1. EE579T/11 #1 Spring 2005 © 2000-2005, Richard A. Stanley EE579T / CS525T Network Security 11: Intrusion Detection Systems; Wireless Security Prof. Richard A. Stanley

2. EE579T/11 #2 Spring 2005 © 2000-2005, Richard A. Stanley Overview of Tonight’s Class Review last week’s lesson Final Exam –On the web page –Due to me electronically in 2 weeks (26 Apr) Project Scheduling –Presentations on 15 April –Keep presentations to 25 minutes including Q&A –Let’s have volunteers for each time slot, keeping in mind your work schedules Intrusion detection systems Wireless security

3. EE579T/11 #3 Spring 2005 © 2000-2005, Richard A. Stanley 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!

4. EE579T/11 #4 Spring 2005 © 2000-2005, Richard A. Stanley Intrusion Detection Systems Oddly enough, these are systems designed to detect intrusions into protected systems Security intrusion (per RFC 2828): –A security event, or a combination of multiple security events, that constitutes a security incident in which an intruder gains, or attempts to gain, access to a system (or system resource) without having authorization to do so.

5. EE579T/11 #5 Spring 2005 © 2000-2005, Richard A. Stanley What’s a Security Incident? A security event that involves a security violation. (See: CERT, GRIP, security event, security intrusion, security violation.) In other words, a security-relevant system event in which the system's security policy is disobeyed or otherwise breached. "Any adverse event which compromises some aspect of computer or network security." [R2350] Source: RFC 2828, page 152; emphasis added

6. EE579T/11 #6 Spring 2005 © 2000-2005, Richard A. Stanley Why Do We Need This? With the exception of authentication systems, most of the defenses we have studied up to now are directed towards intruders coming from outside the firewall These systems are not perfect--some intruders will get through Moreover, defenses such as firewalls cannot protect against intruders on the inside

7. EE579T/11 #7 Spring 2005 © 2000-2005, Richard A. Stanley Intrusion Detection Functions Monitor protected networks and computers in real time (or as close to real time as is practicable) Detect security incidents –Requires a policy, and a way for the IDS to know what that policy is Respond –Raise an alarm –Send some automated response to the attacker

8. EE579T/11 #8 Spring 2005 © 2000-2005, Richard A. Stanley IDS vs. Auditing Audits tend to be a posteriori –But an IDS can be seen as performing a constant, near real time audit function To perform an audit, you need to know what the policy is –Audits measure departures from the policy norms –Audits depend on system logs

9. EE579T/11 #9 Spring 2005 © 2000-2005, Richard A. Stanley Early IDS’s Emulated the audit function –Crawled the logs, looking for deviations from policy-permitted actions –Intent was to speed up the audit, making it nearly real time –Still a useful approach IDS technology has been around only since the early 1990’s; not too mature

10. EE579T/11 #10 Spring 2005 © 2000-2005, Richard A. Stanley IDS Uses Monitor system usage –Determine access, usage patterns –Plan for capacity engineering Monitor specific problem areas Serve as a deterrent –Sort of like the “burglar alarm” label on a house, even if there is really no alarm

11. EE579T/11 #11 Spring 2005 © 2000-2005, Richard A. Stanley Log Files Are evidence if an intrusion occurs –Must be stored in their original, unmodified form, otherwise inadmissible in court –Provide data from which trends can be deduced –Can be subjected to forensic analysis –Probably needed to assess level of system compromise/damage and to restore to state prior to intrusion

12. EE579T/11 #12 Spring 2005 © 2000-2005, Richard A. Stanley Legal Issues - 1 Privacy of your employees –Courts have held that employees have little expectation of privacy in the workplace, especially if told so at the outset email can be monitored at work by employer phone calls can be monitored at work by employer doing either of these things outside the workplace violates the wiretap statutes (18 USC § 2516, etc.)

13. EE579T/11 #13 Spring 2005 © 2000-2005, Richard A. Stanley Legal Issues - 2 What if the IDS discovers illegal acts being performed on/by your network? –Employees using the network for illegal activities –Outsiders having planted zombie programs so that your system attacks others –What is your responsibility and liability?

14. EE579T/11 #14 Spring 2005 © 2000-2005, Richard A. Stanley Legal Issues - 3 This may be a Catch-22 issue –If an attacker is using your system, law enforcement may want you to continue to allow that to happen so they can apprehend the attacker If you interrupt the attack, could be interpreted as obstruction of justice –But, if you allow the attack to continue, you may be liable for damages to those attacked Get legal advice--beforehand!

15. EE579T/11 #15 Spring 2005 © 2000-2005, Richard A. Stanley What About Automated Response? Tempting capability If attacking your system is illegal, what makes your attack on the attacker in response less illegal? What if you are, or are acting on behalf of, a governmental entity and the attacker is also a governmental entity? –Casus belli

16. EE579T/11 #16 Spring 2005 © 2000-2005, Richard A. Stanley IDS Architecture Sensor Management Console

17. EE579T/11 #17 Spring 2005 © 2000-2005, Richard A. Stanley Console Monitors and controls sensors –Sets policy, alarm levels, etc. –Stores logs Must have secure communications with sensors –Encrypted connection –Out of band (OOB)

18. EE579T/11 #18 Spring 2005 © 2000-2005, Richard A. Stanley IDS Types Network-based (NIDS) –Monitors the network backbone Network node-based (NNIDS) –Monitors network nodes, not the backbone Host-based (HIDS) –This is the “log crawler” that started it all Gateway (GIDS) –NIDS in series with the network

19. EE579T/11 #19 Spring 2005 © 2000-2005, Richard A. Stanley What Can It See? Network packets OS API calls System logs How do we merge this data to detect intrusions?

20. EE579T/11 #20 Spring 2005 © 2000-2005, Richard A. Stanley Host-Based Sits on a host as a background task Monitors (potentially) –traffic to and from the host –OS API calls –system logs Adds to processing load on the host, so host must be able to support the extra load

21. EE579T/11 #21 Spring 2005 © 2000-2005, Richard A. Stanley Network-based NIDS sensors placed on network backbone –Can view only packet traffic passing by, much like a classic passive sniffer –Does not place processing load on network, but the NIDS platform must be capable of dealing with network traffic speeds Software can usually handle  100 Mbps Hardware only 2-3 times faster If network is faster, looks only at subset of packets

22. EE579T/11 #22 Spring 2005 © 2000-2005, Richard A. Stanley Network Node-based Used to inspect intrusions directly into network nodes –Effectively a blending of HIDS and NIDS –Used to protect mission-critical machines –Again, a background process on existing nodes, so node must be able to handle added processing load

23. EE579T/11 #23 Spring 2005 © 2000-2005, Richard A. Stanley Gateway In series with network –Often set to block prohibited traffic automatically –Think of it as an in-network firewall with an extended rule set –Must be able to keep up with network load

24. EE579T/11 #24 Spring 2005 © 2000-2005, Richard A. Stanley Intrusion Protection Systems Latest trend in IDS technology Idea is to use what the IDS identifies to change the network rules ad hoc, in theory preventing further exploitation Very similar to GIDS

25. EE579T/11 #25 Spring 2005 © 2000-2005, Richard A. Stanley IPS Issues Attack signatures generally known only a posteriori Heuristic analysis has not worked very well in other venues, such as virus detection How long to maintain the “new” rules before reverting to the original ones? Exploitation of the IPS

26. EE579T/11 #26 Spring 2005 © 2000-2005, Richard A. Stanley Deployment Putting in an IDS is a complex and time- consuming affair –Typically, start simple and add functionality as you learn more about the network –NIDS tends to see more and load network least –Follow up with HIDS on selected hosts, perhaps NNIDS on critical nodes Policy has to be in place first

27. EE579T/11 #27 Spring 2005 © 2000-2005, Richard A. Stanley Attack Signatures Critical to success of any IDS Must be maintained, just like virus signatures –You want some visibility into this –Do you want strangers deciding what is an attack on your critical systems? Some IDS’s let you write/modify signatures, others do not CVE: http://www.cve.mitre.org/http://www.cve.mitre.org/

28. EE579T/11 #28 Spring 2005 © 2000-2005, Richard A. Stanley IDS Deployment First, design the IDS sensor and management layout Next, deploy the IDS –Test the network for normal operation –Test the IDS Run packaged attacks to see if all are detected Document performance and repeat test regularly –Tune the IDS

29. EE579T/11 #29 Spring 2005 © 2000-2005, Richard A. Stanley Sampling of IDS Products RealSecure: http://www.iss.net/products_services/enterp rise_protection/rsnetwork/sensor.php http://www.iss.net/products_services/enterp rise_protection/rsnetwork/sensor.php NFR: http://www.nfr.net/http://www.nfr.net/ Snort: http://www.snort.org/http://www.snort.org/ SnortSnarf: http://www.silicondefense.com/software/sn ortsnarf/ http://www.silicondefense.com/software/sn ortsnarf/

30. EE579T/11 #30 Spring 2005 © 2000-2005, 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

31. EE579T/11 #31 Spring 2005 © 2000-2005, Richard A. Stanley Wireless Network Security Wireless networks growing at a rapid pace –Gartner Group predicts wireless installations will multiply >7X by 2007 to over 31M Business drivers –Installation cost and time –Mobility –Flexibility –Operating costs

32. EE579T/11 #32 Spring 2005 © 2000-2005, Richard A. Stanley Wireless Inherently Insecure Wired networks contain (or try) signals to a wired path, which must be physically tapped to compromise line security –Possible to physically discover the tap Wireless networks deliberately broadcast data into space, where it can be intercepted by anyone with proper receiver –Data tap impossible to discover

33. EE579T/11 #33 Spring 2005 © 2000-2005, Richard A. Stanley This Isn’t New News Since early days, wireless vendors strove to provide privacy equivalent to that available on the wired network –WEP = wired equivalent privacy –This is not a high standard to meet They succeeded, but that wasn’t good enough for user requirements

34. EE579T/11 #34 Spring 2005 © 2000-2005, Richard A. Stanley Wireless Security Issues How does a wireless network work? How can you “join up?” What about the encryption? Can it really be secure?

35. EE579T/11 #35 Spring 2005 © 2000-2005, Richard A. Stanley How It Works Clients send probes Access points broadcast beacons and, often, their Server Set ID (SSID) When a client finds an access point with an acceptable signal level and a matching SSID, a connection is established Many networks are built precisely to facilitate connection by “foreign” users

36. EE579T/11 #36 Spring 2005 © 2000-2005, Richard A. Stanley Wireless LAN Elements [AP] [STA]

37. EE579T/11 #37 Spring 2005 © 2000-2005, 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. –NSA only allowed 40-bit encryption to be exported.

38. EE579T/11 #38 Spring 2005 © 2000-2005, 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.

39. EE579T/11 #39 Spring 2005 © 2000-2005, 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.

40. EE579T/11 #40 Spring 2005 © 2000-2005, Richard A. Stanley WEP Encryption + Initialization Vector (IV) Secret Key Plaintext + Seed PRNG RC4() Ciphertext Cache Key Sequence (MAX_MSG_SZ) IV

41. EE579T/11 #41 Spring 2005 © 2000-2005, Richard A. Stanley IEEE 802.11’s use of WEP IEEE runs by Robert’s Rules; “one man, one vote” Simple majority required to add text, 75% vote to change text in draft standard WEP introduced in March 1994 Strong pushback in committee regarding cost and overhead of encryption Dilution of proposal; privacy made optional

42. EE579T/11 #42 Spring 2005 © 2000-2005, 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”

43. EE579T/11 #43 Spring 2005 © 2000-2005, 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

44. EE579T/11 #44 Spring 2005 © 2000-2005, 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, PEAP)

45. EE579T/11 #45 Spring 2005 © 2000-2005, 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)

46. EE579T/11 #46 Spring 2005 © 2000-2005, 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

47. EE579T/11 #47 Spring 2005 © 2000-2005, 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

48. EE579T/11 #48 Spring 2005 © 2000-2005, 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 – EAP/TLS, PEAP, EAP-TTLS, LEAP Two sets of keys dynamically generated –Session Keys, Group Keys

49. EE579T/11 #49 Spring 2005 © 2000-2005, Richard A. Stanley Authentication and Key Mgmt. EAP Wired LAN Services Unauthorized Port Controlled Port STA AP AS Uncontrolled Port EAPoLRADIUS Supplicant Authenticator Authentication Server EAP

50. EE579T/11 #50 Spring 2005 © 2000-2005, Richard A. Stanley Existing Solutions & Other Methods MAC address filtering Access Point Placement Virtual Private Networks (VPNs)

51. EE579T/11 #51 Spring 2005 © 2000-2005, Richard A. Stanley Enter The Wi-Fi Alliance Wi-Fi Alliance – nonprofit International association formed in 1999 176 member companies as of today Mission: Certify interoperability of Wireless LAN products based on IEEE 802.11 specification

52. EE579T/11 #52 Spring 2005 © 2000-2005, 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

53. EE579T/11 #53 Spring 2005 © 2000-2005, 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

54. EE579T/11 #54 Spring 2005 © 2000-2005, Richard A. Stanley 802.11i Status? Many devices fielded since 2003 have silicon implementations in them to support full 802.11i –Supports AES –Other features –Firmware updates should turn on features Standard ratified in late 2004

55. EE579T/11 #55 Spring 2005 © 2000-2005, Richard A. Stanley NetStumbler

56. EE579T/11 #56 Spring 2005 © 2000-2005, Richard A. Stanley Exploitation Tools Wardriving: http://www.wardriving.com/http://www.wardriving.com/ Warchalking: http://www.warchalking.org/http://www.warchalking.org/ Airsnort: http://airsnort.shmoo.com/http://airsnort.shmoo.com/ WEPCrack: http://wepcrack.sourceforge.net/ http://wepcrack.sourceforge.net/ What other little “gifts” await us?

57. EE579T/11 #57 Spring 2005 © 2000-2005, Richard A. Stanley Best Practice for now WEP is better than nothing; change keys often Physical 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) Check for 802.1x support before buying

58. EE579T/11 #58 Spring 2005 © 2000-2005, Richard A. Stanley Wireless Security Summary It’s a problem, owing to the nature of wireless transmission So far, security implementations have left a lot to be desired Project presentations will provide added details Growth is explosive, both in legitimate and illegitimate wireless activity