CNSP Exam Dumps - Certified Network Security Practitioner (CNSP)

UDP is a connectionless protocol, and its behavior when a packet reaches a port depends on whether the port is open or closed. Without a firewall altering the response, the standard protocol applies.

Why A is correct:When a UDP packet is sent to a closed port, the host typically responds with an ICMP Type 3 (Destination Unreachable), Code 3 (Port Unreachable) message, indicating no service is listening. CNSP notes this as a key indicator in port scanning.

Why other options are incorrect:

B:RST packets are TCP-specific, not used in UDP.

C:No response occurs for open UDP ports unless an application replies, not closed ports.

D:A is correct, so "none of the above" is invalid.

References:CNSP "Network Scanning Techniques" (Section on UDP Responses) confirms ICMP Port Unreachable as the standard response for closed UDP ports.

In Linux/Unix, theSUID (Set User ID)bit allows a program to execute with the owner’s permissions, typically root, rather than the caller’s. It’s denoted by an s in the user execute field (e.g., -rwsr-xr-x). Common SUID programs perform privileged tasks requiring temporary elevation.

Analysis:

C. /usr/bin/passwd:

Purpose: Updates user passwords in /etc/shadow (root-owned, 0600 perms).

Permissions: Typically -rwsr-xr-x, owned by root. The SUID bit lets non-root users modify shadow securely.

Command: ls -l /usr/bin/passwd confirms SUID (s in user execute).

A. /bin/ls:

Purpose: Lists directory contents, no privileged access needed.

Permissions: -rwxr-xr-x (no SUID).Runs as the calling user.

B. /usr/bin/curl:

Purpose: Transfers data over HTTP/FTP, no root privileges required by default.

Permissions: -rwxr-xr-x (no SUID).

Technical Details:

SUID Bit: Set via chmod u+s <file> or chmod 4755.

Security: SUID binaries are audited (e.g., find / -perm -u=s) due to escalation risks if writable or poorly coded (e.g., buffer overflows).

Security Implications:CNSP likely highlights SUID as an attack vector (e.g., CVE-1996-0095 exploited passwd flaws). Hardening removes unnecessary SUID bits.

Why other options are incorrect:

A, B:Lack SUID; no privileged operations.

D:Incorrect, as /usr/bin/passwd is a SUID example.

Real-World Context:SUID on /bin/su or /usr/bin/sudo similarly enables privilege escalation, often targeted in exploits.References:CNSP Official Documentation (Linux Security); Linux File Permissions Guide.

Negotiating a shared encryption key involves a process where two parties agree on a secret key over an insecure channel without directly transmitting it. This is distinct from encryption or hashing algorithms, which serve different purposes.

Why C is correct:The Diffie-Hellman (DH) algorithm is a key exchange protocol that enables two parties to establish a shared secret key using mathematical operations (e.g., modular exponentiation). It’s widely used in protocols like TLS and IPsec, as noted in CNSP for secure key negotiation.

Why other options are incorrect:

A:Triple-DES is a symmetric encryption algorithm for data encryption, not key negotiation.

B:SHA1 is a hash function for integrity, not key exchange.

D:AES is a symmetric encryption algorithm, not a key exchange mechanism.

References:CNSP "Cryptographic Protocols" (Section on Key Exchange) describes Diffie-Hellman as the standard for shared key negotiation, contrasting it with encryption algorithms.

ASilver Ticketis a forged KerberosService Ticket (TGS - Ticket Granting Service)in ActiveDirectory, granting access to a specific service (e.g., MSSQL, CIFS) without KDC interaction. Unlike a Golden Ticket (TGT forgery), it requires:

Service Account’s NTLM Hash:The target service’s account (e.g., MSSQLSvc) hash, not a ticket.

Forgery: Tools like Mimikatz craft the TGS (e.g., kerberos::golden /service: /user:<user> /ntlm:).

Kerberos Flow (RFC 4120):

TGT (Ticket-Granting Ticket): Obtained via AS (Authentication Service) with user creds.

TGS: Requested from TGS (Ticket Granting Service) using TGT for service access.

Silver Ticket Process:

No TGT needed; the attacker mimics the TGS step using the service account’s stolen hash (e.g., from a compromised host).

C. Service Account Ticket:Misnomer—it’s the hash of the service account (e.g., MSSQLSvc) that enables forgery, not a pre-existing ticket. CNSP’s phrasing likely tests this nuance.

Security Implications:Silver Tickets are stealthier than Golden Tickets (service-specific, shorter-lived). CNSP likely stresses hash protection (e.g., LAPS) and Kerberos monitoring.

Why other options are incorrect:

A. Session Ticket:Not a Kerberos term; confuses session keys.

B. TGT:Used for Golden Tickets, not Silver.

D:Incorrect; the service account’s hash (implied by “ticket”) is essential.

Real-World Context:Silver Tickets exploited in APT29 attacks (2020 SolarWinds) for lateral movement.References:CNSP Official Documentation (Kerberos Attacks); RFC 4120 (Kerberos).

An IP address with a/18prefix (CIDR notation) indicates 18 network bits in the subnet mask, leaving 14 host bits (32 total bits - 18). For IPv4 (e.g., 192.168.0.1):

Binary Mask:First 18 bits are 1s, rest 0s.

1st octet: 11111111 (255)

2nd octet: 11111111 (255)

3rd octet: 11000000 (192)

4th octet: 00000000 (0)

Decimal:255.255.192.0

Calculation:

Bits: /18 = 2^14 hosts (16,384), minus 2 (network/broadcast) = 16,382 usable.

Range: 192.168.0.0–192.168.63.255 (3rd octet: 0–63, as 192 = 11000000 covers 6 bits).

Technical Details:

Subnet masks align on octet boundaries or mid-octet (e.g., 192 = 2^7 + 2^6).

Contrast: /24 = 255.255.255.0 (256 hosts), /16 = 255.255.0.0 (65,536 hosts).

Security Implications:Larger subnets (e.g., /18) increase broadcast domains, risking amplification attacks. CNSP likely teaches subnetting for segmentation (e.g., VLANs).

Why other options are incorrect:

A. 255.255.255.0:/24 (8 host bits), not /18.

B. 255.225.225.0:Invalid mask (225 = 11100001, non-contiguous 1s).

D. 255.225.192.0:Invalid (225 breaks binary sequence).

Real-World Context:Subnetting 192.168.0.0/18 isolates departments in enterprise networks.References:CNSP Official Documentation (IP Addressing); RFC 1918 (Private IP).