Which attack adds and modifies tags in the Ethernet frame to allow traffic flow through any VLAN?

Which attack adds and modifies tags in the Ethernet frame to allow traffic flow through any VLAN?

• A. Switch Spoofing
• B. ICMP Router Discovery Protocol (IRDP)
• C. double tagging
• D. VLAN hopping

Answer: (C)

Manipulating VLAN tags on Ethernet frames to cross VLAN boundaries relies on how 802.1Q tagging works on trunk links. In the double tagging method, an attacker sends a frame with two VLAN tags: an outer tag that matches the trunk’s native VLAN and an inner tag for the target VLAN. When this frame traverses switches on a trunk, the outer tag is stripped (because it’s seen as the native VLAN), leaving the inner tag to direct the frame into the target VLAN on subsequent switches. This allows traffic to flow into the desired VLAN despite segmentation, effectively bypassing VLAN boundaries. This precise use of two tags is why the approach is described as double tagging. The other options describe different attack ideas (misrepresenting switches, unrelated protocols, or the broader concept of VLAN hopping) but do not specify the tag-double technique that enables crossing VLANs.

Manipulating VLAN tags on Ethernet frames to cross VLAN boundaries relies on how 802.1Q tagging works on trunk links. In the double tagging method, an attacker sends a frame with two VLAN tags: an outer tag that matches the trunk’s native VLAN and an inner tag for the target VLAN. When this frame traverses switches on a trunk, the outer tag is stripped (because it’s seen as the native VLAN), leaving the inner tag to direct the frame into the target VLAN on subsequent switches. This allows traffic to flow into the desired VLAN despite segmentation, effectively bypassing VLAN boundaries. This precise use of two tags is why the approach is described as double tagging. The other options describe different attack ideas (misrepresenting switches, unrelated protocols, or the broader concept of VLAN hopping) but do not specify the tag-double technique that enables crossing VLANs.