ECCouncil 312-50v13 - Certified Ethical Hacker Exam (CEH v13 AI)

The correct answer is B, Residual risk. In CEH risk-management terminology, residual risk is the amount of risk that remains after security controls, safeguards, countermeasures, or mitigation strategies have been applied. A penetration test identifies vulnerabilities, threats, and weaknesses that may expose an organization to risk. After the tester recommends controls such as patching, access control improvements, network segmentation, monitoring, hardening, or user awareness training, those controls reduce the likelihood or impact of exploitation. However, security controls rarely remove all risk completely. The remaining exposure is known as residual risk, and management must decide whether to accept, transfer, avoid, or further mitigate it. Inherent risk is the original level of risk before any controls are applied. Gap analysis is a comparison between the current security state and the desired or required state. Total risk usually refers to the overall risk before accounting for implemented safeguards. Therefore, the best term for risk remaining after controls is residual risk.

According to the Certified Ethical Hacker (CEH) System Hacking and Session Hijacking module, sidejacking is a form of session hijacking where an attacker passively intercepts network traffic to capture unencrypted session cookies. These cookies are then reused to impersonate the authenticated user without needing credentials.

CEH documentation explains that sidejacking commonly occurs on unencrypted HTTP connections, public Wi-Fi networks, or improperly secured internal networks. Once the session cookie is stolen, the attacker can replay it to gain access to the victim’s active session.

Option B correctly describes this mechanism and directly matches CEH’s definition of sidejacking.

Option A refers to perimeter exploitation, not session hijacking.

Option C describes social engineering, which is unrelated to sidejacking.

Option D is an example of cross-site scripting (XSS), not sidejacking.

CEH emphasizes HTTPS enforcement and secure cookie attributes as key countermeasures.

The correct answer is C. Insecure Data Storage because the vulnerability described is the storage of sensitive information locally on the mobile device in a manner that is not encrypted and is accessible by simply browsing the file system. In mobile application security, this is a classic risk category: when an app stores confidential data (case notes, client records, tokens, documents, cached responses, databases, logs, or exported files) in clear text or in insecure locations, an attacker who gains device access—or uses backup extraction, file explorers, rooted/jailbroken access, or malware with storage permissions—may retrieve that data without needing to authenticate to the application.

The scenario makes the weakness unmistakable: Daniel can use a “standard explorer tool” to open sensitive records “without any authentication.” This indicates the app is failing to apply appropriate protections such as encryption at rest, secure key handling, proper file permissions, and secure storage mechanisms. In secure mobile design, sensitive records should be encrypted using platform-supported protections (e.g., using OS keystores/keychains for keys, encrypting databases/files, and minimizing local retention). Additionally, apps should avoid storing highly sensitive regulated data unless essential, and should implement secure session controls and data lifecycle management (cache control, expiration, remote wipe support in enterprise settings).

Why the other options are not the best fit: Insecure communication concerns data exposure while transmitted over networks (e.g., lack of TLS, weak TLS, MITM susceptibility), whereas the issue here is purely local storage. Improper credential usage relates to mishandling passwords, tokens, or authentication secrets (hard-coded credentials, weak storage of credentials), but the prompt focuses on stored records themselves. Inadequate privacy controls is broader and typically involves over-collection, improper disclosure, or weak user privacy settings, not direct clear-text storage exposure.

Therefore, the most clearly present OWASP Top 10 Mobile Risk is Insecure Data Storage.

The CEH v13 content explains that stealth scanning involves modifying scan timing parameters to reduce packet frequency, randomize intervals, and avoid recognizable patterns typically flagged by intrusion detection systems. Slow, randomized timing—often achieved with Nmap’s T0 or T1 timing templates—prevents bursts of traffic and allows scans to blend into normal network noise. IDS/IPS systems tuned for high-volume events may fail to detect such gradual reconnaissance. Fast SYN scans generate distinctive patterns easily identified by security monitoring tools. UDP scans, especially across all ports, produce high traffic volume and are extremely noisy. Xmas scans, although sometimes used for stealth against stateless filters, are still signature-detectable and inappropriate when stealth over time is required. Therefore, applying slow, randomized timing options aligns with CEH-approved reconnaissance techniques for evading detection while enumerating open ports.

CEH v13 identifies kernel-level rootkits as among the most dangerous malware types. Because they operate at the lowest OS level, they can hide processes, files, and system calls.

CEH v13 states that the only guaranteed remediation is a complete system wipe and clean OS reinstallation from a trusted source. Attempting removal risks incomplete eradication.

Powering down alone does not remove the rootkit. Honeypots are for detection, not remediation. Tailored removal tools may fail at kernel depth.

Thus, Option C is correct.

The vulnerability described is characteristic of XML External Entity (XXE) Injection. In CEH web application security coverage, XXE occurs when an application parses XML input without properly disabling external entity resolution. If the XML parser is configured insecurely, an attacker can define a malicious external entity that references local files or internal system resources. When the parser processes the XML document, it resolves the external entity and may return the contents of sensitive files in the server’s response.

The scenario clearly states that the issue arises from “handling of external references in document parsing” and results in exposure of internal file paths and database connection strings. This aligns directly with XXE behavior, where attackers leverage external entity declarations to retrieve local files such as configuration files, environment settings, or system credentials. In some cases, XXE can also enable server-side request forgery by forcing the server to make internal network requests.

The other options do not match the described behavior. Identification and authentication failures relate to improper access controls, not document parsing. HTTP response splitting involves manipulating headers to inject malicious responses. Security logging and monitoring failures refer to detection gaps, not data exposure through parsing. CEH-recommended mitigation strategies include disabling DTD processing, turning off external entity resolution in XML parsers, validating input formats, implementing least privilege on file access, and using secure parsing libraries that prevent XXE exploitation.

According to CEH v13, black box testing refers to a testing approach where the ethical hacker has no prior knowledge of the internal structure, source code, or configuration of the system.

The attacker simulates a real-world external attacker, relying solely on discovery and exploitation techniques.

White box testing = full knowledge

Gray box testing = partial knowledge

The correct answer is D. Twofish because the question explicitly describes a symmetric cipher that: (1) works on 128-bit blocks, (2) supports keys up to 256 bits, and (3) was a finalist in the AES selection process intended to replace DES. Twofish matches all of these characteristics. It is a symmetric block cipher designed by Bruce Schneier and colleagues, and it was one of the five AES finalists (along with Rijndael, Serpent, RC6, and MARS). Twofish uses a 128-bit block size and allows key sizes of 128, 192, or 256 bits, aligning precisely with the “up to 256-bit keys” clue.

Why the other choices do not fit: RC4 is a stream cipher, not a 128-bit block cipher, and it is not an AES finalist. AES itself (Rijndael) is the algorithm that ultimately won the AES competition; the prompt says the algorithm was a finalist, not necessarily the winner, and the description is intended to distinguish a finalist option from AES itself. Blowfish supports variable key lengths up to 448 bits but uses a 64-bit block size, not 128-bit blocks, and it was not an AES finalist (Twofish was designed as Blowfish’s successor with a larger block size to address modern requirements).

In practical terms, the block size and key size characteristics matter for security and performance: 128-bit blocks are standard for modern symmetric encryption, and 256-bit keys provide a high security margin for long-term protection of sensitive logs. The mention of AES finalization also signals that this algorithm belongs to the same generation of modern block ciphers designed with strong resistance to cryptanalysis and efficient software/hardware implementation.

Therefore, based on the stated properties and its AES finalist status, the symmetric encryption algorithm is Twofish.

CEH identifies brute-force cryptanalysis as a method in which an attacker systematically tests every possible key, password, or passphrase until the correct one is found. When an attacker obtains initial bytes from an encrypted container—often referred to as known plaintext—they can use this to validate attempts as the tool iterates through candidate keys. Automated brute-force tools compare decrypted results with known header patterns, file signatures, or expected byte structures to determine when the correct key is reached. This process aligns precisely with brute-force password testing described in CEH cryptography modules. Quantum solving is not part of CEH scope, digest comparison relates to collision attacks, and analyzing output length pertains to padding oracle detection. The correct classification is automated brute-force cryptanalysis.

CEH v13 states that DNS server hijacking occurs when attackers compromise the authoritative DNS infrastructure and alter DNS zone records to redirect all legitimate queries to malicious destinations. Unlike DNS cache poisoning, which affects specific resolvers temporarily, server hijacking manipulates the core DNS authority controlling the domain. This results in a complete redirect for all users, regardless of geographic location or device configuration. CEH emphasizes that such attacks can lead to large-scale credential theft, phishing, financial fraud, and session compromise because the attacker presents an identical clone site while retaining full control of DNS routing. DNS tunneling is used for covert data exfiltration and does not redirect traffic. DNS rebinding targets browser policies, not global DNS redirection. DNS amplification is a volumetric DDoS technique unrelated to zone manipulation. The scenario matches DNS server hijacking exactly.

The correct answer is D. NTP Enumeration.

The scenario describes querying a time synchronization service and receiving information about internal client systems. This directly maps to Network Time Protocol (NTP) enumeration.

CEH-aligned enumeration material explains that NTP runs on UDP port 123 and is used to synchronize time across a network. Querying an NTP server may reveal a list of connected systems, including system names, IP addresses, and internal network information when the NTP server is placed in a DMZ or screened subnet . Another CEH reference states that NTP enumeration can reveal host information connected to the NTP server, client IP addresses, machine names, operating system information, and internal IP information depending on deployment .

Option A. NFS Enumeration is incorrect because NFS enumeration focuses on network file shares and exported directories.

Option B. NetBIOS Enumeration is incorrect because NetBIOS enumeration targets names, shares, sessions, and Windows network information.

Option C. SNMP Enumeration is incorrect because SNMP enumeration queries device management information using MIB/OID data.

Option D. NTP Enumeration is correct because the service being queried is a time synchronization service exposing client and internal network information.

Therefore, the best answer is D. NTP Enumeration.

A smart card is something you have, because it is a physical possession used for authentication. A PIN is something you know, because it is secret knowledge remembered by the user. Together, they form two-factor authentication by combining two different authentication factor categories. Fingerprints, retina scans, or facial recognition would be something you are, but those are not used in this question. Therefore, the correct answer is B.

The correct answer is C. Web Cache Poisoning Attack.

The key indicators are:

The altered content is served to other users.

The origin server still returns the legitimate response.

The issue disappears after cache expiration or replacement.

The crafted request uses headers and parameters that influence cached output.

CEH-aligned web server material explains that Web Cache Poisoning occurs when an attacker sends a crafted request into the cache and stores fake entries, causing users to be redirected or served malicious content . Another CEH-aligned reference explains that a web cache stores copies of responses to speed up future requests, and if an attacker forces malicious or manipulated content into the cache, later visitors can receive that poisoned response .

Option A. DNS Server Hijacking is incorrect because DNS records or DNS server settings are not being modified.

Option B. DNS Rebinding Attack is incorrect because the scenario concerns cached web content, not browser access to private-network resources through DNS rebinding.

Option D. SQL Injection Vulnerability is incorrect because the behavior is tied to delivery-layer caching, not database query manipulation.

Therefore, the best answer is C. Web Cache Poisoning Attack.

The correct answer is B. Inference-based assessment. In CEH vulnerability assessment concepts, an inference-based assessment starts by building an inventory of protocols discovered in the target environment. The tester then investigates the ports and services associated with those protocols and runs only the tests that are relevant to the discovered services. This exactly matches the scenario: James identified protocols, mapped ports to services such as email, web, and database services, and then selected vulnerabilities and tests appropriate for each machine. Tree-based assessment is different because it follows different assessment strategies for different components or platforms, such as Windows systems versus Linux servers. Product-based and service-based solutions refer to how vulnerability assessment tools or services are delivered, not to the protocol-and-service-driven testing logic described here. Therefore, the best CEH-aligned answer is Inference-based assessment.

The CEH Web Application Security module explains that race conditions occur when systems improperly handle simultaneous requests, leading to unexpected behavior. In token-based authentication systems, poor synchronization between token expiration checks and validation logic can allow attackers to exploit timing gaps.

The observed pattern—failed attempts with expired tokens followed by successful access—suggests the attacker exploited a race condition where the application inconsistently validated token state.

Option C is correct.

Option A would not involve expired tokens.

Option B is highly impractical given secure token entropy.

Option D typically succeeds without repeated failures.

CEH highlights race conditions as subtle but dangerous logic flaws.