VLAN Hopping Attack is a serious network security vulnerability that allows unauthorized users to gain access to VLANs they should not be able to reach. This type of attack exploits weaknesses in VLAN configuration and switch behavior to bypass network segmentation controls.
The double tagging attack is the most common VLAN hopping method. The attacker crafts a frame with two VLAN tags. The first switch removes the outer tag and forwards the frame with the inner tag to the next switch. This allows the attacker to reach VLANs they shouldn't have access to.
Switch spoofing is another dangerous VLAN hopping attack. The attacker configures their device to send Dynamic Trunking Protocol packets, making it appear as a legitimate switch. The real switch then establishes a trunk connection, giving the attacker access to all VLANs carried on that trunk.
To prevent VLAN hopping attacks, network administrators should implement several security measures. Disable Dynamic Trunking Protocol on all ports, explicitly configure trunk ports, enable port security features, and conduct regular security audits. These practices create a robust defense against VLAN hopping vulnerabilities.