A security consultant with expertise in protecting phone conversations as they travel over the internet has unveiled a new tool that demonstrates just how vulnerable voice over internet protocol, or VoIP, calls are to interception.
UCSniff bundles a hodgepodge of previously available open-source applications into a single software package that helps penetration testers assess the security of VoIP calls carried over a client's network. It also introduces several new features that make eavesdropping on specific targets a point-and-click undertaking.
UCSniff runs on a laptop that can be plugged in to the ethernet port of the organization being probed. From there, a VLAN hopper automatically traverses the virtual local area network until it accesses the part that carries VoIP calls. Once the tool has gained unauthorized access, UCSniff automatically injects spoofed ARP, or address resolution protocol, packets into the network, allowing all voice traffic to be routed to the laptop.
UCSniff streamlines eavesdropping by allowing an attacker to zero in on the conversations of particular users. Targets can be selected by extension number or dial-by-name features, making it easy to listen to all calls made by a specific individual - such as an organization's CEO. Eavesdropping can be further fine-tuned by listening only to calls the CEO makes to a specific person - such as a chief financial officer.
"It's silently intercepting all the traffic and forwarding it to the phone, so a regular phone user would not be able to tell the difference," UCSniff creator Jason Ostrom told El Reg. "They think they're talking directly to the other phone when in fact the tool is actually intercepting all the traffic."
UCSniff also makes it easy to capture bi-directional conversations in a single audio file. It automatically records calls that use the G.711 and G.722 codecs.
Yes, the tool requires physical access to an organization's network, and that means remote eavesdropping isn't possible with UCSniff. But for anyone with access to an ethernet port of the company they want to intrude upon, it could prove invaluable. Ostrom says it can be plugged into hotel VoIP systems as well. Contrast this with the difficulty of snooping on traditional phone calls, which typically requires physical access to a private branch exchange.
Ostrom, who is director of research for security firm Sipera Systems, demonstrated UCSniff on Saturday at the Toorcon security conference in San Diego. He plans to release it as a free download in the next few weeks.
Given the ease of snooping on VoIP calls, you'd think organizations would be more diligent about using encryption. Alas, they aren't, says Ostrom, who estimates about 90 per cent of the organizations he tests still haven't figured out the importance of encrypting their calls. Therein lies his motivation for releasing UCSniff.
"I'd like to think that I'm creating this tool to create education awareness," he said. "It's a tool that every security and VoIP owner should have in their bag and that's why we're giving it away for free." ®