How to Secure VOIP - How to protect against VOIP threats (
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The first step in protecting against such threats is to bolster encryption by
encoding and decoding information securely. Doing so will verify senders'
identities, guarantee that a message's sender can't deny later that the message
was sent, ensure that messages haven't been altered during transmission and
help ensure privacy.
Additionally, a VPN will enable trusted users to securely connect to a VOIP
system from untrusted networks. Internally, a VPN effectively separates the
VOIP network from the underlying data network, sparing the phone system from
any attacks on the rest of the network.
Another good practice is implementing an IPS
(intrusion prevention system). Installed at the network's perimeter, an IPS
scans for known signatures while blocking or allowing traffic based on
application content rather than IP addresses or ports. An IPS
can dynamically modify firewall rules or terminate a network session when
necessary. Many firewall vendors now offer this tool.
It is also a good idea to implement session border controls. Residing on the
network, these control session traffic as it crosses networks or network
segments but allow VOIP to connect to other networks despite obstacles like
firewalls and NAT (Network Address Translation)
devices. This technology protects against SPIT and vishing attacks, and any type
of attack that consists of attackers trying to send malformed packets or call
requests they shouldn't be sending, Lazar said. Vendors offering this
technology include Acme Packet, Covergence, Sipera Systems and BorderWare
Technologies.
Finally, consider a voice-aware firewall, which is optimized by voice,
allowing the opening of ports only when a connection must be established.
Many vendors, such as Sipera, Astaro, Check Point
Software Technologies, Cisco Systems, Crossbeam Systems, Fortinet, Juniper Networks
and SonicWall, now offer combination security tools that include encryption,
firewall, virus scanning, session border control, and intrusion detection and
prevention.
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