312-50v13 Exam Dumps - Certified Ethical Hacker Exam (CEHv13)

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

This is a fairly simple question. You must to understand what a subnet mask is and how it works.

A subnetwork or subnet is a logical subdivision of an IP network.The practice of dividing a network into two or more networks is called subnetting.

Computers that belong to the same subnet are addressed with an identical most-significant bit-group in their IP addresses. This results in the logical division of an IP address into two fields: the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.

The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix.

For IPv4, a network may also be characterized by its subnet mask or netmask, which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is the subnet mask for the prefix 198.51.100.0/24.

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

Remote Authentication Dial-In User Service (RADIUS) is a networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service.

RADIUS is a client/server protocol that runs in the application layer, and can use either TCP or UDP. Network access servers, which control access to a network, usually contain a RADIUS client component that communicates with the RADIUS server. RADIUS is often the back-end of choice for 802.1X authentication. A RADIUS server is usually a background process running on UNIX or Microsoft Windows.

Authentication and authorization

The user or machine sends a request to a Network Access Server (NAS) to gain access to a particular network resource using access credentials. The credentials are passed to the NAS device via the link-layer protocol—for example, Point-to-Point Protocol (PPP) in the case of many dialup or DSL providers or posted in an HTTPS secure web form.

In turn, the NAS sends a RADIUS Access Request message to the RADIUS server, requesting authorization to grant access via the RADIUS protocol.

This request includes access credentials, typically in the form of username and password or security certificate provided by the user. Additionally, the request may contain other information which the NAS knows about the user, such as its network address or phone number, and information regarding the user's physical point of attachment to the NAS.

The RADIUS server checks that the information is correct using authentication schemes such as PAP, CHAP or EAP. The user's proof of identification is verified, along with, optionally, other information related to the request, such as the user's network address or phone number, account status, and specific network service access privileges. Historically, RADIUS servers checked the user's information against a locally stored flat-file database. Modern RADIUS servers can do this or can refer to external sources—commonly SQL, Kerberos, LDAP, or Active Directory servers—to verify the user's credentials.

The RADIUS server then returns one of three responses to the NAS:

1) Access-Reject,

2) Access-Challenge,

3) Access-Accept.

Access-Reject

The user is unconditionally denied access to all requested network resources. Reasons may include failure to provide proof of identification or an unknown or inactive user account.

Access-Challenge

Requests additional information from the user such as a secondary password, PIN, token, or card. Access-Challenge is also used in more complex authentication dialogs where a secure tunnel is established between the user machine and the Radius Server in a way that the access credentials are hidden from the NAS.

Access-Accept

The user is granted access. Once the user is authenticated, the RADIUS server will often check that the user is authorized to use the network service requested. A given user may be allowed to use a company's wireless network, but not its VPN service, for example. Again, this information may be stored locally on the RADIUS server or may be looked up in an external source such as LDAP or Active Directory.

A Kerberoasting attack is a technique that exploits the weak encryption of Kerberos service tickets to obtain the password hashes of service accounts that have a Service Principal Name (SPN) associated with them. The attacker can then crack the hashes offline and use the plaintext passwords to impersonate the service accounts and access network resources.

A Kerberoasting attack follows these steps1:

The attacker impersonates a legitimate Active Directory user and authenticates to the Key Distribution Center (KDC) in the Active Directory environment. They then request a Ticket Granting Ticket (TGT) from the KDC to access network resources. The KDC complies because the attacker is impersonating a legitimate user.

The attacker enumerates the service accounts that have an SPN using tools like GetUserSPNs.py or PowerView. They then request a service ticket for each SPN from the KDC using their TGT. The KDC grants the service tickets, which are encrypted with the password hashes of the service accounts.

The attacker captures the service tickets and takes them offline. They then attempt to crack the password hashes using tools like Hashcat or John the Ripper. They can use various methods, such as brute force, dictionary, or hybrid attacks, to guess the passwords. Alternatively, they can use a PRINCE attack, which is a probabilistic password generation technique that combines common words, patterns, and transformations to generate likely passwords2.

Once the attacker obtains the plaintext passwords of the service accounts, they can use them to authenticate as the service accounts and access the network resources that they are authorized to.

Therefore, the next step that the analyst should take after obtaining a valid TGT is to request a service ticket for the SPN of the target service account. This will allow them to capture the service ticket and extract the password hash of the service account.

Firewalk, covered in CEH v13 Module 03, is a firewall analysis tool that uses TTL-limited probes to determine which ports are allowed through a filtering device (firewall/router).

If a Time-to-Live Exceeded message is received, it means the packet made it past the firewall and was stopped before reaching the target host.

No response typically means filtered or blocked.

Therefore:

Ports 21 and 22 are filtered by the firewall.

Port 23 triggered a TTL Exceeded, meaning it passed through the firewall, and likely hit a router or was dropped due to TTL=0 before reaching the host.

Wireshark is the primary packet-sniffing tool covered in CEH v13 Network Sniffing. It captures and analyzes live traffic, allowing analysts to view plaintext HTTP packets.

Nessus is a vulnerability scanner, Nmap is for scanning, Netcat is a networking utility. None provide protocol-level inspection like Wireshark.

Thus, Option D is correct.

CHNTPW (Change NT Password) is a Linux-based utility that allows attackers or administrators to:

Reset Windows user account passwords

Unlock disabled or locked user accounts

Remove password protection without knowing the original password

It works by editing the Windows SAM (Security Account Manager) file located in the Windows system directory.

Reference – CEH v13 Official Study Guide:

Module 5: System Hacking

Quote:

“CHNTPW is a tool that can reset or change passwords on Windows systems by directly editing the SAM database. It is commonly run from a Linux LiveCD.”

Incorrect Options:

A. John the Ripper is for cracking passwords, not resetting them directly.

B. SET (Social Engineering Toolkit) is for phishing and payloads, not password resets.

D. Cain & Abel is a password recovery tool for Windows but runs on Windows, not Linux.

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Cross-Site Request Forgery (CSRF) is covered in CEH v13 Module 12: Hacking Web Applications. It occurs when an attacker tricks a victim’s browser into making unintended, authenticated requests to a web application where the victim is already logged in.

Example:

User logs in to a banking site.

While logged in, the attacker sends the user a crafted link that submits a transaction via a hidden request.

Since the user’s session cookies are valid, the bank processes the request.

Why Other Options Are Incorrect:

A. Session hijacking: Steals session tokens but doesn’t involve forcing browser actions.

B. SSRF: Server sends a request to an internal service, not via user's browser.

D. XSS: Executes scripts in the user’s browser but doesn't force HTTP requests under the user’s identity.

True Positive - IDS referring a behavior as an attack, in real life it is

True Negative - IDS referring a behavior not an attack and in real life it is not

False Positive - IDS referring a behavior as an attack, in real life it is not

False Negative - IDS referring a behavior not an attack, but in real life is an attack.

False Negative - is the most serious and dangerous state of all !!!!