VoIP Systems Vulnerable To Attack


Companies eager to tap into the ROI of VoIP are doing so without fully considering the security risks stemming from weaknesses in VoIP applications, operating systems, and structure and supporting services that could spell opportunity for hackers, said David Endler, director of security research at Marlborough, Mass.-based 3Com and its TippingPoint security business.

One of the main weak links in VoIP security is the tendency for organizations to leave phones exposed to the Internet, which enables attackers to use search engines to discover information about the network that they can use in subsequent exploits, according to Endler.

To guard against this threat, companies need to boost the security on VoIP phones by disabling services that aren't needed or restricting access to the specific location, Endler said.

At the Black Hat conference in Las Vegas earlier this month, Endler demonstrated a technique for discovering VoIP phone extensions and user names by sending specially crafted SIP messages to a Cisco VoIP system. Cisco released a subsequent advisory in which it recommended implementing the VoIP infrastructure and data devices on separate VLANs.

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An attacker could use the information to exploit any vendor's SIP-based VoIP infrastructure. "Once you have the extensions, you can perform more advanced attacks," Endler said.

Lance Reid, CEO of NetLogic, Turlock, Calif., said the issue of VoIP security has been somewhat overhyped. "Most of the equipment is behind firewalls and on internal networks that aren't available for public access. As with other internal systems, the only real threat is from people on the inside," Reid said.

However, VoIP security could become a genuine problem for companies down the road, as IP-based unified communication systems are increasingly being designed to interconnect between each other, Reid said.