1. EE579T/GD_6 #1 Summer 2003 © 2000-2003, Richard A. Stanley EE579T Network Security 8: Wireless Security Prof. Richard A. Stanley

2. EE579T/GD_6 #2 Summer 2003 © 2000-2003, Richard A. Stanley Overview of Today’s Class Administrivia Review last week’s lesson Security in the news Wireless security

3. EE579T/GD_6 #3 Summer 2003 © 2000-2003, Richard A. Stanley Reminders Wednesday, September 3: class at usual time with project presentations Final for this course is take-home –Final exam will be distributed on project day –Exam is due 17 September We start the next class on Sept. 8th

4. EE579T/GD_6 #4 Summer 2003 © 2000-2003, Richard A. Stanley SNMP Summary SNMP is widely-used for managing clients distributed across a network SNMPv1 is simple, effective, and provides the majority of SNMP service in the field SNMPv2 adds some functionality to v1 SNMPv3 is a security overlay for either version, not a standalone replacement SNMP security is a major issue!

5. EE579T/GD_6 #5 Summer 2003 © 2000-2003, Richard A. Stanley IDS Summary IDS’s can be useful in monitoring networks for intrusions and policy violations Up-to-date attack signatures and policy implementations essential Many types of IDS available, at least one as freeware Serious potential legal implications Automated responses to be avoided

6. EE579T/GD_6 #6 Summer 2003 © 2000-2003, Richard A. Stanley News Items It has been a great fortnight for viruses –Blaster (a.k.a. Lovsan) worm Exploits flaw in Windows NT, 2000 and XP; drops a malicious program on your computer to force frequent reboots Blamed for safety system failures in Ohio nuclear power system, and for commuter rail outages in Washington, DC area caused by failure of the CSX railway signaling system

7. EE579T/GD_6 #7 Summer 2003 © 2000-2003, Richard A. Stanley But Wait, There’s More! Nachi worm –Spreads by exploiting a hole in Microsoft Windows. Instructs remote target system to download and execute the worm from the infected host. Once running, the worm terminates and deletes the W32/Lovsan.worm.a process and applies the Microsoft patch to prevent other threats from infecting the system through the same hole. When the system clock reaches Jan 1, 2004, the worm will delete itself upon execution. –Is this good or bad?

8. EE579T/GD_6 #8 Summer 2003 © 2000-2003, Richard A. Stanley And Still More... SoBig worm –arrives as an email attachment with a.pif or.scr extension. When run, it infects the host computer, then emails itself (using its own SMTP engine) to harvested email addresses from the victim's machine. –worm "spoofs" the "from: field", using one of the harvested email addresses –saps bandwidth and slows network performance. –can also open up a user's computer port –believed to have planted hostile code seeking further instructions

9. EE579T/GD_6 #9 Summer 2003 © 2000-2003, Richard A. Stanley Wireless Security: What’s the Problem? Rapid, extensive wireless deployment Little to no installation RF engineering Ineffective built-in security protocols Lack of awareness of ways that wireless access can compromise networks –Inadvertently –Maliciously

10. EE579T/GD_6 #10 Summer 2003 © 2000-2003, Richard A. Stanley Standards This is new territory Until the late 1990’s, no overall standards existed for WLANs –Each manufacturer did their own thing –Interoperability virtually nonexistent Cross-vendor operability still an issue in some settings

11. EE579T/GD_6 #11 Summer 2003 © 2000-2003, Richard A. Stanley WLANs Today Are Largely Standardized Dominant -- but not only -- standard is IEEE 802.11x –802.11b: currently most popular, large $$ 2.4 gHz ISM band, DSSS, 1-11 MBps –802.11a: about to take over? 5 gHz UNII band, OFDM, up to 54 MBps –802.11i: coming on fast, includes integrated, improved security features Intended to be 802.11a compatible Single standard allows intruders to focus their efforts to maximum effect Incompatible

12. EE579T/GD_6 #12 Summer 2003 © 2000-2003, Richard A. Stanley Most Common WLAN Standards

13. EE579T/GD_6 #13 Summer 2003 © 2000-2003, Richard A. Stanley WLANs Don’t Usually Stand Alone Wireless LANs are usually extensions to wired LANs, using access points (AP) –An AP functions as an IP bridge between the wired and wireless media While all-wireless LANs are possible, they are uncommon as intentional configurations

14. EE579T/GD_6 #14 Summer 2003 © 2000-2003, Richard A. Stanley WLAN Operation Probes –Signals from clients seeking to connect –Elicit response from potential APs –Connection established w/strongest signal Beacons –Advertise presence and ID of AP –Provide public notice of network presence

15. EE579T/GD_6 #15 Summer 2003 © 2000-2003, Richard A. Stanley Typical WLAN Topology AP

16. EE579T/GD_6 #16 Summer 2003 © 2000-2003, Richard A. Stanley But What If The Topology Actually Looks Like This? Unauthorized Client

17. EE579T/GD_6 #17 Summer 2003 © 2000-2003, Richard A. Stanley Internal Security Vulnerabilities Rogue WLANs –Created by unauthorized APs on network –Modern computer configurations facilitate Accidental Associations –WLAN client inadvertently associating with another network within range Insecure Network Configurations

18. EE579T/GD_6 #18 Summer 2003 © 2000-2003, Richard A. Stanley External Security Vulnerabilities Eavesdropping –Common, easy to do Denial of service & interference –Simply a jamming problem Masquerade –Capture legitimate info, use to log on Man-in-the-middle attacks

19. EE579T/GD_6 #19 Summer 2003 © 2000-2003, Richard A. Stanley RF Engineering Issues Most WLANs are installed without benefit of detailed RF engineering Access points, although low power, still can cover a large geographic area Addition of directional antennas to AP or receiver can further extend range

20. EE579T/GD_6 #20 Summer 2003 © 2000-2003, Richard A. Stanley RF Issues Mapping the coverage of your APs is critical, but seldom done Widely available data on WLAN coverage that can be used for “free” service It isn’t just your system. What about overlapping coverage from your neighbors?

21. EE579T/GD_6 #21 Summer 2003 © 2000-2003, Richard A. Stanley Measured Coverage of One Access Point in Lawrence, KS It was intended to cover only the interior of the building in red!

22. EE579T/GD_6 #22 Summer 2003 © 2000-2003, Richard A. Stanley Northeast US Wi-Fi Coverage

23. EE579T/GD_6 #23 Summer 2003 © 2000-2003, Richard A. Stanley Free Wi-Fi in NYC (one view)

24. EE579T/GD_6 #24 Summer 2003 © 2000-2003, Richard A. Stanley Rogue WLANs “Standard” computer configuration today includes WLAN NIC, especially on laptops (cf. Intel Centrino ® ) Result is same as when modems connecting around the firewall were the primary problem User may be totally unaware W/L device is activated and in use

25. EE579T/GD_6 #25 Summer 2003 © 2000-2003, Richard A. Stanley Inadvertent Association When the client can “see” multiple APs, it may be difficult to force it to associate with the correct one Result: network client connected to foreign network, which can leak sensitive info and anything else available over the network

26. EE579T/GD_6 #26 Summer 2003 © 2000-2003, Richard A. Stanley Insecure Configurations Default settings SSID broadcast Weak or no encryption Weak authentication Beware the “helpful” employee or the power-up reset menu!

27. EE579T/GD_6 #27 Summer 2003 © 2000-2003, Richard A. Stanley Configuration Settings As with so many other network elements, many default settings remain at their factory setting in deployed nets SSIDs should always be changed from the default, and rarely broadcast –This makes it harder, but far from impossible, for intruders to “find” the net

28. EE579T/GD_6 #28 Summer 2003 © 2000-2003, Richard A. Stanley WEP: Too Literal An Implementation WEP=Wired Equivalent Privacy –That’s exactly what it provides, perhaps even better than that –Problem? That isn’t enough Wired signals are confined to cables (mostly) Wireless signals are available to all listeners Although flawed, WEP is better than nothing, but most users turn it off

29. EE579T/GD_6 #29 Summer 2003 © 2000-2003, Richard A. Stanley Origins of WEP Marketing and Political Issues: –Developed as part of a wireless LAN research project at Apple Computer, Inc. –Eavesdropping was perceived as a barrier to market acceptance –Apple sells into a worldwide market so solution had to be exportable –When WEP developed, NSA allowed only 40- bit encryption to be exported

30. EE579T/GD_6 #30 Summer 2003 © 2000-2003, Richard A. Stanley Origins of WEP (cont.) Technical Issues: –Eavesdropping on wireless link => privacy and authentication problems –Multiple network protocols (in 1993) => solution required at data link layer –Data link layer is “best effort” => crypto-state (other than shared key) must accompany each frame

31. EE579T/GD_6 #31 Summer 2003 © 2000-2003, Richard A. Stanley WEP Solution Apple had unlimited RC4 license from RSA, Inc. Method and apparatus for variable- overhead cached encryption, US Patent 5,345,508 applied for 23 Aug 1993, granted 6 Sept 1994 Licensed for export in mid-1994

32. EE579T/GD_6 #32 Summer 2003 © 2000-2003, Richard A. Stanley WEP Encryption + Initialization Vector (IV) Secret Key Plaintext + Seed PRNG RC4() Ciphertext Cache Key Sequence (MAX_MSG_SZ) IV The problems with this approach are obvious!

33. EE579T/GD_6 #33 Summer 2003 © 2000-2003, Richard A. Stanley IEEE 802.11’s use of WEP WEP introduced in March 1994 Strong pushback in standards committee regarding cost and overhead of encryption Dilution of proposal; privacy in 802.11x made optional –By default, WEP is not activated in 802.11x devices; requires positive user intervention

34. EE579T/GD_6 #34 Summer 2003 © 2000-2003, Richard A. Stanley WEP Security Problems Papers submitted to 802.11 committee highlight the problems with WEP; “Unsafe at any Key Size” presented in October 2000 802.11 Task Group I formed to solve WEP security problems Press gets wind of the issue Public domain attacks; “war driving”

35. EE579T/GD_6 #35 Summer 2003 © 2000-2003, Richard A. Stanley WEP Security Problems (cont.) Passive attacks to decrypt traffic based on statistical analysis Active ‘known plaintext’ attack to inject new traffic from unauthorized mobile stations Active attacks to decrypt traffic, based on tricking the access point Dictionary-building attack; real-time automated decryption of all traffic after a day’s sampling

36. EE579T/GD_6 #36 Summer 2003 © 2000-2003, Richard A. Stanley Wardriving Sample

37. EE579T/GD_6 #37 Summer 2003 © 2000-2003, Richard A. Stanley The Threat: A Sampler of WLAN Hacker Tools Courtesy AirDefense

38. EE579T/GD_6 #38 Summer 2003 © 2000-2003, Richard A. Stanley 802.11 Task Group I Long term security architecture for 802.11 Based on 802.1X authentication standard and two new encryption protocols (TKIP and CCMP) – Labeled Robust Security Network (RSN) Uses Upper Layer Authentication (ULA) protocols outside the scope of 802.11i (e.g. EAP/TLS)

39. EE579T/GD_6 #39 Summer 2003 © 2000-2003, Richard A. Stanley RSN Data Privacy Protocols Temporal Key Integrity Protocol (TKIP) –a cipher suite enhancing the WEP protocol on pre-RSN hardware Counter Mode/CBC-MAC Protocol –based on AES and Counter-Mode/CBC-MAC (CCM) –Mandatory for RSN compliance

40. EE579T/GD_6 #40 Summer 2003 © 2000-2003, Richard A. Stanley Robust Security Network Includes: Better key derivation/distribution based on 802.1X –For TKIP: per message 128 bit key derivation Improved encryption (TKIP, CCMP) Stronger keyed Message Integrity Checks –Custom MIC for TKIP with 22 bit effective strength –Strong AES-based MIC for CCMP IV sequencing to control message replay –44 bits to avoid re-keying (4 bits for QoS)

41. EE579T/GD_6 #41 Summer 2003 © 2000-2003, Richard A. Stanley 802.1X Originally designed as port-based network access control for PPP Provides support for a centralized management model Primary encryption keys are unique to each station and generated dynamically Provides support for strong upper layer authentication (ULA)

42. EE579T/GD_6 #42 Summer 2003 © 2000-2003, Richard A. Stanley 802.1X Architectural Framework Employs Extensible Authentication Protocol (EAP) –EAP built around challenge-response paradigm –operates at network layer = flexibility Provides transport for ULA protocols Two sets of keys dynamically generated –Session Keys, Group Keys

43. EE579T/GD_6 #43 Summer 2003 © 2000-2003, Richard A. Stanley 802.1X Overview Generic method for Port Based Network Access and Authentication for IEEE 802 LAN’s Specifies protocol between devices (wireless clients) desiring access to the bridged LAN and devices (Access Points) providing access to the bridged LAN Specifies the protocol between the authentication server (e.g. RADIUS) and the authenticator Specifies different levels of access control Specifies the behavior of the port providing access to the LAN

44. EE579T/GD_6 #44 Summer 2003 © 2000-2003, Richard A. Stanley 802.1x Definitions Authenticator : System port that is responsible for granting access to services that are accessible via the port (e.g. AP) Supplicant : The port requesting access to the service via the authenticator (e.g. wireless client) Port Access Entity: The software that is associated with the port. It supports the functionality of Authenticator, Supplicant or both Authentication Server: An entity that provides the authentication service to the authenticator. Usually an external or remote server (e.g. RADIUS)

45. EE579T/GD_6 #45 Summer 2003 © 2000-2003, Richard A. Stanley

46. EE579T/GD_6 #46 Summer 2003 © 2000-2003, Richard A. Stanley Description cont. IEEE 802.1X Terminology Controlled port Uncontrolled port SupplicantAuthentication ServerAuthenticator Pieces of the system.

47. EE579T/GD_6 #47 Summer 2003 © 2000-2003, Richard A. Stanley Normal Data Blocked Authentication traffic flows Wireless laptopAuthentication ServerAccess Point 802.1X trafficAuthentication traffic Normal Data Initially Blocked by Access Point Wireless client associates with the AP Only Authentication Traffic is allowed to flow through Access Point The Access Point Blocks all Normal Data Traffic Access point correctly encapsulates the 802.1x traffic and Authentication Traffic

48. EE579T/GD_6 #48 Summer 2003 © 2000-2003, Richard A. Stanley Wireless laptop (Supplicant) Authentication ServerAccess Point (Authenticator) 802.1X trafficAuthentication traffic Mutual Authentication The Supplicant securely obtains the WEP key during Proper Authentication The RADIUS Server sends the WEP Key to the Access Point The WEP Key is then used by the Access Point to send the Broadcast WEP key Normal Data Traffic is still blocked Only Authentication Traffic is passed by the AP

49. EE579T/GD_6 #49 Summer 2003 © 2000-2003, Richard A. Stanley Wireless laptop (Supplicant) Authentication ServerAccess Point (Authenticator) 802.1X trafficAuthentication traffic Client Access Granted The client decrypts the broadcast key using the session WEP key The client sets the broadcast WEP key through the NIC interface Successful EAP Authentication Normal Data traffic is now enabled Authentication traffic flows Data traffic flows

50. EE579T/GD_6 #50 Summer 2003 © 2000-2003, Richard A. Stanley Wireless laptop (Supplicant) Authentication ServerAccess Point (Authenticator) 802.1X trafficAuthentication traffic New Authentication Types Only Authentication server is aware of the authentication type, e.g. - Kerberos - One Time Password Client and AP need not be modified to add new authentication types

51. EE579T/GD_6 #51 Summer 2003 © 2000-2003, Richard A. Stanley Key Distribution Dynamic Session Key - Session key depends on EAP authentication type - The client specific session key is sent to the AP from the RADIUS Broadcast Key - The Dynamic session Key is used to encrypt the broadcast key sent from the AP to the wireless client - Authentication server timeouts can be configured to re-authenticate the client (adds extra security)

52. EE579T/GD_6 #52 Summer 2003 © 2000-2003, Richard A. Stanley Client-AP Implementation Client (Supplicant) - Prior to 802.1x authentication, the client-AP use an open authentication model - On authentication, dynamic WEP is used - Both the client and AP must be able to support WEP and non- WEP traffic Access Point (Authenticator) - Communicates with the client using 802.1x - Communicates with the Authentication Server using RADIUS - Encapsulates incoming EAPOL traffic into RADIUS traffic

53. EE579T/GD_6 #53 Summer 2003 © 2000-2003, Richard A. Stanley Drawbacks EAPOL traffic for Shared-Media LANS means that WLANs should be encrypted. Encryption of EAPOL not mandatory in 802.1x Port Based Network access defined only for “Infrastructure Mode” of WLANs. Peer-to- peer (Ad Hoc) mode not dealt with.

54. EE579T/GD_6 #54 Summer 2003 © 2000-2003, Richard A. Stanley EAP Summary EAP is an end-to-end security solution –Mitigates the current WLAN security threats of stolen hardware and rogue access points. –User-specific session-based WEP keys used. Reduces risk of static WEP keys lying around on clients and APs –Replaces currently deployed Static WEP with a more secure Dynamic WEP key distribution mechanism –Centralized authentication and access model via the RADIUS server

55. EE579T/GD_6 #55 Summer 2003 © 2000-2003, Richard A. Stanley 802.11i - Summary Draft provides a system to greatly enhance security for users of Wi-Fi equipment Improved encryption and 802.1X standard for authentication – address all the shortfalls in the current standard Draft standard expected to be ratified in fall of 2003

56. EE579T/GD_6 #56 Summer 2003 © 2000-2003, Richard A. Stanley Issues 802.11i draft standard exists on paper, but compliance cannot be claimed before ratification Solution required now Current proprietary solutions do not interoperate

57. EE579T/GD_6 #57 Summer 2003 © 2000-2003, Richard A. Stanley Existing Solutions & Other Methods MAC address filtering Access Point Placement Proprietary Solutions –Cisco’s LEAP –NextComm’s Key Hopping –3Com’s Embedded firewall in wireless APs Virtual Private Networks (VPNs)

58. EE579T/GD_6 #58 Summer 2003 © 2000-2003, Richard A. Stanley Wi-Fi Protected Access - WPA WPA is a response by the industry to offer strong and immediate security solution that would replace WEP It is a subset of 802.11i draft standard and is going to maintain forward compatibility Main idea - “Bring what is ready now to the market” Increases the level of security for Wireless LAN It is a standards-based, interoperable security specification

59. EE579T/GD_6 #59 Summer 2003 © 2000-2003, Richard A. Stanley WPA Provides user authentication –Central authentication server (like RADIUS) –Via 802.1x and EAP Improves data encryption –Temporal Key Integrity Protocol (TKIP) Eventually will support full 802.11i compliance Some implementation issues remain

60. EE579T/GD_6 #60 Summer 2003 © 2000-2003, Richard A. Stanley Best Practices For Now WEP is better than nothing; turn it on and change keys often Engineer placement of access points Upgrade firmware and drivers on APs and wireless cards as they are released VPN (treat wireless users as you would dial-in users) –No panacea, but much better than nothing Check for 802.1x support before buying

61. EE579T/GD_6 #61 Summer 2003 © 2000-2003, Richard A. Stanley The Future Improved encryption and authentication –Part of 802.11i standard –Likely to be deployed soon (2004?) –Major problems with installed base Increased user sensitivity to security issues driving demand for solutions Products entering the marketplace to automatically identify vulnerabilities