Pass the The SecOps Group Security Practitioner CNSP Questions and answers with ValidTests

Port 111/TCP is the default port for the RPC (Remote Procedure Call) portmapper service on Unix systems, which registers and manages RPC services.

Why A is correct:Running rpcinfo -p queries the portmapper to list all registered RPC services, their programs, versions, and associated ports. This is a logical next step during a security audit or penetration test to identify potential vulnerabilities (e.g., NFS or NIS services). CNSP recommends this command for RPC enumeration.

Why other options are incorrect:

B. Telnet to the port to look for a banner:Telnet might connect, but RPC services don’t typically provide a human-readable banner, making this less effective than rpcinfo.

C. Telnet to the port, send "GET / HTTP/1.0" and gather information from the response:Port 111 is not an HTTP service, so an HTTP request is irrelevant and will likely fail.

D. None of the above:Incorrect, as A is a valid and recommended step.

References:CNSP "Unix Service Enumeration" (Section on RPC Services) highlights rpcinfo -p as the standard tool for probing port 111/TCP.

A DNS zone transfer replicates an entire DNS zone (a collection of DNS records for a domain) from a primary nameserver to a secondary one, typically for redundancy or load balancing. TheAXFR(Authoritative Full Zone Transfer) query type, defined in RFC 1035, facilitates this process. The dig (Domain Information Groper) tool, a staple in Linux/Unix environments, is used to query DNS servers. The correct syntax is:

dig @ axfrHere, dig @10.0.0.1 victim.com axfr instructs dig to request a zone transfer for "victim.com" from the nameserver at 10.0.0.1. The @ symbol specifies the target server, overriding the system’s default resolver.

Technical Details:

The AXFR query is sent over TCP (port 53), not UDP, due to the potentially large size of zone data, which exceeds UDP’s typical 512-byte limit (pre-EDNS0).

Successful execution requires the nameserver to permit zone transfers from the querying IP, often restricted to trusted secondaries via Access Control Lists (ACLs) for security. If restricted, the server responds with a "REFUSED" error.

Security Implications:Zone transfers expose all DNS records (e.g., A, MX, NS), making them a reconnaissance goldmine for attackers if misconfigured. CNSP likely emphasizes securing DNS servers against unauthorized AXFR requests, using tools like dig to test vulnerabilities.

Why other options are incorrect:

A. dig @10.0.0.1 victim.com axrfr:"axrfr" is a typographical error. The correct query type is "axfr." Executing this would result in a syntax error or an unrecognized query type response from dig.

B. dig @10.0.0.1 victim.com afxr:"afxr" is another typo, not a valid DNS query type per RFC 1035. dig would fail to interpret this, likely outputting an error like "unknown query type."

C. dig @10.0.0.1 victim.com arfxr:"arfxr" is also invalid, a jumbled version of "axfr." It holds no meaning in DNS protocol standards and would fail similarly.

Real-World Context:Penetration testers use dig ... axfr to identify misconfigured DNS servers. For example, dig @ns1.example.com example.com axfr might reveal subdomains or internal IPs if not locked down.References:CNSP Official Documentation (DNS Security and Tools); RFC 1035 (Domain Names - Implementation and Specification).

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.

Online attacks require real-time interaction with a target system (e.g., a login interface), whereas offline attacks occur without direct system interaction, typically after obtaining data like password hashes. A rainbow table attack is an offline method that uses precomputed tables of hash values to reverse-engineer passwords from stolen hash databases, distinguishing it from the other options, which are online.

Why B is correct:Rainbow table attacks are performed offline after an attacker has already acquired a hash (e.g., from a compromised database). The attacker matches the hash against precomputed tables to find the plaintext password, requiring no interaction with the target system during the attack. CNSP classifies this as an offline password recovery technique.

Why other options are incorrect:

A:Brute force attacks involve repeatedly submitting password guesses to a live system (e.g., via SSH or a web login), making it an online attack.

C:Password spraying attacks test a few common passwords across many accounts on a live system, also an online attack aimed at avoiding lockouts.

D:Phishing attacks trick users into submitting credentials through fake interfaces (e.g., emails or websites), requiring real-time interaction and thus classified as online.

References:CNSP "Password Attack Methodologies" (Section on Online vs. Offline Attacks) defines rainbow table attacks as offline and contrasts them with online methods like brute force and phishing.

DDoS (Distributed Denial of Service) attacks aim to overwhelm a target’s resources with excessive traffic, disrupting availability, whereas other attack types target different goals.

Why D is correct:Brute force attacks focus on guessing credentials (e.g., passwords) to gain unauthorized access, not on denying service. CNSP classifies it as an authentication attack, not a DDoS method.

Why other options are incorrect:

A:SYN Flood exhausts TCP connection resources, a classic DDoS attack.

B:NTP Amplification leverages amplified responses to flood targets, a DDoS technique.

C:UDP Flood overwhelms a system with UDP packets, another DDoS method.

References:CNSP "DDoS Attack Types" (Section on Attack Classification) excludes brute force from DDoS categories, listing SYN, NTP, and UDP floods as examples.

TCP (Transmission Control Protocol) uses a three-way handshake (SYN, SYN-ACK, ACK) toestablish connections, as per RFC 793. When a client sends a SYN packet to a port:

Open Port:The server responds with SYN-ACK.

Closed Port (no firewall):The server sends an RST (Reset) packet, often with ACK, to terminate the attempt immediately.

However, when afirewallis present, its configuration dictates the response. Modern firewalls typically operate instealth mode, using a "drop" rule for closed ports rather than a "reject" rule:

Drop:Silently discards the packet without replying, resulting inno response. The client experiences a timeout (e.g., 30 seconds), as no feedback is provided.

Reject:Sends an RST or ICMP "Port Unreachable," but this is less common for security reasons, as it confirms the firewall’s presence.

For a closed TCP port behind a firewall, "no response" (drop) is the standard behavior in secure configurations, minimizing information leakage to attackers. This aligns with CNSP’s focus on firewall best practices to obscure network topology during port scanning (e.g., with Nmap).

Why other options are incorrect:

A. A FIN and an ACK packet:FIN-ACK is used to close anestablishedTCP connection gracefully (e.g., after data transfer), not to respond to an initial SYN on a closed port.

B. RST and an ACK packet:RST-ACK is the host’s response to a closed port without a firewall. A firewall’s drop rule overrides this by silently discarding the packet.

C. A SYN and an ACK packet:SYN-ACK indicates an open port accepting a connection, the opposite of a closed port scenario.

Real-World Context:Tools like Nmap interpret "no response" as "filtered" (firewall likely present) vs. "closed" (RST received), aiding in firewall detection.References:CNSP Official Study Guide (Firewall Operations and TCP/IP); RFC 793 (TCP).

ICMP (Internet Control Message Protocol), per RFC 792, handles diagnostics (e.g., ping) and errors in IP networks. It’s exploitable in:

A. Ping of Death:

Method: Sends oversized ICMP Echo Request packets (>65,535 bytes) via fragmentation. Reassembly overflows buffers, crashing older systems (e.g., Windows 95).

Fix: Modern OSes cap packet size (e.g., ping -s 65500).

B. Smurf Attack:

Method: Spoofs ICMP Echo Requests to a network’s broadcast address (e.g., 192.168.255.255). All hosts reply, flooding the victim.

Amplification: 100 hosts = 100x traffic.

C. ICMP Flooding:

Method: Overwhelms a target with ICMP Echo Requests (e.g., ping -f), consuming bandwidth/CPU.

Variant: BlackNurse attack targets firewalls.

Technical Details:

ICMP Type 8 (Echo Request), Type 0 (Echo Reply) are key.

Mitigation: Rate-limit ICMP, disable broadcasts (e.g., no ip directed-broadcast).

Security Implications:ICMP attacks are DoS vectors. CNSP likely teaches filtering (e.g., iptables -p icmp -j DROP) balanced with diagnostics need.

Why other options are incorrect:

A, B, C individually:All are ICMP-based; D is comprehensive.

Real-World Context:Smurf attacks peaked in the 1990s; modern routers block them by default.References:CNSP Official Study Guide (Network Attacks); RFC 792 (ICMP).

Adding a user to a domain group like "Domain Admins" requires the correct command and scope (domain vs. local).

Why A is correct:net group "Domain Admins" John /add /domain adds user John to the domain-level "Domain Admins" group, per CNSP’s domain privilege management.

Why other options are incorrect:

B:net user creates users, not group memberships; syntax is wrong.

C:/admin is invalid; correct group specification is missing.

D:Targets local "Administrator" group, not domain "Domain Admins".

References:CNSP "Domain Administration" (Section on net Commands) validates net group with /domain.

SSL/TLS protocols secure network communication, but older versions have vulnerabilities:

SSLv2 (1995):Weak ciphers, no handshake integrity (e.g., MITM via DROWN attack, CVE-2016-0800). Deprecated by RFC 6176 (2011).

SSLv3 (1996):Vulnerable to POODLE (CVE-2014-3566), weak block ciphers (e.g., RC4). Deprecated by RFC 7568 (2015).

TLSv1.0 (1999, RFC 2246):Inherits SSLv3 flaws (e.g., BEAST, CVE-2011-3389), weak CBC ciphers. Deprecated by PCI DSS (2018) and RFC 8996 (2021).

TLSv1.1 (2006, RFC 4346):Improved over 1.0 but lacks modern cipher suites (e.g., AEAD). Deprecated with 1.0 by RFC 8996.

TLSv1.2 (2008, RFC 5246):Secure with strong ciphers (e.g., AES-GCM), widely used today.

TLSv1.3 (2018, RFC 8446):Latest, removes legacy weaknesses, mandatory forward secrecy.

Answer:C (A and B)—SSLv2, SSLv3, TLSv1.0, and TLSv1.1 are unsafe due to exploitable flaws. TLSv1.2 and 1.3 remain secure. CNSP likely aligns with IETF/PCI standards, mandating modern versions.

Why other options are incorrect:

A:Correct but incomplete without B.

B:Correct but incomplete without A.

D:Incorrectly includes TLSv1.2 and 1.3, which are secure and recommended.

Real-World Context:POODLE forced mass SSLv3 disablement in 2014; TLS 1.0/1.1 deprecation hit legacy systems in 2021.References:CNSP Official Documentation (Cryptographic Protocols); RFC 8996 (TLS Deprecation).

UDP (User Datagram Protocol), per RFC 768, is connectionless, lacking TCP’s handshake or acknowledgment mechanisms. When a UDP packet reaches a port:

Closed Port:The host typically sends an ICMP "Destination Port Unreachable" (Type 3, Code 3) unless suppressed (e.g., by firewall or OS settings).

Open Port:If a service is listening (e.g., DNS on 53/UDP), it processes the packet but doesn’t inherently reply unless the application protocol requires it (e.g., DNS sends a response).

Scenario:Anopen UDP port behind a firewall, with the firewall rule allowing traffic (e.g., permit udp any host 10.0.0.1 eq 123). The packet reaches the service, but UDP itself doesn’t mandate a response. Most services (e.g., NTP, SNMP) only reply if the packet matches an expected request. In this question’s generic context (no specific service),no responseis the default, as the firewall permits the packet, and the open port silently accepts it without feedback.

Security Implications:This silence makes UDP ports harder to scan (e.g., Nmap assumes "open|filtered" for no response), but exposed open ports risk amplification attacks (e.g., DNS reflection). CNSP likely contrasts UDP’s behavior with TCP for firewall rule crafting.

Why other options are incorrect:

A. ICMP message showing Port Unreachable:Occurs for closed ports, not open ones, unless the service explicitly rejects the packet (rare).

C. A SYN Packet:SYN is TCP-specific (handshake initiation), irrelevant to UDP.

D. A FIN Packet:FIN is TCP-specific (connection closure), not UDP.

Real-World Context:Testing UDP 53 (DNS) with dig @8.8.8.8 +udp yields a response, but generic UDP probes (e.g., nc -u) often get silence.References:CNSP Official Documentation (UDP and Firewall Behavior); RFC 768 (UDP).