The correct answer is that the firewall may allow IP spoofing if antispoofing is not enabled. This vulnerability arises because the Cisco ASA firewall configuration permits traffic from RFC 1918 private IP addresses on the inside interface to the outside interface using the inspect command for HTTP and FTP, but without any explicit antispoofing or Unicast Reverse Path Forwarding (uRPF) check. Without these safeguards, the ASA does not verify that the source IP actually belongs to the inside network, allowing an attacker on the inside to spoof source addresses and bypass the security boundary. On the Cisco SCOR / CCNP Security Core 350-701 exam, this tests your understanding of how stateful inspection alone does not prevent spoofing—you must explicitly enable antispoofing or uRPF. A common trap is assuming the inspect command inherently validates source addresses; it does not. Memory tip: “Inspect inspects content, not the source—always pair it with antispoofing to keep spoofing out.”
350-701 Security Concepts Practice Question
This 350-701 practice question tests your understanding of security concepts. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
During a security audit, a penetration tester discovers that a Cisco ASA firewall is configured with a rule that permits traffic from the inside interface with a source IP address in the RFC 1918 range to the outside interface. The rule uses the 'inspect' command for HTTP and FTP. Which potential vulnerability does this configuration introduce?
Why wrong: FTP inspection does not permit anonymous login; it handles NAT and state tracking for FTP.
B
The configuration allows traffic without network address translation (NAT)
Why wrong: Lack of NAT is not a vulnerability; it may be intentional for internal networks.
C
The HTTP inspection may allow SQL injection attacks to bypass the firewall
Why wrong: HTTP inspection does not inherently allow SQL injection; it parses HTTP traffic but does not prevent application-layer attacks like SQL injection.
D
The firewall may allow IP spoofing if antispoofing is not enabled
Permitting RFC 1918 addresses from the inside without antispoofing checks can allow an attacker to spoof internal IP addresses.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The firewall may allow IP spoofing if antispoofing is not enabled
Option D is correct because the configuration permits traffic from RFC 1918 private IP addresses on the inside interface to the outside interface without any explicit antispoofing or Unicast Reverse Path Forwarding (uRPF) check. This allows an attacker on the inside network to spoof source IP addresses that appear to come from the inside subnet, bypassing the firewall's intended security boundary. Without antispoofing, the ASA will not verify that the source IP actually belongs to the inside network, enabling IP spoofing attacks.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
FTP inspection permits anonymous login commands
Why it's wrong here
FTP inspection does not permit anonymous login; it handles NAT and state tracking for FTP.
✗
The configuration allows traffic without network address translation (NAT)
Why it's wrong here
Lack of NAT is not a vulnerability; it may be intentional for internal networks.
✗
The HTTP inspection may allow SQL injection attacks to bypass the firewall
Why it's wrong here
HTTP inspection does not inherently allow SQL injection; it parses HTTP traffic but does not prevent application-layer attacks like SQL injection.
✓
The firewall may allow IP spoofing if antispoofing is not enabled
Why this is correct
Permitting RFC 1918 addresses from the inside without antispoofing checks can allow an attacker to spoof internal IP addresses.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that 'inspect' commands automatically provide full security, when in reality they only perform stateful inspection and protocol compliance, not antispoofing or anti-spoofing protections like uRPF.
Detailed technical explanation
How to think about this question
The Cisco ASA uses interface-level antispoofing by default when Unicast RPF is enabled, which checks that the source IP of incoming packets matches the routing table entry for the return path. Without this, an attacker on the inside can send packets with a spoofed source IP (e.g., a public IP or another internal IP) to the outside, making the firewall believe the traffic is legitimate. In a real-world scenario, this could be used to launch a reflected DDoS attack or bypass ACLs that rely on source IP trust.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The firewall may allow IP spoofing if antispoofing is not enabled — Option D is correct because the configuration permits traffic from RFC 1918 private IP addresses on the inside interface to the outside interface without any explicit antispoofing or Unicast Reverse Path Forwarding (uRPF) check. This allows an attacker on the inside network to spoof source IP addresses that appear to come from the inside subnet, bypassing the firewall's intended security boundary. Without antispoofing, the ASA will not verify that the source IP actually belongs to the inside network, enabling IP spoofing attacks.
What should I do if I get this 350-701 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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