1. 802.1x What it is, How it’s broken, and How to fix it.
Bruce Potter
The Shmoo Group
Practitioner, not researcher
Talk will focus on the operational impact of 802.1x, not the low level technical breakdown.

2. Drive 12 miles to work in Northern VA, much of it through un-developed land.
In Sept, there were 12 AP’s. In May there were 50.

3. Why Wireless? No cable plant Enhanced mobility Ad hoc relationships
Lower cost (initially… TCO may be higher)
Rapid deployment
Enhanced mobility
Ad hoc relationships
Many different requirements
talk about TCO

4. Why Not Wireless No physical security Low throughput
Unregulated, noisy bands
Snooping raw packets is trivial

5. 802.11, b, etc.
IEEE standard – based on well known Ethernet standards
– FHSS or DSSS, WEP, 2.4 GHz, Infrastructure (BSS) or Ad-Hoc (iBSS)
Limited to 2Mb/s due to FCC limits on dwell times per frequency hop
802.11b – DSSS only, WEP, 2.4 GHz, Infrastructure or Ad-Hoc
Up to 11Mb/s
Also known as Wi-Fi
802.11a and g

6. An Association Associations are a basic part of 802.11
Client Requests authentication
AP responds with auth type (Open/WEP)
Authentication is performed
If successful, then Association is requested and granted
SSID is sent in the clear, so not advertising SSID is NOT a valid security mechanism

7. General Principles Deal with the basics
Integrity
Protecting your packets from modification by other parties
Confidentiality
Keeping eavesdroppers within range from gaining useful information
Keeping unauthorized users off the network
Free Internet!
Risks to both internal and external network
Availability
Low level DoS is hard to prevent
Like any other environment, there are no silver bullets

8. Current Security Practices
WEP –Wired Equivalent Privacy
Link Level
Very Broken
Firewalls/MAC Filtering
Reactionary – IDS/Active Portal
Higher level protocols

9. WEP In a Nutshell 40 bits of security == 64 bits of marketing spam.
Not just encryption, also rudimentary authentication of AP’s and clients.

10. Thoughts on WEP
Key management beyond a handful of people is impossible
Too much trust
Difficult administration
Key lifetime can get very short in an enterprise
No authentication for management frames
No per packet auth
False Advertising!!!

11. What is Lacking? Scalability Protection for all parties
Many clients
Large networks
Protection for all parties
Eliminate invalid trust assumptions

12. 802.1x
Port based authentication for all IEEE 802 networks (layer 2 authentication)
Originally for Campus networks
Extended for wireless
Allows for unified AAA services
Provides means for key transport
NOT A WIRELESS PROTOCOL!!!
Does not specify means for key transport

13. May not be Access Point… Originally it was a wired switch.

14. Pre-Authentication State

15. Post-Authentication State

16. EAP Extensible Authentication Protocol Originally designed for PPP
Shoehorned into 802.1x
Switch/Access point is a pass through for EAP traffic. New authentication mechanisms do not require infrastructure upgrades
LEAP – Cisco’s Lightweight EAP
Password based and (relatively) widely available
De facto mechanism between AS and AServ is RADIUS

18. EAP Methods
EAP-TLS: Uses certs! If implemented properly, solves many problems
TTLS – Tunneled TLS. Allows encapsulation of other auth mechanisms.
“machine” auth’d by TLS, person by the tunneled protocol
PEAP – IETF Draft
Like TTLS but with another EAP method encapsulated
TLS/TTLS and others require certs
We all have a PKI setup, right? and use it properly and regularly?

19. What’s Right Protection of the infrastructure
Authentication mechanism can
change as needed
address flaws in existing wireless security
Lightweight
No encapsulation, no per packet overhead… simply periodic authentication transactions

20. What’s Right
In controlled environment, risks can be mitigated by higher level protocols
VPN/SSL/SSH
NOTE: exchange of WEP key material is not part of 802.1x specification
Remember: designed for wired campus networks

21. What’s Right Association happens BEFORE 802.1x transaction.
Good: If 802.1x session is protected by default WEP key then the attacker must first compromise the WEP key to make use of 802.1x vulns
Bad: Key management anyone? Just how does the default key get there?

22. What’s Wrong www.missl.cs.umd.edu/wireless/1x.pdf
First Open source supplicant
First holes in 802.1x
One way authentication
Less of a concern in LAN environment
Traffic Interception
Session Highjacking

23. What’s Wrong – Technical
One way Authentication
Gateway authenticates the client
Client has no explicit means to authenticate the Gateway
Rouge gateways put client at risk
Remember – the loudest access point wins
Still no Authentication of management frames (assoc/deassoc/beacons/etc…)
Some EAP methods provide mutual authentication… but it’s not a requirement.

24. What’s Wrong - Technical
MITM
Send “Authentication Successful” to client
Client associates with malicious AP
Hijacking
Send deassociation message to client… AP is in the dark
Change MAC to client and have live connection

25. What’s Wrong – Technical
RADIUS uses shared secret with the Authenticator
Same issue as WEP, but on a more reasonable scale
Authentication after association presents roaming problems
Authentication takes a non-trivial amount of time… can disrupt data in transit
Failure of RADIUS server == failure of network
Many AP implementations don’t allow multiple RADIUS servers
Most RADIUS server failover is non-transparent

26. What’s Wrong – touchy feely
They forgot about the client (trust assumptions)
Everyone is ask risk
Everyone is a threat
Lack of physical security requires encrypted channel to secure 802.1x
Wired “port” is not the same as wireless “port”
Protocol designed to not require hardware replacement
Leads to less than stellar solution, esp WRT authentication of management frames.

27. What’s Wrong – touchy feely
Extensibility leads to complexity
Complexity leads to mistakes in implementation
Read the MS Guide on create EAP methods as an example.
Multivendor support is difficult
Using a shoehorn to force protocols to work together leads to problems

28. Why Did it Go Wrong? 802.1x – Designed for Campus networks
EAP – Designed for PPP
NEITHER designed with wireless threat model in mind
Lesson: Don’t apply old protocols to new problems without understanding the risk.

29. Where Are We Today? Several 802.1x implementations available
Windows XP (not PocketPC 2002)
Open1x.org
EAP implementations
Windows IAS
FreeRADIUS – MD5 and TLS
Cisco
Other RADIUS servers
NOTE: highest risk applications don’t have 802.1x – Pocket PC2k

30. Where Are We Today? 802.1x capable Access Points Cisco Lucent
RG1000/RG1100 can be hacked with AP500 firmware to become 1x capable
Some drawbacks
OS authenticator from open1x.org
others

31. What’s Next Integration of existing solutions to “raise the bar”
Limited 802.1x implementations
802.11i (Task Group I – Security)
On track… the right track
Mutual auth, per packet auth
802.1x a part of

32. What’s Next WEP has the right idea
End to End Solutions ala SSL, SSH, IPSec
Not likely
PocketPC2k2 doesn’t have a robust cert infrastrucuture.

33. Temporal Key Integrity Protocol
Fast Packet Keying
Packet MAC
Dynamic Rekeying
Key distribution via 802.1x
3Q product deployment
Still RC4 based to be backward compatible
AES with 802.1x keying in the distant future

34. Questions