VLAN Hopping Attacks

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Unit: 9 Lesson: 3

what am i a frog

VLAN hopping is designed to send packets that escape the current VLAN. This is done by either double tagging or using a malicious switch to route packets and to perform inter-VLAN sniffing. This exploits the main feature of 802.1Q.

Double Tagging (Raw Lesson Content)

Default VLANs are designed to provide compatibility with non-VLAN capable switches. The attacker, using a device placed in the default VLAN, crafts a frame with two VLAN tag headers. The first trunk switch to inspect the frame strips the first header, and the frame gets forwarded to the target VLAN. Such an attack can only send packets one way but could be used to perform a DoS attack against a host on a different VLAN.

STP Manipulation Attacks (Raw Lesson Content)

STP is normally configured on a network with several switches. The primary purpose is to prevent switching loops. To make STP work, a single switch is designated as the root bridge. If an attacker can become the root bridge, they are then able to see a variety of frames that they normally wouldn't see. To perpetrate this attack, the attacker inserts their switch into the tree and manipulates it to appoint their switch as the root bridge. By doing this, they can use a sniffer to collect data traversing the network.

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