Voice over IP and IP telephony Network convergence – Telephone and IT – PoE (Power over...
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Transcript of Voice over IP and IP telephony Network convergence – Telephone and IT – PoE (Power over...
![Page 1: Voice over IP and IP telephony Network convergence – Telephone and IT – PoE (Power over Ethernet) Mobility and Roaming Telco – Switched -> Packet (IP)](https://reader030.fdocuments.in/reader030/viewer/2022032722/56649cf05503460f949bf853/html5/thumbnails/1.jpg)
Voice over IP (VoIP) security
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Introduction
• Voice over IP and IP telephony• Network convergence
– Telephone and IT– PoE (Power over Ethernet)
• Mobility and Roaming• Telco
– Switched -> Packet (IP)– Closed world -> Open world
• Security and privacy– IPhreakers – VoIP vs 3G
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Architecture: protocols
• Signaling– User location– Session
• Setup• Negotiation• Modification• Closing• Transport
– Encoding, transport, etc.
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Architecture: protocols
• SIP– IETF - 5060/5061 (TLS) - “HTTP-like, all in one” – Proprietary extensions– Protocol becoming an architecture– “End-to-end” (between IP PBX)
• Inter-AS MPLS VPNs• Transitive trust
– IM extensions (SIMPLE)• H.323
– Protocol family– H.235 (security), Q.931+H.245 (management), RTP, CODECs, etc.– ASN.1
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Architecture: protocols
• RTP (Real Time Protocol)– 5004/udp – RTCP– No QoS/bandwidth management– Packet reordering– CODECs
• old: G.711 (PSTN/POTS - 64Kb/s)• current: G.729 (8Kb/s)
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Architecture: systems
• Systems– SIP Proxy– Call Manager/IP PBX
• User management and reporting (HTTP, etc)– H.323: GK (GateKeeper)– Authentication server (Radius)– Billing servers (CDR/billing)– DNS, TFTP, DHCP servers
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Architecture: systems
• Voice Gateway (IP-PSTN)– Gateway Control Protocols– Signaling: SS7 interface
• Media Gateway Controller– Controls the MG (Megaco/H.248)– SIP interface
• Signaling Gateway– Interface between MGC and SS7– SCTP - ISUP, Q.931
– Transport• Media Gateway: audio conversion
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Architecture: firewall/VPN
• Firewall– “Non-stateful” filtering– “Stateful” filtering– Application layer filtering (ALGs)– NAT / “firewall piercing”
• (H.323 : 2xTCP, 4x dynamic UDP - 1719,1720)• (SIP : 5060/udp)
• Encrypted VPN– SSL/TLS– IPsec – Where to encrypt (LAN-LAN, phone-phone, etc)?
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VOIP Threats
• Denial of Service– ICMP Flood– IP Spoofing – Port Scans – Land Attack– IP Source Route
• Evasdropping or recording– In VOIP eavesdropping is a type of an attack, if an attacker able to eavesdropp a
communication. Then he can launch different type of an attack like Man in the Middle attack etc.
• Call Hijacking and Spoofing• Call Redirection• Voice SPAM (Vishing, Mailbox Stuffing, Unsolicited Calling)• Voicemail Hacking
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VOIP Attacks
• Signaling Layer Attacks– SIP Registration Hijacking– Impersonating a Server– SIP Message Modification– SIP Cancel / SIP BYE attack– SIP DOS attack
• Media Layer Attacks– Eavesdropping– RTP insertion attack
• SSRC collision attacks
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Signaling Layer Attacks
• SIP Registration attack• Attacker impersonates a valid UA to a registrar himself as a valid user
agent. So attacker can recieve calls for a legitmate user.• Impersonating a Server
• When an attacker impersonates a remote server and user agent request are served by the attacker machine.
• SIP Message Modification• If an attacker launches a man in the middle attack and modify a message.
Then attacker could lead the caller to connect to malicious system.• SIP CANCEL / SIP BYE• SIP Denial of Service
• In SIP attacker creates a bogus request that contained a fake IP address and Via field in the SIP header contains the identity of the target host.
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Media Layer Attacks
• Eavesdropping• SSRC collision
• If an attacker eavesdropp the conversation and uses one’s peer SSRC to send RTP packet to other peer, it causes to terminate a session.
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Security Solutions
• Two types of security solutions• End-to-End security
• In SIP end points can ensure end-to-end security to those messages which proxy does not read, like SDP messages could be protectedusing S/MIME.
• Media is transferred directly, so end-to-end security is achieved by SRTP.
• Hop-by-hop security• TLS, IPSec• TLS provide transport layer security over TCP. Normally SIP URI is in
the form of sip:[email protected], but if we are using TLS then SIP URI will be sips:[email protected] and signaling must be send encrypted.
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Authentication
• Authentication means to identify a person.• If we take SIP as signaling protocol in VOIP, it defines two mechanisms
for authentication• HTTP digest authentication• S/MIME
• HTTP Digest Authentication• HTTP digests mechanisms used between users to proxies, users
to users but not between proxies to proxies.• S/MIME
• S/MIME uses X.509 certificates to authenticate end users in the same way that web browsers use them.
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Media Encryption
• In VOIP media is send directly between users using RTP. Encryption of media is achieved by– IPSec– Secure RTP (SRTP)
• It provides a framework for encryption and message authentication of RTP and RTCP.
• Cipher Algorithum: AES• Authenitcation is an optional feature.• SRTP uses Security Description for Media Streams (SDES) algorithum to negotiate
session keys in SDP.
– MIKKEY• Mikkey provides its own authentication and integrity mechanisim.• Mikkey messages carried in a SDP with a=key-mgmt attritbute.
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There are Specialized Hacking Tools
• SIPScan - enumerate SIP interfaces• TFTPBrute - TFTP directory attacking• UDP and RTP Flooder - DoS tools• hping2 – TCP session flooding• Registration Hijacker - tool to take over H.323 session• SIVUS - SIP authentication and registration auditor• Vomit - RTP Playback• VOIP HOPPER – IP Phone mimicing tool• Dsniff - various utilitarian tools (macof and arpspoof)• Wireshark (Ethereal) / tcpdump - packet capture and protocol analysis
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Thanks You