This requires two important steps in order for the tool to traverse VLANs for unauthorized access. First, discovery of the correct 12 bit Voice VLAN ID (VVID) used by the IP Phones is required. VoIP Hopper supports multiple protocol discovery methods (CDP, DHCP, LLDP-MED, 802.1q ARP) for this important first step. Second, the tool creates a virtual VoIP ethernet interface on the OS. It then inserts a spoofed 4-byte 802.1q vlan header containing the 12 bit VVID into a spoofed DHCP request.

Once it receives an IP address in the VoIP VLAN subnet, all subsequent ethernet frames are “tagged” with the spoofed 802.1q header.

VoIP Hopper is a VLAN Hop test tool but also a tool to test VoIP infrastructure security.

New Features

• New “Assessment” mode: Interactive, menu driven command interface, improves ability to VLAN Hop in Pentesting when the security tester is working against an unknown network infrastructure
• New VLAN Discovery methods (802.1q ARP, LLDP-MED)
• LLDP-MED spoofing and sniffing support
• Can bypass VoIP VLAN subnets that have DHCP disabled, and spoof the IP address and MAC address of a phone by setting a static IP

You can download VoIP Hopper 2.01 here:

voiphopper-2.01.tar.gz

Or read more here.

VoIP Hopper is a GPLv3 licensed security tool, written in C, that rapidly runs a VLAN Hop into the Voice VLAN on specific Ethernet switches. VoIP Hopper does this by mimicking the behavior of an IP Phone, in both Cisco and Avaya IP Phone environments.

In Cisco IP Phone networks, it first dissects either IEEE 802.3 or Ethernet II for Cisco Discovery Protocol (CDP) packets. If CDP is enabled on the switch port and the Voice VLAN feature is enabled, it will determine the Voice VLAN ID (VVID).

This will allow the tool to create a new Ethernet interface on the PC that tags the 802.1q VLAN header in the Ethernet packet. After VoIP Hopper has created the new Ethernet device, it will send a DHCP client request.

In Avaya IP Phone environments, it sends an Option 55 parameter request list, requesting Option 176. When the DHCP server sends Option 176, it decodes the L2QVLAN reply field for the Voice VLAN ID. It then creates a new voice interface and sends a DHCP request.

Why?

VoIP Hopper was written with the specific aim of improving security in VoIP environments by validating Layer 2 protection controls. It is a VLAN test tool that can be used to validate controls in VoIP environments but also anywhere else VLANs are used (basically everywhere).

You can download VoIP Hopper here:

VoIP Hopper 0.9.7

Or read more here.