SY0-701 Question 73
Single answerUnsecure networks: Wireless , Wired , Bluetooth , Open service ports , Default credentialsA security administrator is reviewing a small branch office after a report that an unknown person was seen sitting in the parking lot with a laptop near the building. During the review, the administrator finds that the wireless access point is still using the vendor's default administrator password, the guest Wi-Fi uses WPA2 with a strong passphrase, several unused switch ports in the lobby are active, and a network scan shows TCP port 23 open on an old networked HVAC controller. Which finding presents the MOST immediate risk of unauthorized internal network access from outside the building?
- A
The wireless access point is using the vendor's default administrator password
- B
The guest Wi-Fi uses WPA2 with a strong passphrase
- C
Several unused switch ports in the lobby are still active
- D
TCP port 23 is open on the networked HVAC controller
Show answer and explanation
Correct answer: A
Explanation
The best answer is the wireless access point using the vendor's default administrator password. In Security+ terms, default credentials on infrastructure devices are a critical weakness because they are widely documented, frequently automated in attack tools, and can lead to immediate compromise of network access controls. In this scenario, the attacker is positioned outside the building, making wireless infrastructure the most relevant entry point. While active wired ports and an open Telnet service are both valid findings, they are either less directly accessible from the parking lot or represent a secondary path. Best practices from CIS Controls, NIST hardening guidance, and vendor security recommendations consistently emphasize changing default passwords, disabling unnecessary services such as Telnet, and restricting physical and logical network access through measures such as port security, segmentation, and secure management protocols.
- A. Correct.
Correct. A wireless access point using a default administrator password is a high-risk condition because an attacker who can reach the management interface could log in with publicly known credentials and change settings such as SSIDs, security modes, DNS, routing, or remote management options. In a real scenario, someone in the parking lot could attempt to associate to the wireless network or reach the AP management interface if it is exposed over Wi-Fi. Default credentials remain one of the most common and easily exploited weaknesses, and changing them is a basic hardening step recommended by vendors and security baselines.
- B. Incorrect.
Incorrect. WPA2 with a strong passphrase is generally an appropriate security control for guest wireless access, assuming proper segmentation is also in place. This choice is plausible because wireless networks are often targeted from outside the building, but the scenario does not indicate weak encryption, an open SSID, or credential reuse. By itself, this is not the most immediate risk described.
- C. Incorrect.
Incorrect. Active unused switch ports are a security issue because they can allow unauthorized wired access if someone can physically connect to them. However, this typically requires direct physical access inside the lobby or building. In this scenario, the suspicious activity was observed from outside the building, so this is a concern but not the most immediate external access risk compared with a wireless device using default admin credentials.
- D. Incorrect.
Incorrect. An open Telnet port on an HVAC controller is a serious security concern because Telnet is insecure, transmits data in cleartext, and often indicates legacy management exposure. It increases attack surface and should be remediated, typically by disabling Telnet and using secure management methods where possible. However, the question asks about the most immediate risk of unauthorized internal network access from outside the building. The default password on the wireless access point is more directly aligned with that threat because it can enable rapid takeover of wireless infrastructure.