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VoIP Security (Voice over Internet Protocol)

VoIP Security (Voice over Internet Protocol)

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VoIP Security (Voice over Internet Protocol)

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  1. VoIP Security(Voice over Internet Protocol) Brian Martin Matt Protacio February 28, 2007

  2. History of VoIP • First “internet phone” service offered in 1995 by a company called Vocaltec • Most people didn’t yet have broadband, and most soundcards were half duplex. • First PC to phone service in 1998, followed by phone to phone service. Cisco, Nortel, and Lucent develop hardware VOIP switches (gateways). • VOIP traffic exceeded 3% of voice traffic by 2000

  3. History of VoIP (Continued) • Around 2004 began mass marketing for “digital phone” service bundled with broadband arranged so calls would be received over regular phones. • “Digital phone” services use an adaptor from the modem to a phone jack so there is almost no difference between that and regular phone service. Other services use software clients requiring a computer with a microphone.

  4. VoIP vs. Old Phones • Benefits: • More efficient bandwidth usage • Only one type of network required, data abstraction in the network • Criticisms: • 911 localization doesn’t always work • Phones aren’t useable in a power outage, unless UPS are deployed • Fax machines might not work

  5. Common VoIP Security Threats • VoIP Security Alliance, founded in 2005 • Threat Taxonomy • Forums, Articles • Caller misrepresentation, caller id spoofing • Unwanted calls, spam or stalking

  6. Common VoIP Security Threats (Continued) • Traffic Capture • Eavesdropping • Interception • Alteration (conversion quality, content) • Black holing • Call Hijacking • SIP (Session Initiation Protocol) register hijacking • DoS

  7. SIP registration hijacking with SiVuS and a botnet • SIP • Session Initiation Protocol • Application layer control protocol for initiating VOIP sessions • Control messages were not encrypted and had no mechanism to verify integrity • So even if registration requires authentication, it can be sniffed easily

  8. The basic attack plan • Both Callers must register with a registrar server before a call may be initiated • DoS the receiver with zombie minions • Deregister him with the registrar • Falsify his registration with SiVuS • Anyone planning to call him will not know and you can try to claim you are the legitimate call receiver. • Chances are the intended call receiver will not notice either

  9. Good Ideas • If using SIP use TLS • Transport Layer Security (encryption, basically) • The text based messages of SIP are considered a feature though • If only VoIP appliances are connected to the the network, then no PCs are available to launch attacks from. • Segregate data and voice to their own Virtual Lans (VLANs) • Encrypt!!! • Prevents voice injections and casual eavesdropping • Redundant network to deal with DoS. • Secure IP-PBX and gateway boxes

  10. VoIP Popularity • “VoIP use has more than doubled in the past year, according to Telegeography Research, and experts expect the growth to continue.” • New York Daily News, Februray 26, 2007

  11. Popular VoIP Services • Enterprise • Cisco CallManager • Home • Vonage • Skype • Cable Companies (Time Warner, Insight, Comcast, etc.)

  12. Cisco CallManager • Enterprise VoIP Product • Marketed towards companies and organizations looking to replace legacy PBX (Private Business Exchange) systems or install a new IP telephony based system

  13. Cisco CallManager System Design • Phones • Deskphones, model 7960 • Ethernet, PoE (Power over Ethernet) • Software Phone • IP Communicator • Popular for using across a VPN

  14. Software Phone: IP Communicator

  15. Cisco CallManager System Design (continued) • Servers • CallManager Subscribers and Publishers • Windows or Linux Servers running Cisco Software • Process all calls • Interface with existing PBX systems

  16. CallManager Security • Multiple VLANs • Separate VLANs for Voice and Data • Higher Security by isolating voice on separate VLAN • Primary Protocols • SIP • H.323

  17. H.323 Attack • Attacker can exploit the open standard protocol to establish malicious phone calls • Microsoft Netmeeting can be used to initiate an H.323 Phone Call • Malicous phone calls can be established to make international calls • Threat can be eliminated by not allowing international dialing on lines from telephone company

  18. IP Phone Tap • Capture IP packets from Phone • Use Ethereal network sniffer • Extract audio from packets • Export audio file of phone call

  19. Prevent Phone Tapping • Encrypt voice traffic • Prevent attacker from capturing traffic out of a phone • Lock down access to network switch phone is connected to

  20. Conclusion • VoIP is established as the future of telephones • Security is critical when designing and maintaining VoIP systems Questions?