VoIP Wars : Return of the SIP
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This document discusses penetration testing of VoIP networks using the Viproy VoIP penetration testing kit. It begins with an introduction of the author and his background in VoIP security. It then demonstrates the Viproy kit in action and discusses basic attacks against SIP services like discovery, footprinting, and spoofing calls. It also covers more advanced attacks like the SIP proxy bounce attack, creating fake services to perform man-in-the-middle attacks, distributed denial of service attacks, and exploiting trust relationships between SIP gateways. The document concludes by discussing fuzzing SIP services and clients to find vulnerabilities.
VoIP Wars : Return of the SIP
- 1. VoIP Wars : Return of the SIP Fatih Özavcı Security Consultant @ Sense of Security (Australia) www.senseofsecurity.com.au @fozavci
- 2. 2 # whois ● Security Consultant @ Sense of Security (Australia) ● 10+ Years Experience in Penetration Testing ● 800+ Penetration Tests, 40+ Focused on NGN/VoIP – SIP/NGN/VoIP Systems Penetration Testing – Mobile Application Penetration Testing – IPTV Penetration Testing – Regular Stuff (Network Inf., Web, SOAP, Exploitation...) ● Author of Viproy VoIP Penetration Testing Kit ● Author of Hacking Trust Relationships Between SIP Gateways ● Blackhat Arsenal USA 2013 – Viproy VoIP Pen-Test Kit ● So, that's me
- 4. 4 # traceroute ● VoIP Networks are Insecure, but Why? ● Basic Attacks – Discovery, Footprinting, Brute Force – Initiating a Call, Spoofing, CDR and Billing Bypass ● SIP Proxy Bounce Attack ● Fake Services and MITM – Fuzzing Servers and Clients, Collecting Credentials ● (Distributed) Denial of Service – Attacking SIP Soft Switches and SIP Clients, SIP Amplification Attack ● Hacking Trust Relationships of SIP Gateways ● Attacking SIP Clients via SIP Trust Relationships ● Fuzzing in Advance ● Out of Scope – RTP Services and Network Tests, Management – Additional Services – XML/JSON Based Soap Services
- 5. 5 # info ● SIP – Session Initiation Protocol – Only Signalling, not for Call Transporting – Extended with Session Discovery Protocol ● NGN – Next Generation Network – Forget TDM and PSTN – SIP, H.248 / Megaco, RTP, MSAN/MGW – Smart Customer Modems & Phones – Easy Management – Security is NOT a Concern?! ● Next Generation! Because We Said So!
- 6. 6 # SIP Services : Internal IP Telephony INTERNET SIP Server Support Servers SIP Clients Factory/Campus SIP over VPN Commercial Gateways Analog/Digital PBX
- 7. 7 # SIP Services : Commercial Services INTERNETSoft Switch (SIP Server) VAS, CDR, DB Servers MSAN/MGW PSTN/ISDN Distributed MPLS 3rd Party Gateways SDP Servers Customers RTP, Proxy Servers Mobile
- 8. 8 # Administrators Think... Root Doesn't! ● Their VoIP Network Isolated – Open Physical Access, Weak VPN or MPLS ● Abusing VoIP Requires Knowledge – With Viproy, That's No Longer The Case! ● Most Attacks are Network Based or Toll Fraud – DOS, DDOS, Attacking Mobile Clients, Spying – Phishing, Surveliance, Abusing VAS Services ● VoIP Devices are Well-Configured – Weak Passwords, Old Software, Vulnerable Protocols
- 9. 9 # Viproy What? ● Viproy is a Vulcan-ish Word that means "Call" ● Viproy VoIP Penetration and Exploitation Kit – Testing Modules for Metasploit, MSF License – Old Techniques, New Approach – SIP Library for New Module Development – Custom Header Support, Authentication Support – New Stuff for Testing: Trust Analyzer, Bounce Scan, Proxy etc ● Modules – Options, Register, Invite, Message – Brute Forcers, Enumerator – SIP Trust Analyzer, Service Scanner – SIP Proxy, Fake Service, DDOS Tester
- 10. 10 # Basic Attacks ● We are looking for... – Finding and Identifying SIP Services and Purposes – Discovering Available Methods and Features – Discovering SIP Software and Vulnerabilities – Identifying Valid Target Numbers, Users, Realm – Unauthenticated Registration (Trunk, VAS, Gateway) – Brute Forcing Valid Accounts and Passwords – Invite Without Registration – Direct Invite from Special Trunk (IP Based) – Invite Spoofing (After or Before Registration, Via Trunk) ● Viproy Pen-Testing Kit Could Automate Discovery
- 11. 11 # Basic Attacks Discovery OPTIONS / REGISTER / INVITE / SUBSCRIBE 100 Trying 200 OK 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error Collecting Information from Response Headers ➔ User-Agent ➔ Server ➔ Realm ➔ Call-ID ➔ Record-Route ➔ ➔ Warning ➔ P-Asserted-Identity ➔ P-Called-Party-ID ➔ P-Preferred-Identity ➔ P-Charging-Vector Soft Switch (SIP Server) Clients Gateways
- 12. 12 # Basic Attacks Register REGISTER / SUBSCRIBE (From, To, Credentials) 200 OK 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error RESPONSE Depends on Informations in REQUEST ➔ Type of Request (REGISTER, SUBSCRIBE) ➔ FROM, TO, Credentials with Realm ➔ Via Actions/Tests Depends on RESPONSE ➔ Brute Force (FROM, TO, Credentials) ➔ Detecting/Enumerating Special TOs, FROMs or Trunks ➔ Detecting/Enumerating Accounts With Weak or Null Passwords ➔ …. Soft Switch (SIP Server) Clients Gateways
- 13. 13 # Basic Attacks ● this isn't the call you're looking for ● We are attacking for... – Free Calling, Call Spoofing – Free VAS Services, Free International Calling – Breaking Call Barriers – Spoofing with... ● Via Field, From Field ● P-Asserted-Identity, P-Called-Party-ID, P-Preferred-Identity ● ISDN Calling Party Number, Remote-Party-ID – Bypass with... ● P-Charging-Vector (Spoofing, Manipulating) ● Re-Invite, Update (Without/With P-Charging-Vector) ● Viproy Pen-Testing Kit Supports Custom Headers
- 14. 14 # Basic Attacks Invite, CDR and Billing Tests Soft Switch (SIP Server) Clients Gateways INVITE/ACK/RE-INVITE/UPDATE (From, To, Credentials, VIA ...) 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error Actions/Tests Depends on RESPONSE ➔ Brute Force (FROM&TO) for VAS and Gateways ➔ Testing Call Limits, Unauthenticated Calls, CDR Management ➔ INVITE Spoofing for Restriction Bypass, Spying, Invoice ➔ …. 100 Trying 183 Session Progress 180 Ringing 200 OK RESPONSE Depends on Informations in INVITE REQUEST ➔ FROM, TO, Credentials with Realm, FROM <>, TO <> ➔ Via, Record-Route ➔ Direct INVITE from Specific IP:PORT (IP Based Trunks)
- 15. 15 # SIP Proxy Bounce Attack ● SIP Proxies Redirect Requests to Other SIP Servers – We Can Access Them via SIP Proxy then We Can Scan – We Can Scan Inaccessible Servers – URI Field is Useful for This Scan ● Viproy Pen-Testing Kit Has a UDP Port Scan Module
- 16. 16 # SIP Proxy Bounce Attack The Wall 192.168.1.145 – Izmir Production SIP Service 192.168.1.146 Ankara White Walker 192.168.1.201 Adana How Can We Use It? ● SIP Trust Relationship Attacks ● Attacking Inaccessible Servers ● Attacking SIP Software – Software Version, Type
- 17. 17 # Fake Services and MITM ● We Need a Fake Service – Adding a Feature to Regular SIP Client – Collecting Credentials – Redirecting Calls – Manipulating CDR or Billing Features – Fuzzing Servers and Clients for Vulnerabilities ● Fake Service Should be Semi-Automated – Communication Sequence Should be Defined – Sending Bogus Request/Result to Client/Server ● Viproy Pen-Testing Kit Has a SIP Proxy and Fake Service ● Fuzzing Support of Fake Service is in Development Stage
- 18. 18 # Fake Services and MITM Usage of Proxy & Fake Server Features Soft Switch (SIP Server) ● Use ARP Spoof & VLAN Hopping & Manual Config ● Collect Credentials, Hashes, Information ● Change Client's Request to Add a Feature (Spoofing etc) ● Change the SDP Features to Redirect Calls ● Add a Proxy Header to Bypass Billing & CDR ● Manipulate Request at Runtime to find BOF Vulnerabilities Clients
- 19. 19 # DOS – It's Not Service, It's Money ● Locking All Customer Phones and Services for Blackmail ● Denial of Service Vulnerabilities of SIP Services – Many Responses for Bogus Requests → DDOS – Concurrent Registered User/Call Limits – Voice Message Box, CDR, VAS based DOS Attacks – Bye And Cancel Tests for Call Drop – Locking All Accounts if Account Locking is Active for Multiple Fails ● Multiple Invite (After or Before Registration, Via Trunk) – Calling All Numbers at Same Time – Overloading SIP Server's Call Limits – Calling Expensive Gateways,Targets or VAS From Customers ● Viproy Pen-Testing Kit Has a few DOS Features
- 20. 20 # DDOS – All Your SIP Gateways Belong to Us ! ● SIP Amplification Attack + SIP Servers Send Errors Many Times (10+) + We Can Send IP Spoofed Packets + SIP Servers Send Responses to Victim => 1 packet for 10+ Packets, ICMP Errors (Bonus) ● Viproy Pen-Testing Kit Has a PoC DDOS Module ● Can we use SIP Server's Trust ? -wait for it-
- 21. 21 # DDOS – All Your SIP Gateways Belong to Us! The Wall 192.168.1.201 – Izmir Production SIP Service 192.168.1.202 – Ankara Production SIP Service Citadel IP Spoofed Call Request White Walker The Wall 192.168.1.203 – Adana Production SIP Service
- 22. 22 # Hacking SIP Trust Relationships ● NGN SIP Services Trust Each Other – Authentication and TCP are Slow, They Need Speed – IP and Port Based Trust are Most Effective Way ● What We Need – Target Number to Call (Cell Phone if Service is Public) – Tech Magazine, Web Site Information, News ● Baby Steps – Finding Trusted SIP Networks (Mostly B Class) – Sending IP Spoofed Requests from Each IP:Port – Each Call Should Contain IP:Port in "From" Section – If We Have a Call, We Have The Trusted SIP Gateway IP and Port – Brace Yourselves The Call is Coming
- 23. 23 The Wall # Hacking SIP Trust Relationships Slow Motion 192.168.1.201 – Izmir Production SIP Service Ankara Istanbul International Trusted Operator IP Spoofed Call Request Contains IP:Port Data in From White Walker
- 24. 24 # Hacking SIP Trust Relationships Brace Yourselves, The Call is Coming 192.168.1.201 – Izmir Production SIP Service White Walker Ankara Istanbul International Trusted Operator IP Spoofed Call Request Somebody Known in From Come Again? ● Billing ? ● CDR ? ● Log ? From Citadel The Wall
- 25. 25 # Hacking SIP Trust Relationships – Business Impact ● Denial of Service – Short Message Service and Billing – Calling All Numbers at Same Time – Overloading SIP Server's Call Limits – Overloading VAS Service or International Limits – Overloading CDR Records with Spoofed Calls ● Attacking a Server Software – Crashing/Exploiting Inaccesible Features – Call Redirection (working on it, not yet :/) ● Attacking a Client? – Next Slide!
- 26. 26 # Attacking a Client via SIP Trust Relationships ● SIP Server Redirects a few Fields to Client – FROM, FROM NAME, Contact – Other Fields Depend on Server (SDP, MIME etc) ● Clients Have Buffer Overflow in FROM? – Send 2000 Chars to Test it ! – Crash it or Execute your Command if Available ● Clients Trust SIP Servers and Trust is UDP Based – This module can be used for Trust Between Client and Server ● Viproy Pen-Testing Kit SIP Trust Module – Simple Fuzz Support (FROM=FUZZ 2000) – You Can Modify it for Further Attacks
- 27. 27 # Attacking a Client via SIP Trust Relationships Brace Yourselves 550 Chars are Coming 192.168.1.201 – Izmir Production SIP Service White Walker Ankara Istanbul International Trusted Operator IP Spoofed Call Request 550 Chars in From CRASSSSH! ● Command? ● Why Not! Bogus Invite Request The Wall The Wall AdorePhone Iphone App
- 28. 28 # Fuzz Me Maybe ● Fuzzing as a SIP Client | SIP Server | Proxy | MITM ● SIP Server Software ● SIP Clients – Hardware Devices, IP Phones, Video Conference Systems – Desktop Application or Web Based Software – Mobile Software ● Special SIP Devices/Software – SIP Firewalls, ACL Devices, Proxies – Connected SIP Trunks, 3rd Party Gateways – MSAN/MGW – Logging Software (Indirect) – Special Products: Cisco, Alcatel, Avaya, Huawei, ZTE...
- 29. 29 # Old School Fuzzing ● Request Fuzzing – SDP Features – MIME Type Fuzzing ● Response Fuzzing – Authentication, Bogus Messages, Redirection ● Static vs Stateful ● How about Smart Fuzzing – Missing State Features (ACK,PHRACK,RE-INVITE,UPDATE) – Fuzzing After Authentication (Double Account, Self-Call) – Response Fuzzing (Before or After Authentication) – Missing SIP Features (IP Spoofing for SIP Trunks, Proxy Headers) – Numeric Fuzzing for Services is NOT Memory Corruption – Dial Plan Fuzzing, VAS Fuzzing
- 30. 30 # How Viproy Pen-Testing Kit Helps Fuzzing Tests ● Skeleton for Feature Fuzzing, NOT Only SIP Protocol ● Multiple SIP Service Initiation – Call Fuzzing in Many States, Response Fuzzing ● Integration With Other Metasploit Features – Fuzzers, Encoding Support, Auxiliaries, Immortality etc. ● Custom Header Support – Future Compliance, Vendor Specific Extensions, VAS ● Raw Data Send Support (Useful with External Static Tools) ● Authentication Support – Authentication Fuzzing, Custom Fuzzing with Authentication ● Less Code, Custom Fuzzing, State Checks ● Some Features (Fuzz Library, SDP) are Coming Soon
- 31. 31 # Fuzzing SIP Services Request Based OPTIONS/REGISTER/SUBSCRIBE/INVITE/ACK/RE-INVITE/UPDATE.... Soft Switch (SIP Server) Gateways 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error Fuzzing Targets, REQUEST Fields ➔ Request Type, Protocol, Description ➔ Via, Branch, Call-ID, From, To, Cseq, Contact, Record-Route ➔ Proxy Headers, P-*-* (P-Asserted-Identity, P-Charging-Vector...) ➔ Authentication in Various Requests (User, Pass, Realm, Nonce) ➔ Content-Type, Content-Lenth ➔ SDP Information Fields ➔ ISUP Fields 100 Trying 183 Session Progress 180 Ringing 200 OK Clients
- 32. 32 # Fuzzing SIP Services Response Based OPTIONS Soft Switch (SIP Server) Gateways INVITE/ACK 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error 100 Trying 183 Session Progress 180 Ringing 200 OK INVITE Myself / INVITE I'm Proxy MALICOUS RESPONSE MALICOUS RESPONSE Potential RESPONSE Types for Fuzzing Clients
- 33. SIP Bounce Attack, Hacking SIP Trust, Attacking Mobile Apps http://www.youtube.com/watch?v=bSg3tAkh5gA
- 34. 34 References ● Viproy VoIP Penetration and Exploitation Kit Author : http://viproy.com/fozavci Homepage : http://viproy.com/voipkit Github : http://www.github.com/fozavci/viproy-voipkit ● Attacking SIP Servers Using Viproy VoIP Kit (50 mins) https://www.youtube.com/watch?v=AbXh_L0-Y5A ● Hacking Trust Relationships Between SIP Gateways (PDF) http://viproy.com/files/siptrust.pdf ● VoIP Pen-Test Environment – VulnVoIP http://www.rebootuser.com/?cat=371
- 35. 35 Special Thanks to... Special Ones ● Konca Ozavci ● Kadir Altan ● Anil Pazvant Suggestions & Guidelines & Support ● Paul Henry ● Mark Collier ● Jason Olstrom ● Jesus Perez Rubio
- 36. Q ?
- 37. Thanks