Question 120
The assessor confirmed this exposure: An SOC has logs of suspicious remote service creation but its coverage board tracks only alert names, making it difficult to find unmapped adversary behavior and missing detections. Which change most directly closes the underlying security gap?
- Use tamper-evident logs and tightly scoped write privileges
- Map detections and gaps to techniques with supporting telemetry
- Update the threat model when data flows or trust boundaries change
- Reconcile source review with runtime verification of discovered flaws
Explanation
Correct Answer
B:Technique-level coverage helps identify missing logs and analytics while avoiding false certainty about adversary identity from a single behavior. It targets the actual failure mode: MITRE ATT&CK organizes observed tactics and techniques across attack stages; mapping behavior supports detection coverage and investigation without requiring attribution to a particular actor.
Incorrect Answers
A:Integrity controls make unauthorized modification harder and expose alterations through protected audit trails or cryptographic verification of record changes; the exposure here is MITRE ATT&CK technique mapping, which calls for another protective mechanism.
C:A design-level review must track new integrations and privileges; otherwise earlier assumptions stop representing the system being protected; this is relevant to a separate threat modeling scenario, rather than the identified exposure; the tested fault instead involves MITRE ATT&CK technique mapping.
D:Knowing the code does not itself demonstrate exploitability in the deployed configuration; validated runtime behavior makes the finding dependable; the tested weakness is MITRE ATT&CK technique mapping, not the white-box assessment configuration addressed here.
Question 121
A security change request summarizes the problem as follows: A protocol designer needs to wrap a randomly generated session key using an RSA recipient key while avoiding unsafe textbook-style public-key encryption. Which remediation is best suited to it?
- Store salted passwords using tuned Argon2id parameters
- Enforce modern minimum TLS versions and remove unsafe fallback
- Use an approved OAEP padding mode and hybrid encryption design
- Use HMAC with secret-key rotation and canonical message formatting
- Inventory vulnerable public-key uses and plan standards-based post-quantum migration
- Guarantee unique nonces per encryption key and rotate affected keys
Explanation
Correct Answer
C:A random symmetric data key handles bulk encryption efficiently while correctly padded RSA protects key transport. It targets the actual failure mode: RSA-OAEP uses randomized asymmetric encryption padding suitable for wrapping short secrets, not for bulk data encryption at high throughput.
Incorrect Answers
A:Unique salts defeat precomputed matches and memory-hard derivation increases the cost of large-scale cracking of leaked verifiers; the proposed improvement would make sense for argon2id password storage but not as the main fix here; the tested fault instead involves RSA-OAEP encryption.
B:Strong negotiation policy keeps a transient handshake failure from authorizing obsolete protocol use; the specific root cause belongs to RSA-OAEP encryption, beyond this control's intended scope.
D:Only holders of the shared secret can produce a valid tag, while consistent serialization prevents verification discrepancies; it would improve HMAC integrity check, not directly correct the reported RSA-OAEP encryption issue.
E:Cryptographic agility and vendor-supported post-quantum algorithms address long-lived confidentiality risks without assuming existing symmetric ciphers fail identically; the measure addresses a different trust boundary from the RSA-OAEP encryption finding.
F:Nonce-generation discipline protects the authentication construction, while key rotation limits exposure after uniqueness guarantees have failed; the required correction concerns RSA-OAEP encryption, so this is not the targeted control.
Question 122
An authorized security review documents this behavior: A process historian that stores past operational readings is accessible from an enterprise user subnet without application-specific read restrictions. Which mechanism best accounts for the finding?
- Exposed UPnP forwarding
- PLC command tampering
- Exposed industrial historian
- Exposed hardware debug port
Explanation
Correct Answer
C:Historians aggregate industrial process data and may reveal operational patterns or expose interfaces bridging enterprise and control environments. The control that addresses this failure path is to segment historian access and enforce application-specific read permissions; controlled paths preserve authorized reporting while reducing broad visibility into industrial telemetry and possible pivot routes.
Incorrect Answers
A:UPnP IGD can automate NAT port mappings; overly permissive control or exposure may open unintended paths from external networks; those prerequisites differ from the exposed industrial historian behavior in the record.
B:Programmable logic controllers act on control instructions that may affect physical processes; insecure command channels can translate cyber access into unsafe operations; this would classify another type of evidence, whereas the actual finding shows exposed industrial historian.
D:Hardware debug interfaces may expose console access, memory, or privileged firmware operations outside the normal network authentication model; those effects are not the exposed industrial historian pattern evidenced by the assessment.
Question 123
Operations asks for a practical correction after the test found: The inventory program scans only IPv4 ranges on a dual-stack campus and misses management interfaces reachable from neighboring IPv6-capable devices. What should the security team recommend?
- Include IPv6 address space and neighbor traffic in authorized inventory scans
- Correlate unusual completed connections across many service ports
- Patch identified software and minimize optional version disclosure
- Reduce authorized probe rates and correlate results with perimeter logs
- Validate ambiguous UDP results with protocol-aware requests
Explanation
Correct Answer
A:A complete host inventory must cover IPv6, while security controls should not disable essential ICMPv6 functions needed for normal operation. The underlying condition is that IPv6 neighbor discovery resolves local-link peers using ICMPv6 rather than ARP; IPv4-only discovery cannot account for dual-stack assets.
Incorrect Answers
B:Service logs and perimeter telemetry can reveal this scan pattern even when the scanner lacks the privileges needed to craft raw packets; that safeguard does not directly close the IPv6 neighbor discovery route highlighted by the test.
C:Version knowledge supports accurate inventory and remediation; changing a port or suppressing a banner alone does not remove vulnerable code; the proposed improvement would make sense for service version probing but not as the main fix here; the tested fault instead involves IPv6 neighbor discovery.
D:Controlled timing improves reproducibility and avoids mistaking defensive drops or transient congestion for a change in service configuration; the specific root cause belongs to IPv6 neighbor discovery, beyond this control's intended scope.
E:Application-specific probes and correlated firewall logs help distinguish a silent UDP listener from network filtering without guessing from silence; that change targets UDP service discovery, while the confirmed weakness involves IPv6 neighbor discovery.
Question 124
Consider this event from a scoped security assessment: A previously unknown public key appears in an account's authorized_keys file and later permits login without the account password. Which explanation fits the observed evidence?
- Security-log tampering
- SSH authorized-key persistence
- Cron-job persistence
- Pass-the-hash authentication
- Offline password hash attack
Explanation
Correct Answer
B:SSH public-key authentication trusts allowed public keys in account configuration; adding an unapproved key can preserve remote access independent of password rotation. For a production safeguard, operators can review authorized keys and centrally manage approved SSH principals; removing unauthorized trust entries and limiting key enrollment close the bypass that persists when only local passwords are changed.
Incorrect Answers
A:Log clearing or alteration attempts to obstruct detection; independent forwarded records can preserve evidence even when a compromised host loses local history; the relevant mechanism in the observed workflow is SSH authorized-key persistence instead.
C:Cron executes scheduled commands under a designated user context, so a malicious job can survive session termination and run unattended; the case demonstrates SSH authorized-key persistence rather than the alternate mechanism.
D:Pass-the-hash reuses suitable password-derived authentication material directly in NTLM exchanges; it is not the same as decrypting a stored password; the observed evidence concerns SSH authorized-key persistence instead.
E:Offline cracking compares computed candidate hashes with stored password verifiers; network account lockouts do not normally constrain the local comparison process; the test record points specifically to SSH authorized-key persistence, not this separate mechanism.
Question 125
A control review considers a verified technical issue: A perimeter appliance exhausts its pending TCP-connection queue from incomplete handshakes while the backend service is healthy when tested from a trusted network. Which mitigation most directly addresses its cause?
- Update NTP software and disable unnecessary monitoring commands
- Normalize cache keys and rate-limit expensive uncached operations
- Enforce header completion timeouts and concurrency limits
- Enable SYN cookies or equivalent connection-state protections
- Use upstream filtering and volumetric DDoS mitigation
Explanation
Correct Answer
D:SYN cookies and tuned backlog handling reduce memory pressure from incomplete handshakes while retaining normal completed TCP connections. This matters for the observed attack path because a SYN flood consumes connection-state resources before handshakes complete; spoofed or unresponsive source addresses can aggravate backlog exhaustion.
Incorrect Answers
A:Patched and restricted control interfaces remove the oversized response path while preserving legitimate network time service; the action is aimed at NTP amplification; it leaves the central TCP SYN flood condition unresolved.
B:Cache configuration and request controls reduce origin amplification from meaningless parameter variations while preserving valid user queries; this is relevant to a separate cache-busting request flood scenario, rather than the identified exposure; the tested fault instead involves TCP SYN flood.
C:Short header deadlines and bounded connection slots release resources from clients that never submit a complete request; the tested weakness is TCP SYN flood, not the slowloris header exhaustion configuration addressed here.
E:Provider-level controls drop unwanted volume before the limited access link becomes saturated, unlike an application-only request throttle; the proposed improvement would make sense for UDP packet flood but not as the main fix here; the tested fault instead involves TCP SYN flood.
Question 126
The approved test uncovered this weakness: A standard Microsoft management binary invokes a remote payload in a way that fits neither its normal automation schedule nor the initiating user's job role. Which control would reduce the relevant exposure without relying on obscurity?
- Use integrity monitoring and execution controls on trusted binaries
- Correlate high-volume failed DNS queries and apply protective DNS
- Maintain tested YARA rules and validate matches against behavior
- Constrain script execution and detect abnormal parent-child process chains
Explanation
Correct Answer
D:Behavioral context catches misuse of approved binaries without incorrectly treating every built-in administration utility as malware. The underlying condition is that living-off-the-land behavior abuses legitimate operating-system tools to perform malicious work, so executable reputation alone may be insufficient.
Incorrect Answers
A:File verification and controlled execution help identify infected hosts and interrupt propagation through modified application files; the specific root cause belongs to living-off-the-land misuse, beyond this control's intended scope.
B:Unusual query distributions and known algorithmic patterns help detect rotating rendezvous attempts before a successful connection; that change targets domain generation algorithm, while the confirmed weakness involves living-off-the-land misuse.
C:Quality rule design and triage reduce false positives and let analysts detect related artifacts even when their full-file hashes differ; it would improve YARA rule matching, not directly correct the reported living-off-the-land misuse issue.
Question 127
A controlled investigation yields this observation: A team incorrectly assumes that a short, outdated digest proves a document is unique because no second message could share its output. How should the team identify the underlying behavior?
- HMAC integrity check
- RSA-OAEP encryption
- Hash collision concept
- Cryptographic key rotation
Explanation
Correct Answer
C:A cryptographic collision occurs when distinct inputs produce the same digest; fixed-size hashes necessarily have possible collisions, with practical resistance varying by algorithm. On affected systems, it is useful to use collision-resistant modern hashes for integrity-sensitive applications; a strong current digest reduces feasible collision attacks; obsolete algorithms such as MD5 should not secure document authenticity claims.
Incorrect Answers
A:HMAC combines a cryptographic hash with a shared secret to authenticate message integrity; it does not encrypt message contents; the observed evidence concerns hash collision concept instead.
B:RSA-OAEP uses randomized asymmetric encryption padding suitable for wrapping short secrets, not for bulk data encryption at high throughput; the test record points specifically to hash collision concept, not this separate mechanism.
D:Key rotation periodically replaces cryptographic key material, reducing exposure windows; encrypted historical data may still depend on older keys; the scenario identifies hash collision concept, which has a different triggering condition.
Question 128
A production hardening ticket was raised after this confirmed observation: A business firewall is required to block new inbound internet sessions while still allowing responses to authorized outbound client sessions without opening every return port. Which action best targets the risk?
- Use approved endpoint telemetry or controlled TLS inspection when justified
- Require compliant device posture and quarantine unmanaged endpoints
- Tune baselines using service context and investigate deviations
- Use default-deny inbound policies with state tracking and explicit exceptions
Explanation
Correct Answer
D:Session-aware filtering allows expected responses without opening general inbound reachability to unrelated external clients. The safeguard responds to the underlying issue: stateful inspection tracks connection context, unlike a stateless rule that examines each packet primarily by addresses, ports, and flags.
Incorrect Answers
A:Instrumenting the endpoint or authorized termination point recovers necessary context without assuming a passive sensor can decrypt arbitrary TLS; that safeguard does not directly close the stateful firewall inspection route highlighted by the test.
B:Access gating reduces untrusted device reachability before normal segmentation and application controls are applied; the proposed improvement would make sense for NAC posture enforcement but not as the main fix here; the tested fault instead involves stateful firewall inspection.
C:Context-aware thresholds improve signal quality while preserving visibility into behavior that does not match a known static signature; the specific root cause belongs to stateful firewall inspection, beyond this control's intended scope.
Question 129
A remediation meeting focuses on the following finding: An external review identifies an old web daemon family in a response header but cannot establish whether the installed patch level is current or the banner was deliberately changed. Which proposed action best addresses its root cause?
- Include IPv6 address space and neighbor traffic in authorized inventory scans
- Review supported TLS versions and certificate validation on the real service
- Monitor SYN probing patterns and apply network exposure controls
- Patch identified software and minimize optional version disclosure
Explanation
Correct Answer
D:Version knowledge supports accurate inventory and remediation; changing a port or suppressing a banner alone does not remove vulnerable code. The technical basis for the recommendation is that service detection sends protocol-aware probes and interprets server responses; the port number alone does not prove which application is listening.
Incorrect Answers
A:A complete host inventory must cover IPv6, while security controls should not disable essential ICMPv6 functions needed for normal operation; the measure addresses a different trust boundary from the service version probing finding.
B:Hardening protocol negotiation and certificate chains prevents downgrade and impersonation weaknesses that a simple open-port scan cannot detect; the required correction concerns service version probing, so this is not the targeted control.
C:Connection attempts to many ports can indicate reconnaissance; reducing reachable listeners is stronger protection than hiding TCP banners alone; its security benefit applies principally to TCP SYN scan, not the defect described; the tested fault instead involves service version probing.
Question 130
A control review considers a verified technical issue: The security team wants each corporate laptop to authenticate with its own managed certificate and reject enterprise Wi-Fi authentication servers whose identity cannot be verified. Which mitigation most directly addresses its cause?
- Use a strong random passphrase or move to enterprise authentication
- Manage certificate enrollment and enforce trusted RADIUS server identity
- Avoid entering corporate passwords into unverified Wi-Fi portal pages
- Retire TKIP-only clients and require AES-CCMP or better
Explanation
Correct Answer
B:Strong certificate lifecycle and server validation reduce shared-secret exposure and prevent clients from sending credentials to spoofed authentication servers. This matters for the observed attack path because EAP-TLS in an 802.1X enterprise deployment provides certificate-based mutual authentication when both supplicant and server validate credentials correctly.
Incorrect Answers
A:High-entropy secrets resist offline guesses, while per-user enterprise credentials remove the single shared passphrase from the whole fleet; this is relevant to a separate WPA2-Personal weak passphrase scenario, rather than the identified exposure; the tested fault instead involves 802.1X EAP-TLS identity.
C:Trusted onboarding methods and validated sign-in domains keep general network-access prompts from becoming identity-theft channels; that safeguard does not directly close the 802.1X EAP-TLS identity route highlighted by the test.
D:Modern cipher suites remove legacy cryptographic exposure while avoiding insecure fallback choices driven by obsolete equipment; the proposed improvement would make sense for TKIP legacy cipher but not as the main fix here; the tested fault instead involves 802.1X EAP-TLS identity.