312-50v13 ECCouncil Certified Ethical Hacker Exam (CEHv13) Free Practice Exam Questions (2025 Updated)

Comprehensive and Detailed Explanation:

Cryptographic hash functions provide:

Integrity: Any change in the input changes the output hash.

Collision Resistance: It is computationally infeasible to find two inputs that produce the same hash.

This ensures data is not altered during transmission.

From CEH v13 Courseware:

Module 10: Cryptography → Hashing Functions (e.g., SHA-256, MD5)

CEH v13 describes Agent Smith–style attacks as malicious Android operations where an app silently replaces legitimate applications by exploiting weaknesses in the Android app update and installation processes. These attacks often begin when users download seemingly innocent apps from untrusted third-party marketplaces. Once installed, the malicious application injects harmful code into other apps, overwriting them while preserving their icons and interface, allowing the attacker to harvest credentials, display ads, or maintain persistence without detection. CEH explains that this technique takes advantage of Android’s APK structure, sideloading vulnerabilities, and lack of signature validation in compromised environments. Simjacker (Option A) targets SIM toolkit vulnerabilities and does not replace apps. Man-in-the-Disk (Option B) abuses external storage operations but does not overwrite applications. Camfecting (Option D) refers to hijacking smartphone cameras. The described malicious replacement of legitimate apps exactly matches the Agent Smith attack pattern.

Command Breakdown:

nc: Netcat utility

-l: Listen mode

-u: Use UDP protocol

-p 55555: Listen on port 55555

< /etc/passwd: Redirects the contents of /etc/passwd into the socket

This means that when a connection is made to UDP port 55555, the contents of /etc/passwd will be sent to the connecting host.

From CEH v13 Courseware:

Module 8: Sniffing & Network Communication Tools

CEH v13 Study Guide states:

“Netcat can be used to serve files, open shells, or transfer data. Using input redirection, it can stream file contents to anyone who connects.”

Incorrect Options:

A: Does not log; it outputs /etc/passwd

C: The opposite; it serves the file, doesn’t grab it

D: Netcat does not delete files with this syntax

This falls under Requirement 8 of PCI DSS: "Identify and authenticate access to system components," which supports the objective of implementing strong access control measures.

CEH v13 Reference:

Module 20: Hacking Mobile Platforms and IoT – Compliance Standards

"PCI DSS requires unique identification for each person with access to ensure accountability and access control."

A vulnerability assessment is a systematic review of security weaknesses in an information system. It evaluates if the system is susceptible to any known vulnerabilities, assigns severity levels to those vulnerabilities, and recommends remediation or mitigation, if and whenever needed1. A vulnerability assessment can be performed using various tools and techniques, depending on the scope and objectives of the assessment.

Considering the potential vulnerability sources, the best initial approach to vulnerability assessment is to check for hardware and software misconfigurations to identify any possible loopholes. Hardware and software misconfigurations are common sources of vulnerabilities that can expose the system to unauthorized access, data breaches, or service disruptions. Hardware and software misconfigurations can include:

Insecure default settings, such as weak passwords, open ports, unnecessary services, or verbose error messages.

Improper access control policies, such as granting excessive privileges, allowing anonymous access, or failing to revoke access for terminated users.

Lack of encryption or authentication mechanisms, such as using plain text protocols, storing sensitive data in clear text, or transmitting data without verifying the identity of the sender or receiver.

Outdated or incompatible software versions, such as using unsupported or deprecated software, failing to apply security patches, or having software conflicts or dependencies.

Checking for hardware and software misconfigurations can help identify any possible loopholes that could be exploited by attackers to compromise the system or the data. Checking for hardware and software misconfigurations can be done using various tools, such as:

Configuration management tools, such as Ansible, Puppet, or Chef, that can automate the deployment and maintenance of consistent and secure configurations across the system.

Configuration auditing tools, such as Nipper, Lynis, or OpenSCAP, that can scan the system for deviations from the desired or expected configurations and report any issues or vulnerabilities.

Configuration testing tools, such as Inspec, Serverspec, or Testinfra, that can verify the system’s compliance with the specified configuration rules and standards.

Therefore, checking for hardware and software misconfigurations is the best initial approach to vulnerability assessment, as it can help identify and eliminate any possible loopholes that could pose a security risk to the system or the data.

SOX stands for Sarbanes-Oxley Act of 2002. It is a U.S. federal law enacted to protect shareholders and the general public from accounting errors and corporate fraud.

Key points:

Requires strict internal controls and financial disclosures in publicly traded companies.

Mandates regular audits and IT security controls related to financial data.

Applies especially to accounting systems, databases, access controls, and IT procedures related to financial reporting.

Incorrect Options:

A. PCI-DSS relates to securing credit card data.

B. FISMA pertains to federal agency cybersecurity standards.

D. ISO/IEC 27001:2013 is an international information security standard, not a legal requirement for financial integrity.

Reference – CEH v13 Official Courseware:

Module 01: Introduction to Ethical Hacking

Section: “Compliance and Legal Concepts”

Table: "Major Laws and Regulations in Information Security"

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Analyze Web Applications: Identify Files and Directories - enumerate applications, as well as hidden directories and files of the web application hosted on the web server. Tools such as ☆Gobuster is directory scanner that allows attackers to perform fast-paced enumeration of hidden files and directories of a target web application. # gobuster -u -w common.txt (wordlist) (P.1849/1833)

· Identifying operating systems, services, protocols and devices,

· Collecting unencrypted information about usernames and passwords,

· Capturing network traffic for further analysis

are passive network sniffing methods since with the help of them we only receive information and do not make any changes to the target network. When modifying and replaying the captured network traffic, we are already starting to make changes and actively interact with it.

The TTL (Time-To-Live) and TCP window size are commonly used values for passive OS fingerprinting. Different operating systems set default values for these fields in IP and TCP headers.

From CEH v13 Official Courseware and tools like Nmap and Netcraft:

A TTL of 64 and TCP window size of 5840 is a strong indicator of a Linux-based operating system.

This combination is one of the signature responses used in tools such as Nmap and p0f to fingerprint OS remotely.

Here’s a general reference table:

OS

Default TTL

TCP Window Size

Windows

128

8192/65535

Linux

64

5840

Solaris

255

8760

Mac OS

64

65535

Therefore, TTL: 64 + Window Size: 5840 = Linux OS

Incorrect Options:

A. Solaris typically has a TTL of 255 and a different window size.

B. Windows defaults to TTL 128.

C. Mac OS uses TTL 64 but has a window size of 65535.

Reference – CEH v13 Official Courseware:

Module 03: Scanning Networks

Section: “OS Detection Using TTL and TCP Window Size”

Tools: Nmap OS Fingerprinting, Xprobe2

CEH iLab: OS Fingerprinting with TCP/IP Stack Behavior

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Twofish is an encryption algorithm designed by Bruce Schneier. It’s a symmetric key block cipher with a block size of 128 bits, with keys up to 256 bits. it’s associated with AES (Advanced Encryption Standard) and an earlier block cipher called Blowfish. Twofish was actually a finalist to become the industry standard for encryption, but was ultimately beaten out by the present AES.

Twofish has some distinctive features that set it aside from most other cryptographic protocols. For one, it uses pre-computed, key-dependent S-boxes. An S-box (substitution-box) may be a basic component of any symmetric key algorithm which performs substitution. within the context of Twofish’s block cipher, the S-box works to obscure the connection of the key to the ciphertext. Twofish uses a pre-computed, key-dependent S-box which suggests that the S-box is already provided, but depends on the cipher key to decrypt the knowledge .

How Secure is Twofish?

Twofish is seen as a really secure option as far as encryption protocols go. one among the explanations that it wasn’t selected because the advanced encryption standard is thanks to its slower speed. Any encryption standard that uses a 128-bit or higher key, is theoretically safe from brute force attacks. Twofish is during this category.

Because Twofish uses “pre-computed key-dependent S-boxes”, it are often susceptible to side channel attacks. this is often thanks to the tables being pre-computed. However, making these tables key-dependent helps mitigate that risk. There are a couple of attacks on Twofish, but consistent with its creator, Bruce Schneier, it didn’t constitute a real cryptanalysis. These attacks didn’t constitue a practical break within the cipher.

Products That Use Twofish

GnuPG: GnuPG may be a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also referred to as PGP). GnuPG allows you to encrypt and sign your data and communications; it features a flexible key management system, along side access modules for all types of public key directories.

KeePass: KeePass may be a password management tool that generates passwords with top-notch security. It’s a free, open source, lightweight and easy-to-use password manager with many extensions and plugins.

Password Safe: Password Safe uses one master password to stay all of your passwords protected, almost like the functionality of most of the password managers on this list. It allows you to store all of your passwords during a single password database, or multiple databases for various purposes. Creating a database is straightforward , just create the database, set your master password.

PGP (Pretty Good Privacy): PGP is employed mostly for email encryption, it encrypts the content of the e-mail . However, Pretty Good Privacy doesn’t encrypt the topic and sender of the e-mail , so make certain to never put sensitive information in these fields when using PGP.

TrueCrypt: TrueCrypt may be a software program that encrypts and protects files on your devices. With TrueCrypt the encryption is transparent to the user and is completed locally at the user’s computer. this suggests you’ll store a TrueCrypt file on a server and TrueCrypt will encrypt that file before it’s sent over the network.

In CEH v13 Module 03: Scanning Networks, Nmap includes timing templates for controlling the speed and stealthiness of scans.

-T5: Insane mode – very fast, highly aggressive, easily detectable.

-T0: Paranoid mode – very slow and stealthy.

-O: Enables OS detection (not related to scan speed).

-A: Enables OS detection, version detection, script scanning, and traceroute (comprehensive but not specifically about speed).

Therefore:

If speed is your goal and you are not concerned about detection, then:

-T5 is the correct answer.

The ethical hacker is likely performing an SYN scan to stealthily identify open ports without fully establishing a connection. An SYN scan, also known as a half-open scan or a stealth scan, is a type of port scanning technique that exploits the TCP three-way handshake process. The hacker sends an SYN packet to a target port and waits for a response. If the target responds with an SYN/ACK packet, it means the port is open and listening for connections. If the target responds with an RST packet, it means the port is closed and not accepting connections. However, instead of completing the handshake with an ACK packet, the hacker sends an RST packet to abort the connection. This way, the hacker avoids creating a full connection and logging an entry in the target’s system, making the scan less detectable and intrusive. The hacker can repeat this process for different ports and identify which ones are open and potentially vulnerable to exploitation12.

The other options are not correct for the following reasons:

B. They are performing a TCP connect scan to identify open ports on the target machine: This option is incorrect because a TCP connect scan involves establishing a full connection with the target port by completing the TCP three-way handshake. The hacker sends an SYN packet, receives an SYN/ACK packet, and then sends an ACK packet to finalize the connection. Then, the hacker terminates the connection with an RST or FIN packet. A TCP connect scan is more reliable and compatible than an SYN scan, but also more noisy and slow, as it creates more traffic and logs on the target system12.

C. They are performing a vulnerability scan to identify any weaknesses in the target system: This option is incorrect because a vulnerability scan is a broader and deeper process than a port scan. A vulnerability scan involves identifying and assessing the security flaws and risks in a system or network, such as missing patches, misconfigurations, outdated software, or weak passwords. A vulnerability scan may use port scanning as one of its techniques, but it also uses other methods, such as banner grabbing, service enumeration, or exploit testing. A vulnerability scan usually requires more time, resources, and permissions than a port scan34.

D. They are performing a network scan to identify live hosts and their IP addresses: This option is incorrect because a network scan is a different process than a port scan. A network scan involves discovering and mapping the devices and hosts connected to a network, such as routers, switches, servers, or workstations. A network scan may use ping, traceroute, or ARP requests to identify the IP addresses, MAC addresses, and hostnames of the live hosts. A network scan usually precedes a port scan, as it provides the target range and scope for the port scan56.

Ethical hacking, as defined throughout CEH courseware, is the authorized and legitimate process of identifying vulnerabilities, weaknesses, and misconfigurations in information systems. The primary objective is to strengthen security by discovering issues before malicious actors can exploit them. Ethical hackers follow strict legal guidelines, obtain written permission, and operate within a defined scope to ensure their activities contribute positively to the organization’s security posture. Unlike malicious hacking, the intent is not to steal data, cause harm, or disrupt operations. Ethical hackers use the same tools, techniques, and methodologies that attackers use, but with the purpose of remediation and risk reduction. CEH emphasizes that ethical hacking supports defense-in-depth strategies by enabling organizations to harden their environments and proactively mitigate threats. Therefore, identifying and fixing vulnerabilities is the central mission of ethical hacking.

CEH methodology stresses prioritization based on risk, exploitability, and business impact. High-severity vulnerabilities—especially those related to outdated or unsupported server software—are frequently associated with known, publicly documented exploits. The proper next step after identifying such vulnerabilities is to confirm exploitability safely, typically by researching available exploit code, validating version-specific weaknesses, and determining whether the vulnerability can be successfully leveraged under the defined scope of engagement. CEH highlights that exploitation attempts must be evidence-driven, not arbitrary, and focusing on high-risk vulnerabilities allows testers to demonstrate meaningful security impacts. Brute-forcing (Option A) is unnecessary and high-noise. Ignoring or deprioritizing the high-risk finding (Options B and C) contradicts CEH risk-based assessment principles. Therefore, verifying exploitability of the high-risk vulnerability is the correct step.

A sniffer tool is a software or hardware device that can capture and analyze network traffic. In a switched Ethernet environment, where each port on a switch is connected to a single device, a sniffer tool can only see the traffic that is destined for or originated from the device it is attached to. However, an attacker can use various techniques to overcome this limitation and sniff the traffic of other devices on the same network. One of these techniques is MAC flooding, which exploits the finite memory of the switch’s MAC address table. The attacker sends a large number of frames with different source MAC addresses to the switch, which fills up the MAC address table and causes the switch to enter a fail-open mode, where it broadcasts all incoming frames to all ports, regardless of the destination MAC address. This way, the attacker can see all the traffic on the network and capture it with a sniffer tool.

The other options are less likely or less effective techniques for sniffing a switched Ethernet network. Compromising physical security to plug into the network directly may allow the attacker to sniff the traffic of the device they are connected to, but not the traffic of other devices on the network. Using a Trojan horse with in-built sniffing capability may allow the attacker to sniff the traffic of the infected device, but not the traffic of other devices on the network, unless the Trojan horse also performs MAC flooding or other techniques to bypass the switch. Using passive sniffing, which involves listening to the network traffic without sending any packets, may provide significant stealth advantages, but it does not help the attacker to see the traffic of other devices on the network, unless the switch is already in fail-open mode or the attacker uses other techniques to induce it. 

Comprehensive Explanation from CEH v13 Courseware:

CEH v13 underscores that modern multi-vector DDoS attacks—particularly SYN floods combined with Layer 7 HTTP floods—cannot be effectively mitigated by traditional firewalls, IPS devices, or local traffic filters. These systems become overwhelmed or risk blocking legitimate clients. CEH emphasizes the use of cloud-based DDoS mitigation platforms that provide traffic scrubbing, distributed filtering, rate shaping, and automatic scaling to absorb massive volumes of malicious traffic. Such services differentiate legitimate versus malicious traffic using global intelligence, behavioral analysis, and multi-layer protection strategies. Increasing bandwidth or blocking broad traffic categories is ineffective and harmful to users. An IPS cannot scale to handle volumetric attacks. Only cloud scrubbing solutions (e.g., Cloudflare, Akamai, AWS Shield Advanced) meet CEH’s recommended defenses for high-volume distributed attacks. These services ensure continuous availability and minimize collateral damage by filtering traffic upstream before it reaches the organization's infrastructure.

Social engineering is the term used for a broad range of malicious activities accomplished through human interactions. It uses psychological manipulation to trick users into making security mistakes or giving away sensitive information.

Social engineering attacks typically involve some form of psychological manipulation, fooling otherwise unsuspecting users or employees into handing over confidential or sensitive data. Commonly, social engineering involves email or other communication that invokes urgency, fear, or similar emotions in the victim, leading the victim to promptly reveal sensitive information, click a malicious link, or open a malicious file. Because social engineering involves a human element, preventing these attacks can be tricky for enterprises.

In CEH v13 Module 10: Vulnerability Assessment, the Vulnerability Management Lifecycle is defined with the following structured steps:

Identify assets & baseline (Step 2)

Vulnerability scanning (Step 5)

Risk assessment/prioritization (Step 6)

Remediation (Step 1)

Verification (Step 3)

Continuous monitoring (Step 4)

So the correct lifecycle flow is:

2 → 5 → 6 → 1 → 3 → 4

This ensures vulnerabilities are identified, assessed, remediated, validated, and monitored on an ongoing basis.

Passive sniffing refers to listening to or capturing network traffic without sending any packets or altering the communication stream. The attacker’s system operates in "promiscuous mode" to monitor all traffic flowing through the network segment. This technique is mostly used in environments like hub-based or unencrypted Wi-Fi networks, where traffic is visible to all systems.

According to the CEH v13 Official Courseware, Module 08: Sniffing, under the subsection "Passive Sniffing", the following capabilities are associated with passive sniffing:

Capturing unencrypted credentials (usernames and passwords)

Identifying protocols, services, IP addresses, and hostnames

Monitoring HTTP sessions, cookies, and other clear-text traffic

Gathering detailed information for fingerprinting and enumeration

Exporting traffic to PCAPs for forensic and offline analysis

However, passive sniffing does not involve any active interference with the traffic. Therefore, actions like “modifying and replaying” packets require an attacker to craft and inject packets into the network — this is considered active sniffing or traffic manipulation, which is out of scope for passive techniques.

Thus:

Option A: Valid for passive sniffing (host discovery via captured traffic)

Option B: Invalid for passive sniffing (requires active traffic manipulation)

Option C: Valid (if data is unencrypted)

Option D: Valid (captures traffic for offline review)

Reference – CEH v13 Official Courseware:

Module 08: Sniffing

Section: “Passive Sniffing vs Active Sniffing”

Study Guide Pages: Usually found under “Types of Sniffing Techniques”

CEH iLabs/Engage Scenarios: Packet capture and Wireshark lab modules

The most effective long-term strategy to reduce the gap between black hats and white hats is through education. Training individuals in areas such as:

Risk analysis

Vulnerability identification

Defensive mechanisms and countermeasures

helps foster a deeper understanding of cybersecurity and ethical responsibilities.

From CEH v13 Official Guide:

Module 1: Introduction to Ethical Hacking

Section: Ethics and Legal Issues

Subsection: Bridging the Hacker Mindset

The guide states:

“Educating individuals on proper cybersecurity techniques and the consequences of malicious hacking is critical to transforming the skillset of potential black hats into productive white hat professionals. Providing structured knowledge through training, books, and ethical hacking certifications empowers aspiring hackers to use their skills positively.”

Incorrect Options:

B: Useful for operations, but doesn’t bridge a knowledge gap.

C: Lowering certification standards can reduce industry credibility.

D: Involves a specific audience and doesn't address the broader knowledge gap.

From CEH v13 Module 03: Scanning Networks, OS fingerprinting with Nmap (using the -O option) requires privileged access to craft raw packets (especially SYN, ACK, and ICMP). On Unix/Linux systems:

Root privileges are mandatory to perform TCP/IP stack fingerprinting.

If Nmap is run as a normal user, it fails to initiate OS scanning and exits with a message like “QUITTING!”.

So, in this case, the scan fails because the shell opened does not have elevated (root) privileges.

https://en.wikipedia.org/wiki/Salt_(cryptography)

A salt is random data that is used as an additional input to a one-way function that hashes data, a password, or passphrase. Salts are used to safeguard passwords in storage. Historically a password was stored in plaintext on a system, but over time additional safeguards were developed to protect a user's password against being read from the system. A salt is one of those methods.

A new salt is randomly generated for each password. In a typical setting, the salt and the password (or its version after key stretching) are concatenated and processed with a cryptographic hash function, and the output hash value (but not the original password) is stored with the salt in a database. Hashing allows for later authentication without keeping and therefore risking exposure of the plaintext password in the event that the authentication data store is compromised.

Salts defend against a pre-computed hash attack, e.g. rainbow tables. Since salts do not have to be memorized by humans they can make the size of the hash table required for a successful attack prohibitively large without placing a burden on the users. Since salts are different in each case, they also protect commonly used passwords, or those users who use the same password on several sites, by making all salted hash instances for the same password different from each other.

In the Windows security model, SID ending in -500 is reserved for the built-in Administrator account. The SID seen in the image:

S-1-5-21-343818398-789336058-1343024091-500 → maps to user Joe

This proves that Joe is the true built-in administrator account on the domain EARTH.

From CEH v13 Courseware:

Module 4: Enumeration

Topic: SID Enumeration and Account Discovery

CEH v13 Study Guide states:

“In Windows, the account with RID 500 is always the default Administrator account. Even if renamed, its SID remains ending in -500. Enumeration of this SID allows attackers to identify privileged accounts.”

Incorrect Options:

A: Incomplete — it is not just that Joe has SID 500, but that SID 500 means Joe is the administrator.

B/C: These commands don’t validate Guest account status.

E: Incorrect — these commands explicitly prove administrator identity.

In authentication, Multi-Factor Authentication (MFA) involves using more than one category of authentication factors:

Something you know (e.g., password)

Something you have (e.g., RFID badge, token)

Something you are (e.g., biometrics like fingerprints, facial recognition, gait)

In this scenario:

The RFID badge is "something you have" (a physical object).

The gait recognition (walking pattern) captured by the camera is a biometric—"something you are" (a physical characteristic).

Together, these two methods represent two distinct authentication factors, thereby implementing true multi-factor authentication.

Reference – CEH v13 Official Study Guide:

Module 5: System Hacking

Topic: Authentication Mechanisms

Quote:

“Examples of multi-factor authentication include combining biometrics (something you are) with a smart card or badge (something you have). Gait recognition is considered a behavioral biometric and falls under ‘something you are’.”

Incorrect Options Explained:

A. Incorrect — gait and RFID represent two separate factor types, not one.

C. No evidence in the scenario supports high false positives.

D. Gait analysis is a recognized biometric method and can be used for identification.

Sniffing attacks are a type of network attack that involves intercepting and analyzing data packets as they travel over a network. Sniffing attacks can be used to steal sensitive information, such as usernames, passwords, credit card numbers, etc. Sniffing attacks can also be used to perform reconnaissance, spoofing, or man-in-the-middle attacks.

The IT department of the company has implemented some security measures to prevent or mitigate sniffing attacks, such as:

Adding the MAC address of the gateway to the ARP cache: This prevents ARP spoofing, which is a technique that allows an attacker to redirect network traffic to their own device by sending fake ARP messages that associate their MAC address with the IP address of the gateway.

Switching to IPv6 instead of IPv4: This reduces the risk of IP spoofing, which is a technique that allows an attacker to send packets with a forged source IP address, pretending to be another device on the network.

Using encrypted sessions such as SSH instead of Telnet, and Secure File Transfer Protocol instead of FTP: This protects the data from being read or modified by an attacker who can capture the packets, as the data is encrypted and authenticated using cryptographic protocols.

However, these measures are not enough to completely eliminate the threat of sniffing, as an attacker can still use other techniques, such as:

Passive sniffing: This involves monitoring the network traffic without injecting any packets or altering the data. Passive sniffing can be done on a shared network, such as a hub, or on a switched network, using techniques such as MAC flooding, port mirroring, or VLAN hopping.

Active sniffing: This involves injecting packets or modifying the data to manipulate the network behavior or gain access to more traffic. Active sniffing can be done using techniques such as DHCP spoofing, DNS poisoning, ICMP redirection, or TCP session hijacking.

Therefore, the next step to enhance network security is to implement network scanning and monitoring tools, which can help detect and prevent sniffing attacks by:

Scanning the network for unauthorized devices, such as rogue access points, hubs, or sniffers, and removing them or isolating them from the network.

Monitoring the network for abnormal traffic patterns, such as excessive ARP requests, DNS queries, ICMP messages, or TCP connections, and alerting the network administrators or blocking the suspicious sources.

Analyzing the network traffic for malicious content, such as malware, phishing, or exfiltration, and filtering or quarantining the infected or compromised devices.

Hootsuite may be a social media management platform that covers virtually each side of a social media manager’s role.

With only one platform users area unit ready to do the easy stuff like reverend cool content and schedule posts on social media in all the high to managing team members and measure ROI.

There area unit many totally different plans to decide on from, from one user set up up to a bespoken enterprise account that’s appropriate for much larger organizations.

Conducting location search on social media sites such as Twitter, Instagram, and Facebook helps attackers to detect the geolocation of the target. This information further helps attackers to perform various social engineering and non-technical attacks. Many online tools such as Followerwonk, Hootsuite, and Sysomos are available to search for both geotagged and non-geotagged information on social media sites. Attackers search social media sites using these online tools using keywords, usernames, date, time, and so on...

The official management decision given by a senior agency official to authorize operation of an information system and to explicitly accept the risk to agency operations (including mission, functions, image, or reputation), agency assets, or individuals, based on the implementation of an agreed-upon set of security controls.

formal declaration by a designated accrediting authority (DAA) or principal accrediting authority (PAA) that an information system is approved to operate at an acceptable level of risk, based on the implementation of an approved set of technical, managerial, and procedural safeguards. See authorization to operate (ATO). Rationale: The Risk Management Framework uses a new term to refer to this concept, and it is called authorization.

Identifies the information resources covered by an accreditation decision, as distinguished from separately accredited information resources that are interconnected or with which information is exchanged via messaging. Synonymous with Security Perimeter.

For the purposes of identifying the Protection Level for confidentiality of a system to be accredited, the system has a conceptual boundary that extends to all intended users of the system, both directly and indirectly connected, who receive output from the system. See authorization boundary. Rationale: The Risk Management Framework uses a new term to refer to the concept of accreditation, and it is called authorization. Extrapolating, the accreditation boundary would then be referred to as the authorization boundary.

In CEH v13 Module 14: Cryptography, VPN (Virtual Private Network) technology is described as the method that allows users to securely transmit data over an insecure (public) network by establishing a secure, encrypted tunnel.

VPN Features:

Encrypts all traffic between the user's device and the target network.

Prevents session hijacking, eavesdropping, and man-in-the-middle (MITM) attacks.

Common protocols: IPSec, L2TP, SSL VPN, and OpenVPN.

Option Clarification:

A. DMZ: A network segmentation strategy, not an encryption method.

B. SMB signing: Ensures integrity for SMB protocol, but not for remote tunneling.

C. VPN: Correct. Used to securely tunnel over public networks.

D. Switch network: Refers to network segmentation using switches, unrelated to tunneling.

https://en.wikipedia.org/wiki/Residual_risk

The residual risk is the risk or danger of an action or an event, a method or a (technical) process that, although being abreast with science, still conceives these dangers, even if all theoretically possible safety measures would be applied (scientifically conceivable measures); in other words, the amount of risk left over after natural or inherent risks have been reduced by risk controls.

· Residual risk = (Inherent risk) – (impact of risk controls)