Certified Ethical Hacker CEH · Free Practice Question Hard
Question 31
You are planning to exploit a network-based vulnerability against an organization as part of a penetration test. You attempted to connect your laptop to the network jack in their conference room. You found yourself in the highly restricted VLAN that the organization allows its visitors to connect to when conducting presentations. This VLAN only allows you to access the internet, not the internal network. You decide you need to conduct VLAN hopping. Which of the following methods would be MOST likely to succeed?
- A Spoof the MAC address of the room's VOIP phone to your laptop
- B Poison or overflow the MAC table of the switch
- C Connect a wireless access point to the conference room's network jack
- D Harvest the user credentials of an employee and use those to connect
Reveal correct answer
Correct answer: B
Explanation
OBJ-4.1: VLAN hopping is the act of illegally moving from one VLAN to another. A VLAN (virtual LAN) is a logical grouping of switch ports extending across any number of switches on an Ethernet network. One of the most common VLAN hopping methods is to overflow the MAC table on a vulnerable switch. When this occurs, the switch defaults to operating as a hub and repeats all frames being received through all of its ports. This "fail open" method ensures the network can continue to operate, but it is a security risk that can be exploited by the penetration tester.Discussion
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