© Verizon Copyright 2009. June 23, 2015 Columbia - Verizon Research Secure SIP: Scalable DoS Prevention Mechanisms for SIP- based VoIP Systems, and Validation.

© Verizon Copyright 2009. June 23, 2015 Columbia - Verizon Research Secure SIP: Scalable DoS Prevention Mechanisms for SIP- based VoIP Systems, and Validation Test Tools Gaston Ormazabal Verizon Laboratories

© Verizon Copyright 2009. 22 Agenda A successful collaboration –Verizon and CATT Professor Schulzrinne - three year program Project Overview –Background, Research Focus, and Goals –DoS VoIP Threat Model DoS Detection and Mitigation Strategy DoS Validation Methodology - DoS Automated Attack Tool Value to Verizon –Intellectual Property/Technology Licensing Next Steps Conclusions

© Verizon Copyright 2009. 3 Verizon – CATT Program Collaboration between Verizon and Center of Advanced Technology Telecommunications Verizon PI: Gaston Ormazabal CATT –Columbia University PI: Prof. Henning Schulzrinne Graduate Students –Currently Milind Nimesh –Previously Sarvesh Nagpal, Eilon Yardeni –New York University Polytechnic Institute

© Verizon Copyright 2009. 44 Background & Research Focus SIP is the VoIP protocol of choice for both wireline and wireless telephony –Control protocol for the Internet Multimedia Systems (IMS) architecture VoIP services fast becoming attractive DoS and ToS targets –DoS attack traffic traversing network perimeter reduces availability of signaling and media for VoIP –Theft of Service must be prevented to maintain service integrity –Reduces ability to collect revenue and provider’s reputation both are at stake Attack targets –SIP infrastructure elements (proxy, softswitch, SBC, CSCF-P/I/S) –End-points (SIP phones) –Supporting services (e.g., DNS, Directory, DHCP, HSS, DIAMETER, Authorization Servers) Verizon needs to solve security problem for VoIP services –Protocol-aware application layer gateway for RTP –SIP DoS/DDoS detection and prevention for SIP channel –Theft of Service Architectural Integrity Verification Tool Need to verify performance & scalability at carrier class rates –Security and Performance are a zero sum game Columbia likes to work on real life problems & analyze large data sets –Goal of improving generic architectures and testing methodologies –Columbia has world-renowned expertise in SIP

© Verizon Copyright 2009. 55 Goals Study VoIP DoS and ToS for SIP –Definition – define SIP specific threats –Detection – how do we detect an attack? –Mitigation – defense strategy and implementation –Validation – validate our defense strategy Generate requirements for future security network elements and prototypes –Share these requirements with vendors Generate the test tools and strategies for their validation –Share these tools with vendors

© Verizon Copyright 2009. 77 VoIP Threat Taxonomy Scope of our research - 2006 Scope of our research - 2007 *- VoIP Security and Privacy Threat Taxonomy, VoIP Security Alliance Report, October, 2005 (http://www.voipsa.org)http://www.voipsa.org

© Verizon Copyright 2009. 88 Denial of Service & Theft of Service Denial of Service – preventing users from effectively using the target services –Service degradation to a “not usable” point –Complete loss of service Distributed Denial of Service attacks represent the main threat facing network operators* –Most attacks involve compromised hosts (bots) botnets sized from a few thousands to over a million 25% of all computers on Internet may be botnets Theft of Service – any unlawful taking of an economic benefit from a service provider – With intention to deprive of lawful revenue or property *- Worldwide ISP Security Report, September 2005, Arbor Networks *- Criminals 'may overwhelm the web', 25 January, 2007. BBC

© Verizon Copyright 2009. 10 DoS Implementation Flaws Vulnerability target origin –Different levels of the network protocol stack –Underlying OS/firmware Result –Excessive consumption Memory Disk CPU –System reboot or crash –Potential for TOS Attacker sends carefully crafted packet(s) to exploit a specific implementation flaw

© Verizon Copyright 2009. 11 DoS Application Level Attacks Registration Hijacking –Attacker registers his device with another user's URI Call Hijacking –Attacker injects a “301 Moved Permanently” message to an active session Amplification attacks –Attacker creates bogus requests with falsified Via header field that identifies a target host UAs/proxies generate a DDoS against that target A feature of SIP is manipulated to cause a DoS attack

© Verizon Copyright 2009. 12 DoS Application Level Attacks Session teardown attacks –Attacker spoofs a BYE message Injects it to an active session Tears down the session Tricks billing server to stop billing, call continues Modification of media sessions –Attacker spoofs re-INVITE messages causing QoS reduction Media redirection Security attributes modification Media streams attacks –Attacker injects spoofed RTP packets with high SEQ numbers into the media streams Changes the play-out sequence

© Verizon Copyright 2009. 13 DoS Flooding Attacks IP variants –UDP floods –ICMP echo attacks –SYN floods VoIP variants –Floods of INVITE or REGISTER messages Cause excessive processing at a SIP proxy –Floods of RTP Cause excessive processing at Media Gateway Requires more resources from the attacker Harder to defend against –Even the best maintained networks can become congested Attacker floods a network link or overwhelms the target host

© Verizon Copyright 2009. 15 Mitigation Strategy Implementation flaws are easier to deal with –Systems can be tested before used in production –Systems can be patched when a new flaw is discovered –Attack signatures can be integrated with a firewall Application level and flooding attacks are harder to defend against –SIP infrastructure element defense Commercially available solutions for general UDP/SYN flooding but none for SIP  Address application level and flooding attacks specifically for SIP

© Verizon Copyright 2009. 16 Strategy Focus VULNERABILITY : Most security problems are due to: –flexible grammar  syntax-based attacks –Plain text  interception and modification –SIP over UDP  ability to spoof SIP requests Registration/Call Hijacking Modification of Media sessions SIP ‘Method’ vulnerabilities –Session teardown –Request flooding –Error Message flooding RTP flooding STRATEGY: Two DoS detection and mitigation filters –SIP: Two types of rule-based detection and mitigation filters –Media: SIP-aware dynamic pinhole filtering Application Level Flooding

© Verizon Copyright 2009. 17 Previous Work on SIP DoS Implemented a large scale SIP-aware firewall using dynamic pinhole filtering –First-line of defense against DoS attacks at the network perimeter Only signaled RTP media channels can traverse it End systems are protected against flooding of random RTP The RTP pinhole filtering approach is a good first-line of defense but… –The signaling port (5060) is still subject to attack on the signaling infrastructure –  hence SIP specific filtering was implemented for the first time

© Verizon Copyright 2009. 19 SIP Detection and Mitigation Filters Authentication Based - Return Routability Check –Require SIP built-in digest authentication mechanism Authentication with shared secret –Filter out spoofed sources Method Specific Based – Rate Limiting –Transaction based Thresholding of message rates –INVITE –Errors State Machine sequencing –Filter “out-of-state” messages –Allow “in-state” messages –Dialog based Only useful in BYE and CANCEL messages Dynamic Pinhole Filtering for RTP Only signaled RTP media channels can traverse perimeter –Obtain from SDP interception End systems are protected against flooding of random RTP

© Verizon Copyright 2009. 20 CloudShield CS-2000 System 10/100/100010/100 E1E1 E2E2 Backplane F0F0 C3C3 C4C4 Gigabit Ethernet Interconnects D0D0 D1D1 E1E1 E2E2 F0F0 C3C3 C4C4 D0D0 D1D1 3 4 P0P0 P0P0 System Level Port Distribution Application Server Module Pentium 1GHz 1000 012 ASM DPPM Intel IXP 2800 DPPM Intel IXP 2800

© Verizon Copyright 2009. 21 SIP Digest Authentication User Agent Client (UAC) Proxy Server INVITE Generate the nonce value 407 Proxy Authentication Required (nonce, realm..) INVITE (nonce, response…) Authentication: compute F(nonce, username, password, realm) and compare with response ACK Compute response = F(nonce, username, password, realm) nonce – a uniquely generated string used for one challenge only and has a life time of 60 seconds

© Verizon Copyright 2009. 22 SIP Digest Authentication Statistics Digest authentication accounts for –nearly 80% of processing cost of a call for a stateless server –45% of a call for a stateful server* Additional cost –70% for message processing –30% for authentication computation (hashing)* * SIP Security Issues: The SIP Authentication Procedure and its Processing Load, Salsano et al., IEEE Network, November 2002

© Verizon Copyright 2009. 23 NPU DPPM RAM Return-Routability Implementation Succeeds SIP UA sipd INVITE407 Needs Auth IP 128.59.21.70 CAM (128.59.21.70, nonce="6ydARDP51P8Ef9H4iiHmUc7iFDE=" ) UntrustedTrusted INVITE, Proxy-Auth Remove Filter (128.59.21.70, ”nonce”) INVITE INVITE sip:test1@cs.columbia.edu SIP/2.0 Via: SIP/2.0/UDP 128.59.21.70:5060 Max-Forwards: 70 From: sip:test5@cs.columbia.edu To: sip:test1@cs.columbia.edu Contact: sip:test5@128.59.21.70:5060 Subject: sipstone invite test CSeq: 1 INVITE Call-ID: 1736374800@lagrange.cs.columbia.edu Content-Type: application/sdp Content-Length: 211 v=0 o=user1 53655765 23587637 IN IP4 128.59.21.70 s=Mbone Audio t=3149328700 0 i=Discussion of Mbone Engineering Issues e=mbone@somewhere.com c=IN IP4 128.59.21.70 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 Add Filter (128.59.21.70, ”nonce”) 407 Needs Auth SIP/2.0 407 Proxy Authentication Required Via: SIP/2.0/UDP 127.0.0.1:7898 From: sip:test5@cs.columbia.edu To: sip:test1@cs.columbia.edu; tag=2cg7XX0dZQvUIlbUkFYWGA Call-ID: 1736374800@lagrange.cs.columbia.edu CSeq: 1 INVITE Date: Fri, 14 Apr 2006 22:51:33 GMT Server: Columbia-SIP-Server/1.24 Content-Length: 0 Proxy-Authenticate: Digest realm="cs.columbia.edu", nonce="6ydARDP51P8Ef9H4iiHmUc7iFDE=", stale=FALSE, algorithm=MD5, qop="auth,auth-int" INVITE sip:test1@cs.columbia.edu SIP/2.0 Via: SIP/2.0/UDP 128.59.21.70:5060 Max-Forwards: 70 From: sip:test5@cs.columbia.edu To: sip:test1@cs.columbia.edu Contact: sip:test5@128.59.21.70:5060 Subject: sipstone invite test CSeq: 3 INVITE Call-ID: 1736374800@lagrange.cs.columbia.edu Content-Type: application/sdp Content-Length: 211 Proxy-Authorization: Digest username="anonymous", realm="cs.columbia.edu", nonce="6ydARDP51P8Ef9H4iiHmUc7iFDE=", uri="sip:test1@cs.columbia.edu", response="0480240000edd6c0b64befc19479924c", opaque="", algorithm="MD5" v=0 o=user1 53655765 2353687637 IN IP4 128.59.21.70 s=Mbone Audio t=3149328700 0 i=Discussion of Mbone Engineering Issues e=mbone@somewhere.com c=IN IP4 128.59.21.70 t=0 0 m=audio 3456 RTP/AVP 0 a=rtpmap:0 PCMU/8000 INVITE, Proxy-Authorization

© Verizon Copyright 2009. 24 Return-Routability Implementation Fails SIP UA NPU DPPMsipd INVITE 407 Needs Auth IP 1.2.3.4 CAM Add Filter (1.2.3.4,”nonce”) INVITE X UntrustedTrusted (1.2.3.4, nonce="6ydARDP51P8Ef9H4iiHmUc7iFDE=" ) RAM

© Verizon Copyright 2009. 25 SIP Session Analysis A call contains one or more Dialogs –A Dialog contains one or more Transactions Request/response Typically 2 in case of an INVITE-200 OK & BYE-OK type of session –Transactions are of two types Client –INVITE Transactions –Non-INVITE Transactions Server –INVITE Transactions –Non-INVITE Transactions SIP sessions/calls can be broken down to 4 levels of granularity

© Verizon Copyright 2009. 27 Level Identifiers Dialog Level –A Dialog is identified by The “Call-ID” field The “From” Tag The “To” Tag –Rate-limiting at Dialog level is coarser  not applied to keep state information Transaction Level –A Transaction is identified by The "Branch" parameter of the Via header The "Method" name in the CSeq field –Rate-limiting is more refined and can pinpoint to more specific parameter thresholds  more effective to keep state information The Transaction-ID and Dialog-ID are generated by applying CRC-32 on a collection of the above mentioned fields. –The unique CRC-32 Hash generated is used as an index in the CAM tables

© Verizon Copyright 2009. 28 Method Specific Filtering INVITE –Filter redundant INVITE messages by looking up its Transaction-ID and rejecting if its Transaction-ID already exists in State tables. Responses –100 Trying –180 Ringing –200 OK –Errors (300 – 600) Out-of-State –Sequence of unexpected messages This approach involves defense against specific method vulnerabilities

© Verizon Copyright 2009. 29 Transaction Filtering Rate limit messages based on expected Transaction traffic: –1 INVITE per transaction –1 (or more) 100 Trying per transaction –1 (or more) 180 Ringing per transaction –1 200OK per transaction –1 ACK per transaction –N (based on testing) errors per transaction Error status message rate limiter implemented as high- speed counters in SRAM with granularity of 1 second Rate limits error status messages within the context of a valid transaction

© Verizon Copyright 2009. 30 SIP Message Relationships CAM database has very low latency lookups Aged lookup tables implemented to track dialog and transaction relationships –Message lookup tables Dialog-ID Table Transaction-ID Table –Messages Identified by Type and Code Type: Request or Response Code: Request Method or Response Status Code Dialog ID Transaction ID

© Verizon Copyright 2009. 31 Transaction Filtering For every new SIP request message received, a Transaction-ID (TXNID) is created –TXNID is a 32 bit integer calculated by HASH (Top Via: BranchID, CSEQ Command Value) TXNIDs are stored in a different CAM table (from pinholes and nonces) –If TXNID is duplicate, drop the packet “Ideally” only one SIP request message allowed per TXNID –Binary switch Retransmission of same request multiple times require a finite retransmissions window –5 packets in current network set up –Should be settable for more complex networks –Optimization to reduce false positives –If TXNID is not duplicate, then go on to next step When new subsequent status messages are received: –If status message record is valid, request accepted –If status message record is bogus, packet dropped Additional check rate of requests per transaction per second not to exceed a selected finite number (6), else packet dropped

© Verizon Copyright 2009. 32 SIP Transaction State Validation Makes an entry for first Transaction Request and logs subsequent status messages –Logs all messages on per transaction basis –Use of wild cards in regular expression syntax –All permutations of allowed states validated in a single operation Received packet is added to status messages table for original Transaction –If received status message fits valid state pattern, it is accepted –Messages resulting in invalid state pattern are dropped and also removed from transaction message log e.g.: the sequence INVITE, 100, 180, 200, 180, 200 causes filter to only allow INVITE, 100, 180, 200, and 180/200 is struck out as 180 is out of state –Transaction state is rolled back to the last known good state Overlays on top of other filtering mechanisms

© Verizon Copyright 2009. 34 Firewall Components Static Filtering –Filtering of pre-defined ports (e.g., SIP, ssh, 6252) Dynamic Filtering –Filtering of dynamically opened RTP ports –Filtering of nonce and method redundancy Switching Layer –Perform switching between the input ports Firewall Control Module –Intercept SIP call setup messages –Get nonce from 407 Need Auth –Get RTP ports from the SDP –Maintain call state Firewall Control Protocol –The way the Firewall Control Module talks with the firewall –Push filter for SIP UA authentication challenge (with nonce) and media ports –Push dynamic table updates to the data plane –May be used by multiple SIP Proxies that control one or more firewalls Firewall Data Plane Execution Part of SIP-proxy Executed in the Linux Control Plane

© Verizon Copyright 2009. 38 Integrated Testing and Analysis Environment GigE Switch SIP Proxy Call Handlers SIPUA/SIPp Controller secureSIP Attack Loaders SIPStone/SIPp Legitimate Loaders SIPUA/SIPp Firewall

© Verizon Copyright 2009. 39 Test Tools SIPp, SIPStone, and SIPUA are benchmarking tools for SIP proxy and redirect servers –Establish calls using SIP in Loader/Handler mode –A controller software module (secureSIP) wrapped over SIPp/SIPUA/SIPStone launches legitimate and illegitimate calls at a pre-configured workload SIPp –Robust open-source test tool / traffic generator for SIP –Customizable XML scenarios for traffic generation –5 inbuilt timers to provide accurate statistics –Customized to launch SIP DoS attack traffic scenarios designed to cause proxy to fail SIPStone –Continuously launches spoofed calls which the proxy is expected to filter –For this project enhanced with: –Null Digest Authentication –Optional spoofed source IP address SIP requests SIPUA Test Suite –Built-in Digest Authentication functionality –Sends 160 byte RTP packets every 20ms –Settable to shorter interval (10ms) if needed for granularity –Starts RTP sequence numbers from zero –Dumps call number, sequence number, current timestamp and port numbers to a file

© Verizon Copyright 2009. 40 secureSIP Controller Controller –Automated Web-based Control Software run on SUN (Linux) box –Connects to the Pair of End Points (Loaders and Handlers) Supplies external traffic generation over Private Channel (6252) –Launches attack traffic Changes type of traffic on the fly External stress on SUT –SIPp in Array Form supplies traffic from 16 SUN (Linux) boxes in various configurations for SIP DoS experiments –SIPUA in Array Form supplies traffic from 16 SUN (Linux) boxes for pinhole experiments Results Analyzer –Gathers, analyzes and correlates results Handler/Loaders update results to database in real-time Controller analyzes results from databases and aggregates them to get the number of initiated and torn-down calls and their rates

© Verizon Copyright 2009. 42 secureSIP Test Results for DoS & Pinholes Firewall Filters OFFFirewall Filters ON Traffic Composition Good CPS Attack CPS CPU Load Good CPS Attack CPS CPU Load Non-Auth Traffic 690087.81690088.04 Auth Good Traffic 240019.83240039.64 480081.20480081.75 Auth Good Traffic + Spoof Traffic 240295083.642401680041.39 48019585.404801440082.72 Auth Good Traffic + Flood of Requests 240323084.42240840040.83 48057086.12480720082.58 Auth Good Traffic + Flood of Responses 240297087.2240840041.33 48033086.97480720082.58 Auth Good Traffic + Flood of Out-of- State 240280586.24240840040.29 48029084.81480720082.19 Concurrent Calls Call rate (CPS) Delay due to Firewall Pinhole opening ms Pinhole closing ms 2000030014.60 25000300150 3000030016.6155.1 30000200160.2 SIP DoS Measurements (showing max supported call rates) Dynamic Pinhole

© Verizon Copyright 2009. 43 The Bigger Picture - Columbia VoIP Testbed Columbia VoIP test bed is collection of various open-source, commercial and home-grown SIP components –provides a unique platform for validating research Columbia-Verizon Research partnership has addressed major security problems –signalling, media and social threats Researched DoS solutions verified against powerful test setup at very high traffic rates ToS successfully validated integrity of different setups of test bed

© Verizon Copyright 2009. 44 Value to Verizon Enhanced VoIP security via standards and vendor involvement –Columbia requirements valid for VoIP, Presence and Multimedia architectures –Rolled the requirements and lessons learned into the Verizon security architecture and new element requirements database for procurement –Working with Verizon vendors to mitigate exposures Setup “one-of-its-kind” laboratory facilities for VoIP security evaluations and product development –At Columbia, prototype rapid development incubator –At Verizon, Columbia/Verizon collaborative test tools set up for a more realistic complex IP-routed laboratory environment Intellectual Property with Six Patent Applications –Taken research quickly into marketplace with rapid commercialization –Licensing Agreement with equipment manufacturers Several vendors interested Exclusive vs. Non-exclusive –Verizon Intellectual Property contact: Gwen Thaxter (gwen.thaxter@verizon.com, 845-620-5156)gwen.thaxter@verizon.com

© Verizon Copyright 2009. 45 Intellectual Property - Patent Applications “Fine Granularity Scalability and Performance of SIP Aware Border Gateways: Methodology and Architecture for Measurements” –Inventors: Henning Schulzrinne, Kundan Singh, Eilon Yardeni (Columbia), Gaston Ormazabal (Verizon) “Architectural Design of a High Performance SIP-aware Application Layer Gateway” –Inventors: Henning Schulzrinne, Jonathan Lennox, Eilon Yardeni (Columbia), Gaston Ormazabal (Verizon) “Architectural Design of a High Performance SIP-aware DOS Detection and Mitigation System” –Inventors: Henning Schulzrinne, Eilon Yardeni, Somdutt Patnaik (Columbia), Gaston Ormazabal (Verizon) “Architectural Design of a High Performance SIP-aware DOS Detection and Mitigation System - Rate Limiting Thresholds” –Inventors: Henning Schulzrinne, Somdutt Patnaik (Columbia), Gaston Ormazabal (Verizon) “System and Method for Testing Network Firewall for Denial of Service (DoS) Detection and Prevention in Signaling Channel” –Inventors: Henning Schulzrinne, Eilon Yardeni, Sarvesh Nagpal (Columbia), Gaston Ormazabal (Verizon) “Theft of Service Architectural Integrity Validation Tools for Session Initiation Protocol (SIP) Based Systems” –Inventors: Henning Schulzrinne, Sarvesh Nagpal (Columbia), Gaston Ormazabal (Verizon)

© Verizon Copyright 2009. 46 Publications, Presentations, Recognition Importance of rapid dissemination of results in industry and academia –For knowledge diffusion and ubiquity among research practitioners –For PR reasons (licensing agreements and potential sales) Presentation at NANOG 38 – Oct. 10 2006 (HS/GO) –Paper published in NANOG 38 2006 Proceedings - “Scalable Mechanisms for Protecting SIP- Based VoIP Systems” –Made a headline in VON Magazine on October 11, 2006: http://www.vonmag.com/webexclusives/2006/10/10_NANOG_Talks_Securing_SIP.asp http://www.vonmag.com/webexclusives/2006/10/10_NANOG_Talks_Securing_SIP.asp Presentation to at Global 3G Evolution Forum – Tokyo, Japan, Jan. 2007 (GO) Presentation/demo at IPTComm 2007 – New York City, July, 2007 (GO) Presentation at OSS/BSS Summit – Tucson, AZ, September, 2007 (GO) Presentation at Columbia Science and Technology Ventures Symposium: “From Signal to Information Displayed in a Wireless World”, April 2008 (HS/GO) Presentation at IPTComm 2008 – Heidelberg, July, 2008 “Secure SIP: A scalable prevention mechanism for DoS attacks on SIP based VoIP systems” (GO) Presentation at IIT VoIP Conference and Expo IV – Chicago, October, 2008 (GO) Paper published by Springer Verlag - “Principles, Systems and Applications of IP Telecommunications” in October 2008: http://www.springerlink.com/content/r5t1652v3572/ http://www.springerlink.com/content/r5t1652v3572/ Work incorporated in a new Masters level course on VoIP Security taught at Columbia since Fall 2006, every year –COMS 4995-1: Special Topics in Computer Science : VoIP Security (HS) CATT Technological Impact Award - 2007 Invited presentation at FBI-sponsored International Conference on Cyber Security –”A Global Solution to Emerging Cyber Threats”, New York City, January, 2009: http://www.iccs.fordham.edu/program.htm http://www.iccs.fordham.edu/program.htm

© Verizon Copyright 2009. 47 Next Steps for Verizon New vulnerability require a new mitigation technology for VoIP products –VoIP should not be deployed without protection SIP proxies are vulnerable to crash Attack tool is easy to build and use Carriers (e.g., Verizon) will need new network elements –RFP will include these requirements –Vendors must have a ready solution Conversion of research into a product that carriers can use –Need to determine optimal architecture for DoS prevention functionality for VoIP Security vs. Performance Hardware vs. Software Implementation –Proxy/Softswitch (SW) –SBC or New network element (HW/SW), Router? –Use internally (protect VZ Network) –Use externally (sell new security services to large customers) –Get other companies interested to synergize resources and share results

© Verizon Copyright 2009. 48 Next Steps for Verizon Cisco has just joined project funding research at NYU Polytechnic Institute to develop hardware prototype –Objective is to research the optimal hardware platform to implement Columbia- Verizon SIP algorithms –Use Cisco experimental cards that will eventually become router blades Continue relationship with Columbia –Cisco is funding maintenance of the Verizon testbeds For further research in distributed computing and traffic generation enhancements To assist NYU Poly in testing and validation of new prototype against previous benchmarks To assist in eventual product development during product testing cycle –Feedback loop of research and product cycle –Other research in related areas Proposal to study SRTP/RTSP What can we do to make the working relationship even more productive? –Have the synergistic combination of both CATT components (NYU Polytech and Columbia) and two major industry players (Cisco and Verizon) –A model worth emulating!

© Verizon Copyright 2009. 49 Potential Value to Cisco New vulnerability require a new mitigation technology for VoIP products –Verizon and other carriers will need new network elements –Eventually an RFP will include these requirements –Vendors must have a ready solution Incorporation of new technology/functionality into Cisco products, e.g., –Service Edge Routers (e.g., 6909/7609) –Enterprise Routers (e.g., 4000 series) Testbed support for product development –Setup unique laboratory facilities for VoIP security evaluations and product development testing In Columbia, prototype rapid development incubator In Verizon, incorporated Columbia/Verizon collaborative test tools for a more realistic complex IP-routed laboratory environment 49

© Verizon Copyright 2009. 50 Potential Value to Cisco Typical Verizon VoIP wireline architecture Possible use in wireless VoIP architectures –LTE plan contemplates migration to SIP Verizon IP/Data Network ALF SBC OLT ONT Phone AS SIP 2 SIP 1 GWR Softswitch Platform IDP Enterprise LAN Private IP Network VoIP Server 50

© Verizon Copyright 2009. 51 Conclusions Research Results –Demonstrated SIP vulnerabilities for VoIP resulting in new DoS susceptibility for both wireline and wireless Work is fully reusable to secure a “Presence” and IMS infrastructure –Implemented some “carrier-class” mitigation strategies Prototype is first of its kind in the world Removed SIP DoS traffic at carrier class rates Developed new generic requirements –Built a validation testbed to measure performance Developed customized test tools Built a high powered SIP-specific Dos Attack tool using parallel computing –Crashed a SIP Proxy in seconds Intellectual Property –Research activity resulted in six patent applications Commercialization –Licensing agreements currently under negotiation –Have socialized new requirements and test tools with vendor community to address rapid field deployment Major Vendors interested in new opportunities Rapid implementation is now expected Have created a partnership among both CATT university components and two major industry players

© Verizon Copyright 2009. Thank you Questions? gaston.s.ormazabal@verizon.com Paper published by Springer Verlag - “Principles, Systems and Applications of IP Telecommunications” in October 2008: http://www.springerlink.com/content/r5t1652v3572/ http://www.springerlink.com/content/r5t1652v3572/ Book available at: http://www.amazon.com/Principles-Applications-Telecommunications-Services- Generation/dp/354089053X/ref=sr_1_1?ie=UTF8&s=books&qid=1226098298&sr=1-1 http://www.amazon.com/Principles-Applications-Telecommunications-Services- Generation/dp/354089053X/ref=sr_1_1?ie=UTF8&s=books&qid=1226098298&sr=1-1

© Verizon Copyright 2009. 53 Next Steps - Next Steps - Possible New Projects Address Interception/Modification and Eavesdropping –Study of SRTP and associated protocols (SDES) –Comparison study of IPSec and TLS Study of SPIT prevention as a possible new service offering –Filtering of unwanted phone calls Intrusion Detection –Large scale call logs data analysis for DoS and ToS SIP DoS Testbed Maintenance and ongoing research –New machines (200 +)

© Verizon Copyright 2009. 56 SIP Threat Model details (1) Eavesdropping –Attacker can monitor signalling/media streams, but cannot or does not alter data itself –Signalling channel is not confidential –Call Pattern Tracking Discovery of identity, affiliation, presence –Traffic Capture Packet recording –Number harvesting Unauthorized collection of numbers, emails, SIP URIs

© Verizon Copyright 2009. 57 SIP Threat Model details (2) Impersonating of a SIP entity –Impersonate a UA Absense of assurance of a request's originator Registration Hijacking – attacker deregisters a legitimate contact and registers its own device for that contact –Impersonate a Server UAs should authenticate the server to whom they send requests Attacker impersonates a remote server and intercepts the UA's request

© Verizon Copyright 2009. 58 SIP Threat Model details (3) Interception and modification of SIP messages –Man-in-the-middle attack UA is using SIP to communicate media session keys –Call Re-routing Attacker might modify the SDP in order to route media streams to a wire-tapping device –Conversation Degradation Attacker might cause intentional reduction in QoS –False Call Identification Change “Subject” so message considered Spam

© Verizon Copyright 2009. 59 SIP Threat Model details (4) Service Abuse –Call Conference Abuse Hide identity for the purpose of committing fraud –Premium Rate Service Fraud Artificially increase traffic in order to maximize billing –Improper Bypass or Adjustment to Billing Avoid authorized service charge by altering billing records

© Verizon Copyright 2009. 61 Mitigation Prototype Implementation Firewall platform filters media and SIP proxy authentication attempts, and rate-limits messages based on “Method” specific controls –Utilizes wire-speed deep packet inspection –Thresholds are kept internal in the DPPM –State is only kept in Firewall in CAM tables Firewall controlling proxy model for media filtering and the authentication filter –Columbia's SIP Proxy sipd controls the Firewall Deep Packet Inspection Server –Utilize the Firewall Control Protocol to establish/insert filters in CAM table in real time SIP UAs being authentication challenged (IP, nonce) Media ports

© Verizon Copyright 2009. 62 Dynamic Pinhole Filtering SIP/2.0 200 OK From: c=IN IP4 128.59.19.162 m=audio 56432 RTP/AVP 0 INVITE sip:user1@proxy.com From: c=IN IP4 128.59.19.163 m=audio 43564 RTP/AVP 0 CAM Table SIPUA User2 SIPUA User1 128.59.19.163:43564 128.59.19.163:56432

© Verizon Copyright 2009. 63 Pinhole Problem Definition Problem parameterized along two independent vectors –Call Rate (calls/sec) Related to performance of SIP Proxy in Pentium –Concurrent Calls Related to performance of table lookup in IXP 2800 Data Collected in Excel spreadsheet format –{Number of concurrent calls, calls/sec, Opening delay, Closing delay, device} –SIP Proxy –SIP RAVE –Opening delay data provided in units of 20 ms packets –Closing delay data provided in units of 10 ms packets

© Verizon Copyright 2009. 65 SIP Security Overview Application Layer Security –SIP RFC 2543 – little security –SIP RFC 3261 – security enhancements Digest Authentication TLS IPSec –SRTP/ZRTP (RFC 3711) Perimeter Protection –SIP aware Filtering Mechanisms –SIP aware DOS Protection Detection and Mitigation

© Verizon Copyright 2009. 66 SIP Security Overview Application layer security Digest Authentication, TLS, S/MIME, IPSec, certificates SRTP/SDES/MIKEY/ZRTP for media Convergence leads to converged attacks –Data network attacks DDoS, spoofing, content alteration, platform attacks –Voice over IP network attacks Toll fraud, session hijacking, theft of service, spam/spit Most security problems are due to –User Datagram Protocol (UDP) instead of TCP/TLS –Plain text instead of S/MIME –Message/Method vulnerability –Flexible grammar --> syntax-based attacks

© Verizon Copyright 2009. 67 Pinhole Testing Methodology Generate external load on the firewall –SIPUA Loader/Handler in external load mode –Generates thousands of concurrent RTP sessions –For 30K concurrent calls have 120K open pinholes –CAM table length is 120K entries Search algorithm finds match in one cycle When external load is established, run the IEP analysis –SIPUA Loader/Handler in internal load mode –Port scanning and Protocol analyzer –Increment calls/sec rate Measure pinhole opening and closing delays Detect pinholes extraneously open

© Verizon Copyright 2009. 69 Theft of Service Overview VoIP is different –Not a static but a real-time application –Direct comparisons with PSTN According to Subex Azure 3% of total revenue is subject to “fraud”* VoIP can be expected to be at least twice as large a proportion of revenue –Theft of Service is more daunting problem in VoIP Implications of ToS –Lost revenue and bad reputation –Abused resources cause monetary losses to network providers –Unauthorized usage degrades whole system’s performance Scenarios –Using services without paying –Illegal Resource Sharing (unlimited-plans) –Compromised Systems –Call Spoofing and Vishing *Billing World and OSS Magazine: “Top Telco Frauds and How to Stop Them”, January 2007, by Geoff Ibett

© Verizon Copyright 2009. 70 Simplified Billing Model End-Points –Different devices can be used to connect a SIP server Information Exchange –User data from end-points to SIP server should be protected –Communication between SIP server and Authorization server should be safe from eavesdropping attacks Billing –DIAMETER should be secured to avoid billing attacks Recommended IPSec with Encryption –Authorization server must be hardened to avoid OS attacks

© Verizon Copyright 2009. 71 Theft of Service Research Goals Verification of security implementation –Automate validation process Creating new tools and scripts Modify existing tools to create a package Architectural Integrity Verification Tool –Identity Assurance –Multiple End Points –Intrusion Detection Black-box type abstraction

© Verizon Copyright 2009. 72 Theft of Service Challenges Client-side threats –Illegal resource sharing –Compromised hardware –Weak password Server-side threats –Identity assurance Unauthorized registration, unauthenticated INVITE Digest authentication (nonce usage, password guessing) Transport protocol choice (TCP/UDP) TLS crypto strength –Spoofing to gain privileged access –DoS/DDoS attacks Implementation flaws Flooding billing system –DoS amplification prevention on Billing systems Application level flaws –Counter Method-based vulnerabilities –BYE attack validation

© Verizon Copyright 2009. 73 Theft of Service Challenges Service threats –Distinguish between audio call, single media stream or multiple destination signaling Multimedia services, messages, etc. –Launching multiple simultaneous accounts Multiple end-points –Authorization Safeguards 800 numbers, emergency number Voicemail messages checking portability ensured Intrusion detection Existing call logs help find patterns and detect anomaly

© Verizon Copyright 2009. 74 secureSIP Identity Assurance Why do we need Identity Assurance? –Digest authentication is only as strong as password –Weak authentication  false sense of security –Without Identity Assurance, difficult to backtrack to actual offender in any planned attack on network TLS and S/MIME are future solutions Password Guessing –Easy to crack weak passwords by dictionary attack –Compromised passwords can result in legal and financial implications for network provider –CrackLib contains 1.6 million most common passwords, available freely online

© Verizon Copyright 2009. 75 secureSIP Identity Assurance Multiple password lists –choose password list suitable for experiment –extend any list, or simply add new one Configurable speed of attack –option to launch fast, medium-paced or slow attack on authentication server Utilizes distributed network power –all machines work in parallel to crack password –1 million passwords in 100 seconds Verification against standard SIP components –OpenSER used for doing identity assurance

© Verizon Copyright 2009. 76 secureSIP Multiple End Points Single “Address of Record” but multiple URIs makes problem more challenging Intentional resource sharing –Problem: Users can intentionally misuse network resources from various end-points –Solution: Geographical co-relation across space and time Space: E.164 TN, URI, IP address Temporal: timestamp (call log)

© Verizon Copyright 2009. 77 secureSIP Multiple End Points Geographical location matching –Maps IP address to precise geographical location –Maxmind.com toolkit for accurate IP to location lookup –Area code also suggests location, IP is more precise SIP log parser –Parses uploaded log file containing SIP traffic –Filters data into individual fields, puts it in database Analyzer –Finds anomalies in call origin location and time –IP address for geographical location of a user –Statistical modelling temporal usage patterns, geographical usage patterns –Comparison of observed location patterns and time intervals to pre-defined thresholds –Minimize false positives and false negatives

© Verizon Copyright 2009. 78 secureSIP Intrusion Detection Why do we need Intrusion Detection? –Unintentional resource sharing Botnets, zombies can cause unreasonable load Password authentication, encryption fails –Spam, SPIT and identity theft Analyze patterns of incoming calls to network –Turing Test See network wide pattern to detect fraud at the outset Captures suspicious activity that may slip through firewall rules

© Verizon Copyright 2009. 79 secureSIP Intrusion Detection Intrusion Detection –Out-of-domain SIP requests –Suspicious BYE and INVITE –Behavioural and knowledge-based techniques Minimize classic DoS attacks –Session tear down, media modification –Billing server attack, call hijacking Analyze historical call logs –Synthetic vs. Real (Verizon Business) Need to develop a Security Event Management system – Analyze and correlate information provided by verification tool to detect, mitigate and prevent ToS

© Verizon Copyright 2009. 80 secureSIP Controller Controller –Automated Web-based Control Software run on SUN box –Ability to configure attack traffic on the fly Development Platform –Perl, MySQL and in-built web-server –Operating system independent, can be accessed remotely Results Analyzer –Gathers, analyzes and correlates results –Measurement progress is saved to database in real-time –Controller analyzes results from database and aggregates them to present real-time statistics

© Verizon Copyright 2009. 81 Validation Strategy Methodology for Anti Spoofing Use the SIPp and SIPStone testing tools in a distributed environment to generate legitimate and attack SIP traffic respectively –Generate both legitimate and spoofed source address requests Measure the following calls/sec throughput values: –Legitimate requests, without authentication (C apacity ) –Legitimate requests, with authentication (N ormal ) –Legitimate (N ormal ) and spoofed requests (SA ttacknof ), without filters –Legitimate (N ormal ) and spoofed requests (SA ttackf ), with filters (D efense ) Identify the impact of spoofed addresses floods on the calls/sec rate of legitimate requests –Expect to see S A ttackf << S A ttacknof, and ideally, D = N –Calculate False Positive and False Negative rates from measurements: FP= ( N ormal - D efense )/N ormal FN= SA ttackf / SA ttacknof

© Verizon Copyright 2009. 82 Validation Strategy Methodology for Rate Limiting Use the SIPp and SIPStone testing tools in a distributed environment to generate legitimate and attack SIP traffic respectively –Generate both legitimate and spoofed source address requests Measure the following calls/sec throughput values: –Legitimate requests, without authentication (C apacity ) –Legitimate requests, with authentication (N ormal ) –Legitimate (N ormal ) and Method requests/response/OoS (MA ttacknof ), without filters –Legitimate (N ormal ) and Method requests/response/OoS (MA ttackf ), with filters (D efense ) Identify the impact of spoofed addresses floods on the calls/sec rate of legitimate requests –Expect to see MA ttackf << MA ttacknof, and ideally, D = N –Calculate False Positive and False Negative rates from measurements: FP= ( N ormal - D efense )/N ormal FN= MA ttackf / MA ttacknof

© Verizon Copyright 2009. 83 Dialog Filtering Filtering based on Dialog parameters –Broader “brushstroke” than Transaction level –Only useful with floods of CANCEL or BYE requests Identify a BYE message by its Dialog-ID Maintain a database of INVITE sources (Contacts) Verify and accept a BYE message only from legitimate source addresses Reject it if it is not a part of an existing dialog

© Verizon Copyright 2009. 84 Transaction State Machine Filtering Validates the state of each SIP transaction for each message received Maintain state per transaction as per the state machine specified in RFC 3261 –Client and Server –INVITE and Non-INVITE transactions Maintain the state table The filter allows only “in-state” messages and not allow “out-of-state” messages

© Verizon Copyright 2009. 85 Verizon Business Impact SIP DoS work –Global Network Engineering & Planning Organization Support Technology organization to define new security architecture for VoIP Services –Network & Information Security Organization “Better Security Reviews” of Advantage VoIP Service –Global Customer Service & Provisioning Organization Sales Engineering – Premier Accounts Team Briefing SIP ToS work –Office of Chief Financial Officer Credit&Collections

© Verizon Copyright 2009. June 23, 2015 Columbia - Verizon Research Secure SIP: Scalable DoS Prevention Mechanisms for SIP- based VoIP Systems, and Validation.

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© Verizon Copyright 2009. June 23, 2015 Columbia - Verizon Research Secure SIP: Scalable DoS Prevention Mechanisms for SIP- based VoIP Systems, and Validation.

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Presentation on theme: "© Verizon Copyright 2009. June 23, 2015 Columbia - Verizon Research Secure SIP: Scalable DoS Prevention Mechanisms for SIP- based VoIP Systems, and Validation."— Presentation transcript:

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