that is approved by NIST SP 800-88 Rev. 1 for purging media. Which of the following methods should the architect select?

Accepted Answer

Using the ATA Secure Erase command to purge the drive. NIST SP 800-88 Rev. 1 lists ATA Secure Erase as an approved purge method for ATA hard drives that support it. It overwrites all sectors, including reallocated ones, ensuring data is unrecoverable. Degaussing is also approved but requires proper field strength; overwriting once is only a clear; and cryptographic erasure requires pre-existing encryption. ATA Secure Erase is the most straightforward and reliable choice for a compatible drive.

Answer

Overwriting the entire drive with a single pass of random data

Answer

Degaussing the drive with a magnetic field strength of at least 5,000 gauss

Answer

Encrypting the drive with full disk encryption (FDE) and then deleting the encryption key

Question 7

A security administrator is hardening a Linux web server that terminates TLS for an internal API. The administrator wants to ensure that the server negotiates only cipher suites offering forward secrecy and authenticated encryption, and that clients cannot downgrade to older protocol versions. Which configuration change BEST accomplishes this?

Accepted Answer

Set the OpenSSL cipher string to ECDHE+AESGCM:ECDHE+CHACHA20 and set MinProtocol to TLSv1.2 with TLS 1.3 ciphersuites restricted to TLS_AES_256_GCM_SHA384. The configuration that best meets the goal restricts key exchange to ephemeral ECDHE for forward secrecy, restricts bulk encryption to AES-GCM or ChaCha20-Poly1305 for authenticated encryption, and raises the minimum protocol to TLS 1.2 while constraining TLS 1.3 ciphersuites. The other options either mix incompatible suite names with TLS 1.3, leave CBC and static RSA available, or permit obsolete protocol versions that enable downgrade attacks.

Answer

Set the OpenSSL cipher string to ECDHE-RSA-AES256-GCM-SHA384 and set MinProtocol to TLSv1.3

Answer

Set the OpenSSL cipher string to ECDHE:!aNULL:!eNULL and set MinProtocol to TLSv1.2

Answer

Set the OpenSSL cipher string to HIGH:!MD5 and set MinProtocol to TLSv1.0

Question 8

A security engineer is implementing a solution to detect unauthorized changes to critical system files on a Linux server. The solution must alert the security team in near real-time when a file's content or metadata changes. Which of the following should the engineer deploy?

Accepted Answer

A file integrity monitoring (FIM) tool such as AIDE or Tripwire.. File integrity monitoring tools like AIDE and Tripwire are purpose-built to detect unauthorized changes to files by comparing hashes against a baseline. They can alert on content or metadata changes. HIDS, SIEM, and NIDS may offer related capabilities but are not dedicated to file integrity and require additional components or configurations to achieve the same goal.

Answer

A host-based intrusion detection system (HIDS) such as OSSEC.

Answer

A security information and event management (SIEM) system.

Answer

A network-based intrusion detection system (NIDS) such as Snort.

Question 9

A security engineer is hardening a Windows Server 2022 environment. The engineer needs to configure AppLocker to control which applications can run. Which two rule types can be used to define AppLocker policies? (Choose two.)

Accepted Answer

Path rules. AppLocker supports three rule types: publisher, path, and hash. The question asks for two, and the two most commonly used for general application control are publisher and path rules. Publisher rules use digital signatures, while path rules use file locations. Registry and service rules are not AppLocker rule types, and certificate rules are not a separate category.

Answer

Registry rules

Answer

Service rules

Answer

Hash rules

Question 10

A security architect is evaluating a hardware security module for a payment application that must protect PIN verification keys. The vendor claims the module meets FIPS 140-3 Level 4. Which of the following characteristics should the architect verify to confirm the module provides the physical security expected at that level?

Accepted Answer

The module detects and responds to environmental attacks such as voltage and temperature tampering, and zeroizes keys.. Level 4 is the only FIPS 140-3 level that mandates detection of and response to physical penetration plus environmental attacks, typically voltage and temperature extremes, with automatic zeroization of critical security parameters. Confirming those capabilities is what substantiates the vendor's Level 4 physical security claim for PIN key protection.

Answer

The module performs self-tests at power-on and on demand to confirm correct cryptographic operation.

Answer

The module enforces identity-based authentication and role-based access control for all operators.

Answer

The module uses only approved algorithms and has been validated through the Cryptographic Algorithm Validation Program.

Question 11

A security engineer is configuring a VPN concentrator to support remote workers. The organization requires that the VPN use a protocol that provides confidentiality and integrity for the entire IP packet, including the original IP header, and that it can traverse NAT devices. Which TWO protocols meet these requirements? (Choose two.)

Accepted Answer

IPsec in tunnel mode with NAT-T. IPsec in tunnel mode with NAT-T and WireGuard both encapsulate the entire original IP packet, providing confidentiality and integrity for the packet including its header, and both are designed to traverse NAT. IPsec tunnel mode wraps the whole packet, and NAT-T adds UDP encapsulation. WireGuard uses UDP and encapsulates IP packets. The other options either do not protect the IP header or lack confidentiality.

Answer

TLS in transport mode with DTLS

Answer

IPsec in transport mode with AH

Answer

L2TP over IPsec

Question 12

A security analyst is investigating a potential compromise of a server that uses a TPM 2.0 for disk encryption. The analyst suspects that an attacker with physical access may have performed a cold boot attack to extract encryption keys from memory. Which TPM 2.0 feature, when properly configured, BEST mitigates this attack?

Accepted Answer

Memory encryption with AMD SEV or Intel TME. Cold boot attacks target data in RAM, including encryption keys that have been unsealed from the TPM. Memory encryption technologies like AMD SEV or Intel TME encrypt RAM contents, so even if an attacker freezes and reads memory, the data remains encrypted. This is the most effective TPM-related mitigation when properly configured alongside secure boot and other protections.

Answer

Measured boot with PCRs

Answer

TPM 2.0 dictionary attack protection

Answer

Sealed storage bound to PCR values

Question 13

A security engineer is hardening a web application that handles payment data. The engineer needs to protect against cross-site request forgery (CSRF) while keeping the application stateless and compatible with a REST API consumed by a browser. Which control is MOST appropriate?

Accepted Answer

Require a synchronizer token that is bound to the user's session and validated on every state-changing request.. The synchronizer token pattern is the canonical CSRF defense because the server issues an unpredictable value bound to the authenticated session and verifies it on every state-changing request. A cross-site attacker cannot read or guess that token, so forged requests are rejected even though the browser attaches the session cookie automatically.

Answer

Set the session cookie with the HttpOnly attribute.

Answer

Validate the Origin and Referer headers and reject requests where they do not match the application's domain.

Answer

Rely on the SameSite=Strict attribute on the session cookie as the sole defense.

Question 14

A security administrator is configuring a Linux server to enforce password complexity. The administrator wants to ensure that passwords are at least 12 characters long and include a mix of uppercase, lowercase, digits, and special characters. The administrator also wants to prevent users from reusing their last 5 passwords. Which of the following files should the administrator edit to enforce these requirements using PAM?

Accepted Answer

/etc/pam.d/common-password. On Debian-based Linux systems, PAM password policies are configured in /etc/pam.d/common-password, where the pam_pwquality module enforces complexity and history. The pwquality.conf file provides defaults but must be referenced by PAM. login.defs handles aging, not complexity. system-auth is for Red Hat, but the question likely expects the Debian file.

Answer

/etc/login.defs

Answer

/etc/pam.d/system-auth

Answer

/etc/security/pwquality.conf

Question 15

A security architect is designing a key management system for a multi-tenant cloud environment. The requirement is to ensure that encryption keys are never stored in plaintext and that a compromise of one tenant's key does not affect others. Which approach BEST meets these requirements?

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

Accepted Answer

The KDF must be a one-way function such that deriving the master key from any derived key is computationally infeasible.. The most critical property of a KDF in this context is that it is a one-way function, making it infeasible to derive the master key from any derived key. This ensures that compromising one derived key does not compromise the master key or other derived keys. While salt and computational expense add security, they do not provide this fundamental protection. Determinism is necessary but not sufficient.

Answer

The KDF must use a salt to prevent rainbow table attacks on the master key.

Answer

The KDF must be computationally expensive to slow down brute-force attacks.

Answer

The KDF must be deterministic, producing the same output for the same input and salt.