The AVISPA Project: Automated Validation of Internet Security Protocols and Applications

Automated Validation of Internet Security Protocols and ApplicationsShared cost RTD (FET open) project IST-2001-39252

The AVISPA Project:Automated Validation of Internet Security Protocols

and Applications

62th IETF

Minneapolis

March 2005

Alessandro ArmandoAI-Lab, DIST – University of Genova, Italy

62th IETF, MinneapolisMarch 10, 2005 2

A. Armando

Motivation

• The number and scale of new security protocols under development is out-pacing the human ability to rigorously analyze and validate them.

• To speed up the development of the next generation of security protocols and to improve their security, it is of utmost importance to have

– tools that support the rigorous analysis of security protocols

– by either finding flaws or establishing their correctness.

• Optimally, these tools should be completely automated, robust, expressive, and easily usable, so that they can be integrated into the protocol development and standardization processes.


A. Armando

Context

• A number of (semi-)automated protocol analyzers have been proposed, BUT

• Automatic anaysis limited to small and medium-scale protocols

– scaling up to large-scale Internet security protocols is a considerable challenge, both scientific and technological;

• Each tool comes with its own specification language and user interface;


A. Armando

Objectives of AVISPA

• Develop a rich specification language for formalizing industrial strength security protocols and their properties.

• Advance state-of-the-art analysis techniques to scale up to this complexity.

• Develop an integrated tool supporting the protocol designer in the debugging and validation of security protocols: the AVISPA Tool.

• Assess the tool on a large collection of practically relevant, industrial protocols.

• Migrate this technology to companies and standardisation organisations.


A. Armando

The AVISPA Tool

• Push-button security protocol analyzer

• Supports the specification security protocols and properties via a rich protocol specification language

• Integrates different back-ends implementing a variety of state-of-the-art automatic analysis techniques.

• User interaction facilitated by:

– Emacs mode

– Web interface

• To the best of our knowledge, no other tool exhibits the same level of scope and robustness while enjoying the same performance and scalability.


A. Armando

Architecture of the AVISPA Tool


A. Armando

The Dolev-Yao Intruder Model

D-Y Intruder may:• Intercept/emit messages• Decrypt/encrypt with known key (Black-box perfect crypto)• Split/form messages• Use public information• Generate fresh data

channel: data + Control msgs

trustworthydevice

trustworthydevice

{A, nA} KeyB {A, nI} KeyB

A, nI, KeyA, KeyB

Intruder Knowledge


A. Armando

The Back-ends

• The On-the-fly Model-Checker (OFMC) performs protocol analysis by exploring the transition system in a demand-driven way.

• The Constraint-Logic-based Attack Searcher (CL-AtSe) applies constraint solving with powerful simplification heuristics and redundancy elimination techniques.

• The SAT-based Model-Checker (SATMC) builds a propositional formula encoding all the possible attacks (of bounded length) on the protocol and feeds the result to a SAT solver.

• TA4SP (Tree Automata based on Automatic Approximations for th Analysis of Security Protocols) approximates the intruder knowledge by using regular tree languages.


A. Armando

The High Level Protocol Specification Language (HLPSL)

• Role-based language:

– a role for each (honest) agent

– parallel and sequential composition glue roles together

• The HLPSL enjoys both

– a declarative semantics based on a fragment of the Lamport’s Temporal Logic of Actions and

– an operational semantics based on a translation into a rewrite-base formalism: the Intermediate Format (IF).

• Intruder is modeled by the channel(s) over which the communication takes places.


A. Armando

Basic Roles

role Basic_Role (…)

played_by … def=

owns {θ: Θ}

local {ε}

init Init

accepts Accept

transition

event1 action1

event2 action2

…

end role

role Alice (A, B: agent, Ka, Kb: public_key, SND, RCV: channel (dy)) played_by A def= local State:nat, Na:text (fresh), Nb:text init State = 0

transition 1. State =0 /\ RCV(start) =|> State'=2 /\ SND({Na'.A}_Kb) /\ witness(A,B,na,Na') 2. State =2 /\ RCV({Na.Nb'}_Ka) =|> State'=4 /\ SND({Nb'}_Kb) /\ request(A,B,nb,Nb') /\ secret(Na,B)end role

General Pattern Initiator Role in NSPK


A. Armando

Composed Roles: Parallel Composition

role Par_Role (…)

def=

owns {θ:Θ}

local {ε}

init Init

accepts Accept

composition

A B

end role

Pattern Example

role Kerberos (..) composition Client /\ Authn_Server /\ TGS /\ Serverend role


A. Armando

Composed Roles: Sequential Composition

role Seq_Role (…)

def=

owns {θ:Θ}

local {ε}

init Init

accepts Accept

composition

A ; B

end role

General Pattern Example

role Alice (..) establish_TLS_Tunnel(server_ authn_only); present_credentials; main_protocol(request, response)end role


A. Armando

The AVISPA Web Interface

The AVISPA Tool can be freely accessed at the URL

http://www.avispa-project.org/web-interface

The interface features:

• A simple editor for HLSPL specifications

• Basic/Expert user modes

• Attacks are graphically rendered with message-sequence charts


A. Armando


A. Armando

The AVISPA Library

• We have selected a substantial set of security problems associated with protocols that have recently been or are currently being standardized by the IETF.

• We have formalized in HLPSL a large subset of these protocols; the result of this specification effort is the AVISPA Library.

• At present the AVISPA Library comprises 112 security problems derived from 33 protocols.

• We have thoroughly assessed the AVISPA Tool by running it against the AVISPA Library.


A. Armando

Assessment of the AVISPA Tool

Protocol Properties Attacks TimeUMTS_AKA 3 0 0,01AAAMobileIP 7 0 0,20ISO-PK1 1 1 0,00ISO-PK2 1 0 0,00ISO-PK3 2 2 0,01ISO-PK4 2 0 0,03LPD-MSR 2 2 0,02LPD-IMSR 2 0 0,01CHAPv2 3 0 0,01EKE 3 2 0,04TLS 3 0 0,32DHCP-delayed 2 0 0,00Kerb-Cross-Realm 8 0 4,14Kerb-Ticket-Cache 6 0 0,38Kerb-V 8 0 0,42Kerb-Forwardable 6 0 10,89Kerb-PKINIT 7 0 0,64Kerb-preauth 7 0 0,62

Protocol Properties Attacks TimeCRAM-MD5 2 0 0,40PKB 1 1 0,01PKB-fix 2 0 0,88SRP_siemens 3 0 2,86EKE2 3 0 0,16SPEKE 3 0 3,11IKEv2-CHILD 3 0 1,19IKEv2-DS 3 1 5,22IKEv2-DSx 3 0 42,56IKEv2-MAC 3 0 8,03IKEv2-MACx 3 0 40,54h.530 3 1 0,64h.530-fix 3 0 4.277,54lipkey-spkm-known 2 0 0,23lipkey-spkm-unknown 2 0 7,33


A. Armando

Coverage of the AVISPA Library

Wide range of protocols and security properties:

• 11 different areas (in 33 groups)

• 5 IP layers

• 20+ security goals (as understood at IETF, 3GPP, OMA, etc)


A. Armando

Coverage of established IETF Security Specifications

AVISPA covers 86% (24 of the 28) “recommended" Security Protocols (plus very current ones)

AVISPAcontainers primitives Systems Other Total

"Core"5 1 1 7

"Useful"9 2 3 3 17

8 2 2 1 13

18 3 21

24 3 3 4 4 38GSS, hashes, Firewalls , Ipsec,

Sasl, signatures, +transversalPGP,EAP certificate

profilesAPI CMP,

PfKey

IETF Recommendation

IAB Recommendation(RFC 2316)

Security mechanisms (RFC 3631)

Authentication Mechanisms (ID)

No of different Specifications

ID = draft-iab-auth-mech-03.txt (expired)


A. Armando

Verification is starting to make a difference

H.323MT

V-GK MRP H-BE AuF

1.) GRQ( EPID, GKID, 0, CH1,T1, g

x, HMACZZ(GRQ))

13.) GCF(GKID, EPID, CH1, CH2, (T13), g

y, HMACZZ(W), HMACZZ(GKID), HMACK(GCF))

14.) RRQ(EPID, GKID, CH2, CH3,(T14), HMACK(RRQ))

2.) RIP(...)

15.) RCF(GKID, EPID, CH3, CH4,(T15), HMACK(RCF))

V-BE MRP

4.) 5.) 6.) 7.)

12.) 11.) 10.) 9.) 8.)

3.)

compute DH: gx mod p

compute DH: gy mod pW:= gx gy

K:= gxy mod p

K:= gxy mod pW:= gx gy

AuthenticationRequest (GRQ(..), GKID, W, HMAC)

AuthenticationConfirmation (W, HMACZZ(W), HMACZZ(GKID), HMAC)

H.530

MS SN HEADR

ADS(AV1,.. AVn)UAR(chall)

UAS(resp)

LUR

SynchronFailure

UMTS-AKA


A. Armando

The AVISPA Teams

• University of Genoa, Italy: A. Armando (project coordinator), L. Compagna, G. Delzanno, J. Mantovani

• INRIA Lorraine, France: M. Rusinowitch, Y. Chevalier, J. Santiago, M. Turuani, L. Vigneron, O. Kouchnarenko, P.-C. Heam, Y. Boichut

• ETH Zurich, Switzerland, D. Basin, Paul Drielsma, S. Moedersheim, L. Vigano`

• Siemens AG, Germany: J. Cuellar, D. von Oheimb, P. Warkentin


A. Armando

Conclusions

• The AVISPA Tool is a state-of-the-art, integrated environment for the automatic analysis and validation of Internet security protocols.

• Try it at http://www.avispa-project.org/web-interface !

• More information at http://www.avispa-project.org

• If you use the AVISPA Tool, please don’t hesitate to ask!

– We are happy to help.

– Your feedback is very important to us.


A. Armando

Outlook: New Problems offer new Challenges

• Internet offers agent many identities

– user, ip, mac, tcp port, ... What is “A”, “ID_A”?

• Many types of DoS attacks

– flooding, bombing, starving, disrupting

• New types of properties

– fairness, abuse-freeness, timeliness, effectiveness

– DoS

– key control, perfect forward secrecy, ...

– layered properties

• if attacker ... then ..., if attacker ... then ...

• Not only Communication Channels

– Viruses, Trojan Horses, APIs

– Trust Problem (e.g. TCP)


A. Armando

Extra Slides


A. Armando

Proving protocols correct

The AVISPA Tool proves in a few minutes that a number ofprotocols in the library guarantee secrecy:

• EKE• EKE2• IKEv2-CHILD• IKEv2-MAC• TLS• UMTS_AKA• CHAPv2


A. Armando

The HLPSL2IF Translator

• HLPSL specifications are translated into equivalent IF specifications by the HLPSL2IF translator.

• An IF specification describes an infinite-state transition system amenable to formal analysis.

• IF specifications can be generated both in an untyped variant and in a typed one, which abstracts away type-flaw attacks (if any) from the protocol.


A. Armando

Security relevant protocols: Areas

• Infrastructure (DHCP, DNS, BGP, stime)

• Network Access (WLAN, pana)

• Mobility (Mobile IP, UMTS-AKA, seamoby)

• VoIP, messaging, presence (SIP, ITU-T H530, impp, simple)

• Internet Security (IKE (IPsec Key agreement), TLS, Kerberos, EAP, OTP, Sacred, ssh, telnet,...)

• Privacy (Geopriv)

• AAA, Identity Management, Single Sign On (Liberty Alliance)

• Security for QoS, etc. (NSIS)

• Broadcast/Multicast Authentication (TESLA)

• E-Commerce (Payment)

• Secure Download, Content protection (DRM)


A. Armando

Security Goals

• Authentication + Secrecy (unicast + multicast)– Peer Entity , Data Origin, Implicit Destination Authn, Replay Protection

• Authorisation (by a Trusted Third Party)• Key Agreement Properties

– Perfect Forward Secrecy (PFS)– Secure capabilities negotiation – (Resistance against Downgrading and Negotiation Attacks)

• “Anonymity”– Identity Protection against Peer

• Non-repudiation – Proof of Origin– Proof of Delivery– “Accountability”

• Limited DoS Resistance• Sender Invariance• Temporal Logic Properties (Fair Exchange, Service Delivery)• Session Formation• Consistent View• Key naming

Documents

The AVISPA Project: Automated Validation of Internet Security Protocols and Applications