ACE (Automated Corporate Enumerator) is a simple yet powerful VoIP Corporate Directory enumeration tool that mimics the behavior of an IP Phone in order to download the name and extension entries that a given phone can display on its screen interface. In the same way that the “corporate directory” feature of VoIP hard phones enables users to easily dial by name via their VoIP handsets.
ACE was developed as a research idea born from “VoIP Hopper” to automate VoIP attacks that can be targeted against names in an enterprise Directory. The concept is that in the future, attacks will be carried out against users based on their name, rather than targeting VoIP traffic against random RTP audio streams or IP addresses. ACE works by using DHCP, TFTP, and HTTP in order to download the VoIP corporate directory. It then outputs the directory to a text file, which can be used as input to other VoIP assessment tools.
ACE currently supports the VoIP corporate directory used in Cisco Unified IP Phones. It works in the following way:
- Spoofs CDP to get VVID
- Adds Voice VLAN Interface (VLAN Hop) – subsequent traffic is tagged with VVID
- Sends DHCP request tagged with VVID
- Decodes TFTP Server IP Address via DHCP Option 150
- Sends a TFTP request for IP Phone configuration file
- Parses file, learning Corporate Directory URL
- Sends an HTTP GET request for Directory
- Parses XML Data, writing directory users to a formatted text file
VoIP (Voice over IP)
Voice over IP (VoIP) is an exciting technology that provides many benefits and cost-effective solutions for communication. It is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks.
More and more small and enterprise businesses are replacing their old traditional telephony systems with IP-based ones. A VoIP-based PBX can provide many features such as Multiple Extensions, Caller ID, Voice mail, IVR capabilities, Recording of conversations, Logging, Usage with hardware-based telephones or software-based (aka softphones). Nowadays there are many vendors for PBX, IP telephones, VoIP services, and equipment such as CISCO, AVAYA, and ASTERISK, SNOM, THOMSON.
With new technology comes a new challenge for both the defensive and offensive sides of security, One of the “great” dangers of traditional phone lines was that it was susceptible to eavesdropping. The “old school” way to eavesdrop on somebody’s phone line was to physically connect a small transmitter that was connected inside or outside their premises somewhere along the phone cord.
ACE-VoIP can be used in one of two ways. First, it can auto-discover the TFTP Server IP Address via DHCP, or (second) the user can specify the TFTP Server IP address as a command line parameter of the tool. In either case, you must supply the MAC Address of the IP Phone with the -m option in order for the tool to correctly download the configuration file via TFTP.
root@kali:~# ace ACE v1.10: Automated Corporate (Data) Enumerator Usage: ace [-i interface] [ -m mac address ] [ -t tftp server ip address | -c cdp mode | -v voice vlan id | -r vlan interface | -d verbose mode ] -i (Mandatory) Interface for sniffing/sending packets -m (Mandatory) MAC address of the victim IP phone -t (Optional) tftp server ip address -c (Optional) 0 CDP sniff mode, 1 CDP spoof mode -v (Optional) Enter the voice vlan ID -r (Optional) Removes the VLAN interface -d (Optional) Verbose | debug mode
Usage requires MAC Address of IP Pone supplied with -m option:
ace -t -m
Mode to automatically discover TFTP server IP via DHCP option 150 (-m):
ace -i eth0 -m 00:15:5d:81:ab:1c
Mode to specify IP Address of TFTP Server:
ace -i eth0 -t 172.17.53.168 -m 00:15:5d:81:ab:1c
Mode to specify the Voice VLAN ID:
ace -i eth0 -v 96 -m 00:15:5d:81:ab:1c
ace -i eth0 -v 96 -m 00:15:5d:81:ab:1c -d
Mode to remove vlan interface:
ace -r eth0.96
Mode to auto-discover voice vlan ID in the listening mode for CDP:
ace -i eth0 -c 0 -m 00:15:5d:81:ab:1c
Mode to auto-discover voice vlan ID in the spoofing mode for CDP:
ace -i eth0 -c 1 -m 00:15:5d:81:ab:1c
Author: Sipera VIPER Lab