CAS-004 Security Engineering Practice Test 11 — 15 Questions

Question 1

A financial services company is deploying a new internal web application that must meet PCI DSS requirements for encrypting cardholder data in transit. The security engineer must configure TLS to ensure that only ephemeral key exchanges are used and that compromised long-term keys cannot decrypt past sessions. Which of the following should the engineer implement?

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

Accepted Answer

Enable TLS 1.3 with cipher suites that use ephemeral Diffie-Hellman (DHE or ECDHE) key exchange.. TLS 1.3 enforces forward secrecy by requiring ephemeral key exchange, so even if the server's long-term private key is compromised, past session keys remain secure. The other options either use static key exchanges that lack forward secrecy or include deprecated algorithms like SHA-1. For PCI DSS compliance, ephemeral Diffie-Hellman with TLS 1.3 is the most robust choice.

Answer

Deploy TLS 1.2 with AES-256-GCM and ensure the server certificate uses SHA-1 for signing.

Answer

Implement TLS 1.2 with static Diffie-Hellman parameters and a 4096-bit RSA certificate.

Answer

Configure the server to use TLS 1.2 with RSA key exchange and 2048-bit RSA certificates.

Question 2

A security engineer is configuring a Linux bastion host that must use only the strongest key-exchange method available in OpenSSH, avoiding any Diffie-Hellman group that relies on finite-field modular exponentiation. Which sshd_config directive setting should the engineer apply?

Accepted Answer

KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org. Restricting KexAlgorithms to the X25519-based curve25519-sha256 variants forces the server and client to use elliptic-curve Diffie-Hellman, eliminating all finite-field modular-exponentiation groups. The other directives govern ciphers or host-key signatures and leave the default key-exchange list, which still permits classic DH groups, intact. Only the KexAlgorithms restriction directly enforces the stated cryptographic constraint.

Answer

KexAlgorithms diffie-hellman-group14-sha256

Answer

HostKeyAlgorithms ssh-ed25519

Answer

Ciphers chacha20-poly1305@openssh.com

Question 3

A security engineer must select a cryptographic hash function for a new code-signing service that will protect firmware for at least 15 years. The service must resist length-extension attacks and provide collision resistance against well-funded adversaries. The organization's policy requires FIPS 140-3 validated modules only. Which hash function BEST meets these requirements?

Accepted Answer

SHA3-256. SHA3-256 is the only listed option that combines FIPS approval, strong collision resistance, and intrinsic resistance to length-extension attacks. The sponge construction avoids the Merkle-Damgard weakness that affects SHA-256, SHA-1, and MD5. Given the 15-year firmware-signing horizon and the explicit anti-length-extension requirement, SHA3-256 is the appropriate engineering choice.

Answer

SHA-256

Answer

MD5

Answer

SHA-1

Question 4

A security engineer is hardening a containerized workload platform against attacks that escape a container and reach the host kernel. The team wants to reduce the kernel attack surface available to each container without breaking application functionality. Which TWO measures BEST accomplish this? (Choose two.)

Accepted Answer

Apply a seccomp profile that allows only the system calls the application actually uses and denies the rest by default.. Default-deny seccomp profiles and least-privilege capability sets both operate at the kernel boundary and remove entire classes of privileged operations from containerized processes. Together they ensure that even a fully exploited application lacks the system calls and capabilities needed to reach host kernel interfaces, which is precisely the attack surface reduction the team requires.

Answer

Run the container runtime with the Docker socket mounted into every container so the platform can manage sibling containers.

Answer

Disable mandatory access control frameworks such as AppArmor or SELinux so the application is not blocked by policy denials.

Answer

Set the container to run as the root user inside its namespace to avoid file permission problems during deployment.

Question 5

A security administrator is configuring a network intrusion detection system (NIDS) to monitor traffic for known attack patterns. The administrator wants to ensure that the NIDS can detect a specific SQL injection attempt that uses a particular string. Which Snort rule action and option combination will BEST accomplish this?

Accepted Answer

alert tcp any any -> any 80 (msg:"SQL Injection"; content:"1=1"; sid:100001;). The goal is to detect a SQL injection attempt containing a specific string. Snort rules with the alert action and a content match on TCP port 80 are appropriate for unencrypted HTTP traffic. Using drop would block traffic, which is not required. UDP or port 443 would not match typical SQL injection traffic. Thus, the rule with alert, TCP, port 80, and content match is correct.

Answer

alert udp any any -> any 80 (msg:"SQL Injection"; content:"1=1"; sid:100001;)

Answer

drop tcp any any -> any 80 (msg:"SQL Injection"; content:"1=1"; sid:100001;)

Answer

alert tcp any any -> any 443 (msg:"SQL Injection"; content:"1=1"; sid:100001;)

Question 6

A security engineer is implementing a secure boot process for a Linux server. The requirement is to ensure that only signed and trusted kernel modules can be loaded, preventing rootkits from persisting. Which mechanism should the engineer enable?

Accepted Answer

Kernel module signing enforcement (module.sig_enforce=1).. Kernel module signing enforcement is the specific mechanism that requires all kernel modules to be signed with a trusted key before they can be loaded. When enabled via the module.sig_enforce=1 kernel parameter, the kernel rejects any module without a valid signature. This prevents rootkits that use kernel modules from persisting, as they cannot be loaded. UEFI Secure Boot, SELinux, and IMA provide related but distinct protections that do not directly enforce module signing at load time.

Answer

Integrity Measurement Architecture (IMA) with appraisal.

Answer

UEFI Secure Boot with a custom key enrollment.

Answer

Linux Security Modules (LSM) with SELinux in enforcing mode.

Question 7

A security administrator is reviewing the configuration of a wireless network that uses WPA3-Enterprise. The administrator wants to ensure that the authentication mechanism provides mutual authentication and supports centralized policy enforcement. Which of the following should be used?

Accepted Answer

802.1X with EAP-TLS. EAP-TLS is the strongest EAP method for WPA3-Enterprise because it uses certificates for both client and server, enabling mutual authentication and centralized policy enforcement through RADIUS. The other methods either do not provide mutual certificate-based authentication, are designed for personal networks, or do not meet WPA3-Enterprise standards.

Answer

WPA2-Enterprise with PEAP-MSCHAPv2

Answer

WPA3-Personal with SAE

Answer

802.1X with EAP-TTLS/PAP

Question 8

A security engineer is hardening a Kubernetes cluster that runs multi-tenant workloads. The requirement is to prevent a compromised pod from reading another tenant's secrets and from making unauthorized network connections to other namespaces. Which of the following combinations BEST addresses both concerns?

Accepted Answer

Apply network policies that deny ingress and egress by default and mount secrets only into pods that explicitly require them with least-privilege service accounts. Default-deny network policies enforce network segmentation between namespaces, and least-privilege service accounts with scoped secret mounts enforce secret isolation at the API level. The other options harden adjacent layers such as control-plane access, admission, or transport encryption without preventing the two specific cross-tenant actions described.

Answer

Enable role-based access control (RBAC) for the API server and require TLS client certificates for all kubelet connections

Answer

Deploy a service mesh with mutual TLS between all pods and rotate the cluster's certificate authority on a fixed schedule

Answer

Use pod security admission to enforce the restricted profile and enable audit logging on the API server for all secret access

Question 9

A security architect is designing a system that must ensure the confidentiality and integrity of data at rest on a database server. The architect plans to use full-disk encryption (FDE) with a TPM 2.0 module. Which of the following BEST describes a limitation of this approach that the architect must address?

Accepted Answer

FDE with TPM does not protect data if the operating system is running and an attacker gains remote access.. Full-disk encryption with TPM protects data at rest when the system is off or locked. Once the OS is running, the volume is decrypted and accessible to any process with sufficient privileges, including remote attackers. This runtime exposure is the key limitation. Other options misstate TPM capabilities or conflate optional features with fundamental constraints.

Answer

TPM 2.0 modules are vulnerable to cold boot attacks that can extract the encryption key from RAM.

Answer

TPM 2.0 requires a PIN to be entered at every boot, which is impractical for servers.

Answer

FDE with TPM cannot be used with self-encrypting drives (SEDs) or hardware encryption.

Question 10

A security engineer is designing a hybrid encryption solution for a messaging application. The requirement is that each message must be encrypted with a unique symmetric key, and that symmetric key must be delivered to the recipient without exposing it to the server. The solution must also support sender authentication. Which combination of cryptographic mechanisms BEST satisfies these requirements?

Accepted Answer

Encrypt the message with AES-256-GCM using a randomly generated key, encrypt that key with the recipient's RSA public key, and sign the ciphertext with the sender's RSA private key.. Hybrid encryption combines asymmetric and symmetric cryptography to meet confidentiality, integrity, and authentication goals. A random AES-GCM key per message ensures unique symmetric keys, RSA key wrapping delivers that key confidentially to the recipient, and a sender signature binds the message to the sender's identity. The other options either leak key material, use impractical direct asymmetric encryption, or omit sender authentication.

Answer

Use Diffie-Hellman key exchange to establish a shared secret, encrypt the message with that secret using AES-256-GCM, and rely on the shared secret itself to authenticate the sender.

Answer

Encrypt the message with AES-256-CBC using a key derived from the sender's password, and include the password hash in the message header for verification.

Answer

Encrypt the message directly with the recipient's RSA public key, and have the recipient verify authenticity by comparing a SHA-256 hash sent alongside the ciphertext.

Question 11

A security analyst is reviewing a packet capture and observes that a client and server negotiate a session key using ephemeral Diffie-Hellman, after which all application data is encrypted with a symmetric cipher. The analyst wants to document which security property the ephemeral key exchange provides that a static RSA key transport would not. Which property is that?

Accepted Answer

Forward secrecy, because compromise of the long-term private key does not reveal past session keys.. Ephemeral Diffie-Hellman creates a unique shared secret per session and erases the private ephemeral values, so a later compromise of the server's long-term key cannot decrypt previously captured traffic. Static RSA key transport ties the premaster secret to the long-term key, so that compromise exposes all recorded sessions. The distinguishing property is forward secrecy.

Answer

Perfect confidentiality of the server certificate, because the certificate is encrypted during the handshake.

Answer

Non-repudiation, because the ephemeral key pair proves the server's identity to the client.

Answer

Data integrity, because Diffie-Hellman produces a message authentication code over each record.

Question 12

A security operations center (SOC) is implementing a new SIEM and wants to improve detection of credential-based attacks. The team plans to ingest Windows Security event logs and create correlation rules. Which TWO event IDs should the SOC prioritize to detect a brute-force attack against local accounts? (Choose two.)

Accepted Answer

4625 (An account failed to log on). Brute-force attacks against local accounts are characterized by repeated failed logon attempts, which generate Event ID 4625. When the number of failures exceeds the account lockout threshold, Event ID 4740 is logged. Correlating these two events allows the SOC to detect both the ongoing attack and its impact. Other events like successful logons or privilege assignments are not direct indicators of the attack itself, and log clearing is a post-compromise action.

Answer

4624 (An account was successfully logged on)

Answer

4672 (Special privileges assigned to new logon)

Answer

1102 (The audit log was cleared)

Question 13

A security architect must protect a hardware security module's firmware against an attacker who has physical access and can measure power consumption and electromagnetic emissions during signature operations. The architect wants a countermeasure that makes the secret key statistically uncorrelated with the observable side-channel leakage. Which approach BEST meets this goal?

Accepted Answer

Implement constant-time modular exponentiation with blinding of the base and exponent. Base and exponent blinding combined with constant-time arithmetic randomize the intermediate values on which the leakage depends, so power and EM traces no longer correlate with the secret exponent. Secure boot, at-rest encryption, and rate limiting all leave the runtime arithmetic unchanged and therefore do not stop differential power analysis by an attacker with physical measurement access.

Answer

Rate-limit signature operations to ten per second and log each attempt

Answer

Enable secure boot with a signed firmware image verified by an on-die ROM

Answer

Store the private key in encrypted form using an AES key derived from a PIN

Question 14

A security architect is designing a microservices-based application deployed on a Kubernetes cluster. The architect must ensure that inter-service communication is encrypted, mutually authenticated, and that services can be authorized based on their identity. Which of the following should the architect implement to meet these requirements?

Accepted Answer

Deploy a service mesh with mutual TLS (mTLS) and identity-based authorization policies.. A service mesh with mTLS provides transparent encryption and mutual authentication for all service-to-service communication, using verifiable identities. Its authorization policies can enforce access based on those identities, which is essential for zero-trust microservices. The other options either lack encryption, mutual authentication, or are limited to external traffic, failing to secure east-west communication.

Answer

Use Kubernetes Secrets to store TLS certificates and manually configure each service to use them.

Answer

Implement an API gateway that terminates TLS and performs authentication for all inbound traffic.

Answer

Configure Kubernetes Network Policies to allow only specific pod-to-pod traffic.

Question 15

A security architect is designing a data-at-rest protection scheme for a multi-tenant SaaS platform. The requirement is that each tenant's data be encrypted with a unique key, and that compromise of one tenant's key never exposes another tenant's data. The platform must support cryptographic erasure of a single tenant without re-encrypting the entire database. Which design BEST satisfies these requirements?

Accepted Answer

Use a per-tenant data encryption key wrapped by a key encryption key, and destroy the wrapped data key to erase that tenant.. Envelope encryption with a unique wrapped data key per tenant provides both cryptographic isolation and efficient cryptographic erasure. Destroying a single wrapped data key makes that tenant's ciphertext unrecoverable while leaving the key encryption key and all other tenants untouched. This avoids full-database re-encryption and ensures that one key compromise cannot cascade across tenants.

Answer

Encrypt all tenant data with a single database master key and rely on row-level access controls to isolate tenants.

Answer

Encrypt each tenant's data with a key derived from the tenant identifier using PBKDF2, and rotate the derivation salt to erase the tenant.

Answer

Store each tenant's data in a separate database encrypted with a shared HSM-backed key, and delete rows to erase a tenant.