1 Wireless Security Update Mark Ciampa Western Kentucky University

2 Oxymoron Government organization Same difference Pretty ugly Working vacation Tax return

3 Oxymoron Jumbo shrimp Adult male Act naturally Microsoft Works Wireless security

4 Wireless Advantages Mobility Increased productivity Easier installation Less expensive installation

5 Wireless Disadvantages Radio signal interference Health risks Security

6 Wireless Security Vulnerabilities Unauthorized users access the wireless network Attackers view transmitted data Employees install rogue access points Weaknesses in original IEEE wireless security and new WPA

7 Wireless Attack Tools NetStumbler – Discover wireless network Airopeek & Airmagnet – Packet sniffers Kismet & Airsnort – Break security

8 Wireless Security Attitudes “ It doesn’t matter if someone uses my wireless LAN” “You can’t make a wireless LAN secure” “I don’t know what to do”

9 Does Wireless Security Matter? Get into any folder set with file sharing enabled See wireless transmissions Access to network behind firewall can inject malware Download harmful content linked to unsuspecting owner

10 Does Wireless Security Matter? Legal implications Security begins at home

11 Can Make Wireless Secure Significant improvement wireless security New IEEE wireless standard ratified Common non-technical wireless security language now used Vendors making wireless security easier

12 Wireless Security Update Wireless security that doesn’t work and why Wireless security that does work How to secure a home WLAN Contents of wireless curriculum How to secure an enterprise WLAN

13 Wireless Security Update WLAN Defenses That Do Not Work

14 Common WLAN Defenses Encrypt transmissions (WEP) Hide my network (Disable SSID beaconing) Restrict who can join my network (MAC address filtering) Use advanced security (WPA)*

15 WLAN Defenses That Don’t Work Encrypt transmissions (WEP) Hide my network (Disable SSID beaconing) Restrict who can join my network (MAC address filtering) Use advanced security (WPA)*

16 WEP Wired equivalent privacy (WEP) intended to guard confidentiality of data through cryptography WEP relies on a secret key that is “shared” between device and access point (AP) Using same (shared) secret key to both encrypt and decrypt is private key cryptography or symmetric encryption

17 WEP Objectives Efficient - Algorithm must be proficient enough to be implemented in either hardware or software Exportable - Must meet the guidelines set by the U.S. Department of Commence so wireless device using WEP can be exported overseas Optional - The implementation of WEP in wireless LANs is an optional feature

18 WEP Objectives Reasonably strong - Security of the algorithm lies in the difficulty of determining the secret keys through attacks, which is related to the length of the secret key and the frequency of changing keys. WEP was to be “reasonably” strong in resisting attacks. Self-synchronizing - Each packet must be separately encrypted (prevents a single lost packet from making subsequent packets indecipherable)

19 WEP Keys WEP keys must be a minimum of 64 bits in length Most vendors add an option to use a larger 128-bit WEP key for added security (a longer key is more difficult to break)

20 WEP Key Creation 64-bit WEP key created by entering 5 ASCII characters (5y7js) or 10 hexadecimal characters (456789ABCD) 128-bit WEP key created by entering 13 ASCII characters (98jui2wss35u4) or 26 hexadecimal characters ( AABBCCDDEE) Passphrase created by entering 16 ASCII characters (marchspringbreak)

21 How WEP Works 1. Information has cyclic redundancy check (CRC) checksum value calculated (WEP calls this integrity check value (ICV)) and appends it to end of text 2. WEP default shared secret key combined with initialization vector (IV), a 24-bit value that changes each time a packet is encrypted

22 How WEP Works

23 How WEP Works 3. Default shared secret key and IV are then entered into an RC4 pseudo- random number generator (PRNG) that creates a random number (output is keystream) 4. Text + ICV and keystream combined through exclusive OR (XOR) to create ciphertext 5. IV pre-pended to ciphertext

24 How WEP Works

25 WEP Won’t Work WEP creates a detectable pattern for attackers (weak keys) Attacker who captures packets for length of time can see the duplication and use it to crack the code Weakness is with initialization vector (IV), 24-bit value that changes each time a packet is encrypted

26 WEP Won’t Work IV is 24-bit number = 16,777,216 possible values “Expanded” WEP not increase IV AP transmitting at only 11 Mbps can send and receive 700 packets each second Since different IV used for each packet IVs start repeating in less than 7 hours Ways to reduce time needed to minutes Some WLANs always start with the same IV after the system is restarted and then follow the same sequence of incrementing IVs

27 WEP Won’t Work RC4 uses a pseudo-random number generator (PRNG) to create keystream PRNG does not create true random number but what appears to be (pseudo) random number First 256 bytes of the RC4 cipher can be determined by bytes in the key itself RC4 cipher is not considered the most effective cipher for the task

28 WLAN Defenses That Don’t Work Encrypt transmissions (WEP) Hide my network (Disable SSID beaconing) Restrict who can join my network (MAC address filtering) Use advanced security (WPA)*

29 SSID Beaconing Service Set Identifier (SSID) is “beaconed” from AP Provides information to wireless devices wanting to join network Beaconing SSID is default mode Some users disable SSID beaconing so network not appear on Windows list of available wireless networks

30 Disable SSID Beaconing

31 Disable SSID Beaconing Won’t Work SSID is initially transmitted in cleartext when device negotiating with AP Attacker only has to watch for any authorized device to negotiate If attacker cannot capture initial negotiation process can force one to occur

32 Force Renegotiation

33 Disable SSID Beaconing Won’t Work If SSID suppressed from beacon frames, still transmitted in other management frames sent by the AP Windows can’t see it Netstumbler can see it Many users do not change default SSID and these well known; an attacker can try default SSIDs until a connection is accepted

34 Disable SSID Beaconing Won’t Work Steps to manually enter SSID on wireless device that not receive beaconed SSID are inconvenient Turning off SSID beaconing prevents wireless devices from freely roaming from one wireless network to another Many access points prohibit or discourage turning off SSID beaconing

35 Discourage Turning Off SSID Beaconing

36 Disable SSID Beaconing Won’t Work Not uncommon to detect multiple wireless signals at home or work May received signal with broadcast SSID and signal where broadcast SSID turned off If using Windows XP the device will always connect to the access point that is broadcasting its SSID

37 WLAN Defenses That Don’t Work Encrypt transmissions (WEP) Hide my network (Disable SSID beaconing) Restrict who can join my network (MAC address filtering) Use advanced security (WPA)*

38 MAC Address Filtering Access control - Intended to limit a user’s admission to the AP (only those authorized able to become part of wireless LAN) Most common type of access control is Media Access Control (MAC) address filtering (not part IEEE standard) MAC address is unique 48-bit number “burned” into the network interface card adapter when manufactured

39 MAC Address

40 MAC Address

41 MAC Address Filtering Access to the wireless network can be restricted by entering the MAC address of approved or denied devices Once the MAC addresses are entered, only specific devices can be authenticated based on MAC address

42 MAC Address Filtering

43 MAC Filtering

44 MAC Address Filtering Won’t Work MAC addresses initially exchanged in cleartext between device and access point MAC address can be “spoofed” Some wireless NICs allow for a substitute MAC address to be used Programs available that allow users to spoof MAC address

45 MAC Address Filtering Won’t Work

46 WLAN Defenses That Don’t Work Encrypt transmissions (WEP) Hide my network (Disable SSID beaconing) Restrict who can join my network (MAC address filtering) Use advanced security (WPA)*

47 WPA Won’t Work* Wi-Fi Protected Access (WPA) Intended to provide enhanced security using older wireless equipment Must enter same passphrase on access point and wireless device Passphrases less than 20 characters subject to offline dictionary attacks

48 Wireless Security Update Wireless Security Solutions

i By IEEE organization Designed specifically address WLAN vulnerabilities Ratified June 2004

50 Common Security Models By Wi-Fi organization Personal Security Model WPA – Personal WPA2 - Personal Enterprise Security Model WPA - Enterprise WPA2 - Enterprise

51 Wireless Security Update Personal Security Model - WPA

52 Personal Security Model Designed for single users or small office home office (SOHO) settings of < 10 devices and authentication server unavailable Personal security model has 2 options WPA – Legacy hardware WPA2 – Newer hardware

53 Wi-Fi Protected Access (WPA) Wi-Fi Alliance introduced Wi-Fi Protected Access (WPA) in October 2003 Subset of i Addresses encryption & authentication Designed to enhance security on older WLAN devices

54 Temporal Key Integrity Protocol (TKIP) WPA replaces WEP with new encryption Temporal Key Integrity Protocol (TKIP) TKIP uses 128-bit per-packet key (dynamically generates a new key for each packet and prevents collisions) TKIP distributes key to client and AP, setting up automated key hierarchy and management system TKIP dynamically generates unique keys to encrypt every data packet

55 TKIP Encryption TKIP strong substitution WEP encryption Instead of replacing WEP engine TKIP designed to fit into the existing WEP procedure with a minimal amount of change Device starts with 2 keys, a 128-bit encryption key (temporal key) and 64-bit MIC

56 TKIP Encryption 1. Temporal key XORed with sender’s MAC address to create an intermediate Value 1 2. Value 1 then mixed with a sequence number to produce Value 2 (the per-packet key) and then entered into the (PRNG), just as with normal WEP 3. Sender’s MAC address and receiver’s MAC address are all run through a MIC function and creates text with MIC key appended; value is then XORed with keystream to create ciphertext

57 TKIP Encryption

58 TKIP Key Mixing WEP constructs a per-packet RC4 key by concatenating a key and packet IV TKIP per-packet key construction (TKIP key mixing) substitutes temporary (temporal) key for WEP base key and constructs a per-packet key that changes with each packet Temporal keys have fixed lifetime and are replaced frequently

59 IV Sequencing TKIP reuses the WEP IV field as a sequence number for each packet Both the transmitter and receiver initialize the packet sequence space to zero whenever new TKIP keys are set, and the transmitter increments the sequence number with each packet it sends Length of the sequence number (IV) has been doubled, from 24 bits to 48 bits.

60 Message Integrity Check (MIC) WPA replaces Cyclic Redundancy Check (CRC) with Message Integrity Check (MIC), designed to prevent an attacker from altering packets Attacker can modify a packet and the CRC, making it appear that the packet contents were the original Receiver and transmitter each compute and then compare the MIC If not match, the data is assumed to have been tampered with and the packet is dropped Optional countermeasure all clients are de- authenticated and new associations are prevented for one minute if MIC error occurs

61 Pre-Shared Key (PSK) Authentication WPA authentication can be accomplished by either authentication server or pre-shared key (PSK) Passphrase (the PSK) is manually entered to generate encryption key on AP and devices in advance PSK not used for encryption but instead serves as the starting point (seed) for generating the encryption keys Disadvantage of key management: key must be created and entered in any device (“shared”) prior to (“pre”) communicating

62 Wi-Fi Protected Access (WPA) Designed to enhance security on older WLAN devices Should only be used if devices cannot support WPA2

63 Personal Security Model

64 Wireless Security Update Personal Security Model – WPA2

65 Wi-Fi Protected Access 2 (WPA2) Wi-Fi Alliance introduced Wi-Fi Protected Access 2 (WPA2) in September 2004 WPA2 based on the final IEEE i WPA2 uses AES for data encryption and supports authentication server or PSK technology WPA2 allows both AES and TKIP clients to operate in the same WLAN; IEEE i only recognizes AES

66 AES AES algorithm processes blocks of 128 bits, yet the length of the cipher keys and number of rounds can vary, depending upon the level of security that is required Available key lengths are of 128, 192 and 256 bits, and the number of available rounds are 10, 12, and 14 Only the 128-bit key and 128-bit block are mandatory for WPA2 It is recommended that AES encryption and decryption be performed in hardware because of the computationally intensive nature of AES

67 AES Security

68 Personal Security Model

69 Wireless Security Update How To Make a Home Wireless LAN Secure

70 Steps Protect Personal Wireless Install Microsoft Hot Fix (KB893357) Turn on WPA2 On older equipment use WPA MUST use 20+ character WPA passphrase Turn on wireless VLAN If want to deter “casual” users Use MAC address filtering Use unidentifiable SSID Turn off SSID beaconing

71 Set WPA2 on AP

72 Set WPA2 on AP

73 Set WPA2 on Device

74 Show WPA2

75 Turn on VLAN

76 Secure Easy Setup Collaboration between Linksys and Broadcom Activate WPA security “at the push of a button” Automatically configures custom SSID and enables WPA dynamic key encryption settings No need to manually enter a passphrase or key Two step process Push the SES button on access point Click the START SES button on client To add more wireless devices to network simply push the button on the router again to repeat process

77 Secure Easy Setup

78 Wireless Security Update Contents of Wireless Curriculum

79 Wireless Curriculum CompTIA dropped proposed Wireless+ certification Most popular wireless certifications from CWNA (Planet3) Wireless# Certified Wireless Network Administrator Certified Network Security Professional

80 Course Technology Wireless Textbooks Guide to Wireless Communications 2ed (Wireless#) – May 2006 CWNA Guide to Wireless LANs 2ed (CWNA) – August 2005 CWSP Guide to Wireless Security 1 st (CWSP) – August 2006

81 Wireless Security Update Enterprise Security Model – WPA & WPA2

82 Enterprise Security Model Designed for medium to large-size organizations such as businesses, government agencies, and universities with authentication server The personal security model has 2 options: WPA & WPA2 (older equipment may be forced to implement WPA, while newer equipment can support WPA2)

x IEEE i authentication and key management uses IEEE 802.1x (originally developed for wired networks) 802.1x port security (device requests access to network prevented from receiving any traffic until its identity can be verified) 802.1x blocks all traffic on port-by-port basis until the client is authenticated using credentials stored on authentication server

x Authentication The supplicant is device which requires secure network access and sends request to an authenticator that serves as an intermediary device (authenticator can be an access point on a wireless network or a switch on a wired network) The authenticator sends request from supplicant to authentication server, which accepts/rejects the supplicant’s request and sends that information back to the authenticator, which in turn grants or denies access to the supplicant Strength of the 802.1x protocol is that supplicant never has direct communication with authentication server

x 1. Device requests from AP permission to join WLAN 2. AP asks device to verify its identity 3. Device sends identity information to AP, which passes encrypted information to authentication server 4. Authentication server verifies/rejects client’s identity and returns information to AP 5. Approved client now join the network

x

x Supplicant Supplicant, required on the wireless device, is software that is installed on the client to implement the IEEE 802.1x protocol framework Supplicant software may be included in client operating system, integrated into device drivers, or installed as third-party “standalone” software Some vendors of wireless NICs supply supplicant with their cards

88 Authentication Server Authentication server stores the list of the names and credentials of authorized users Wireless user credentials may also be stored in an external database, such as Structured Query Language (SQL), Lightweight Directory Access Protocol (LDAP), or Microsoft Active Directory Typically a Remote Authentication Dial- In User Service (RADIUS) server is used

89 RADIUS Request is first sent to authenticator, which relays the information (username, password, type of connection) to RADIUS server Server first determines if AP itself is permitted to send requests RADIUS server attempts to find the user’s name in its database Then applies the password to decide whether access should be granted to this user

90 Encryption Once authenticated by IEEE 802.1x same protocol next provides the wireless device a unique encryption key called the MK From single key all the necessary encryption keys for encrypted communication can then be created Keys can also be changed during a session

91 Encryption Eliminates difficulties and potential dangers associated with PSK Each user has a unique key Keys remain strong and require no management Adding additional APs only requires that the newly installed APs connect to the existing authentication server

92 Extensible Authentication Protocol (EAP) EAP-Transport Layer Security (EAP-TLS) - Requires the use of certificates to validate a supplicant and supported by Microsoft and included in Microsoft Windows XP and Windows Server 2003 Lightweight EAP (LEAP) - Propriety standard supported by Cisco; LEAP provides authentication based on the Windows username and password logon (certificates are not required) EAP-TunneledTLS (EAP-TTLS) - Supports advanced authentication methods such as using tokens Protected EAP (PEAP) - Uses certificates similar to Secure Sockets Layer (SSL) with Web browsers; supplicant presents a certificate to the authentication server (via the authenticator) but does not require a certificate from the server in return Flexible Authentication via Secure Tunneling (FAST) - Most recent variation; can set up a tunnel without checking digital certificates and also support tokens

93 Enterprise Security Model

94 Wireless Security Update Mark Ciampa Western Kentucky University