| Rev | Author | # | Line |
|---|---|---|---|
| 2 | DanielLawson | 1 | WLUG Meeting - 22 August 2005 |
| 1 | CraigBox | 2 | |
| 2 | DanielLawson | 3 | Location: University of Waikato, [LitB] |
| 4 | Time: 7pm | ||
| 5 | |||
| 6 | DanielLawson is giving a talk on the current state of Wireless Security, covering [WEP], [WPA], [802.11i] and more. | ||
| 6 | DanielLawson | 7 | |
| 8 | [WEP] - Wireline Equivalent Protocol. | ||
| 9 | * Introduced in 1997 as part of [IEEE] [802.11] standard | ||
| 10 | * Attempt to make wireless networks "no less secure" than wired ones | ||
| 11 | |||
| 12 | Authentication: | ||
| 13 | * one-way open authentication ([SSID]) | ||
| 14 | * shared-key authentication | ||
| 15 | |||
| 16 | Encryption: | ||
| 17 | * Wireline Equivalent Privacy ([WEP]) key | ||
| 18 | |||
| 19 | [WEP] keys | ||
| 20 | * 40 (or 104/128 bit) string | ||
| 21 | * uses [RC4] | ||
| 22 | * combined with 24bit Initialization Vector ([IV]) | ||
| 23 | |||
| 24 | Pros: | ||
| 25 | * allows some control over access to network | ||
| 26 | * allows some protection against sniffing. | ||
| 27 | |||
| 28 | Cons: | ||
| 29 | * comprised key = complete breach in security | ||
| 30 | * pain to administer large number of machines | ||
| 31 | * algorithm broken; can break encryption if enough data observed | ||
| 32 | |||
| 33 | [WPA] - Wi-Fi Protected Access | ||
| 34 | * Wi-Fi Alliance assembled a part of the upcoming [802.11i] standardin 2003 | ||
| 35 | * [TKIP] for encryption | ||
| 36 | * per-user, not per-device authentication and key distribution framework ([802.1X]) | ||
| 37 | * Extensible Authentication Protocol ([EAP]) | ||
| 38 | * Can still use Pre-Shared Keys ([PSK]) | ||
| 39 | |||
| 40 | [TKIP] | ||
| 41 | * [RC4] based | ||
| 42 | * Per-packet keying, [IV] changes, broadcast key rotation to get around [WEP] insecurities | ||
| 43 | * Message Integrity Check ([MIC]) to prevent [MITM] attacks | ||
| 44 | |||
| 45 | [802.1X] | ||
| 46 | * [IEEE] standard for port-based authentication | ||
| 47 | * Strong mutual authentication between client and auth server | ||
| 48 | * Authenticates a client through user-supplied credentials, rather than a computer | ||
| 49 | |||
| 50 | Keys | ||
| 51 | * [TKIP] keys dynamically generated and distributed | ||
| 52 | * Master key generated to seed key hierarchy | ||
| 53 | * Master key given to [AP] and client | ||
| 54 | * Per-user, per-session encryption - brute forcing attack very difficult! | ||
| 55 | |||
| 56 | [EAP] | ||
| 57 | * Extensible Authentication Protocol | ||
| 58 | * Allows different auth methods without infrastructure changes | ||
| 59 | * Originally designed for [PPP] connections, adapted for [LAN] ([EAPOL|EAP]) | ||
| 10 | CraigBox | 60 | * Many [EAPOL|EAP] auth protocols exist - [MD5], [TLS], [CHAP], [MS-CHAPv2], [SIM] (Subscriber Identity Module), EAP-AKA (Authentication and Key Agreement), GTC (Generic Token Card) |
| 61 | * Some methods add a tunnel for authentication information - [PEAP|EAP], [EAP-TTLS|EAP] (Tunneled [TLS]) | ||
| 6 | DanielLawson | 62 | |
| 63 | [WPA2] | ||
| 64 | * Full [IEEE] [802.11i] standard | ||
| 65 | * Ratified in July 2004 | ||
| 66 | * [TKIP], [802.1X]/[EAP] | ||
| 67 | * Added [AES] encryption | ||
| 68 | |||
| 69 | [AES] | ||
| 8 | PerryLorier | 70 | * Counter cipher-block chaining mode ([CBC]), as opposed to [WEP]'s single stream cipher |
| 6 | DanielLawson | 71 | * Variable keys sizes - 128, 192, 256 bits |
| 72 | * "Good security" | ||
| 73 | |||
| 74 | |||
| 75 | Practical Wireless Security | ||
| 76 | |||
| 77 | Encryption Methods: | ||
| 78 | |||
| 79 | * Only very early [802.11b] devices lack [WEP] support, .: [WEP] is a good "minimum" | ||
| 80 | * [WEP] adds some overhead - might see some drop in throughput. Better than handing out your email password? | ||
| 81 | * BUT, [WEP] can be broken. | ||
| 82 | |||
| 83 | * Some [802.11b] and most [802.11g] (all?) devices have [WPA] support | ||
| 84 | * [WPA] addresses most of the problems | ||
| 85 | * Can still use [PSK] | ||
| 86 | * [PSK] used to seed the [TKIP] key hieararchy | ||
| 87 | * Changing keys, so bruteforce attack not as feasable | ||
| 88 | * [WPA] shown to still be insecure if keys are less than 20 characters long | ||
| 89 | |||
| 90 | * [WPA2] has good encryption ([AES]) | ||
| 91 | * Some [WPA] implementations have [AES] support as well. This is also good! | ||
| 92 | |||
| 93 | Is [PSK] ok? | ||
| 94 | |||
| 95 | * For small networks, [PSK] works well | ||
| 96 | * Know the userbase | ||
| 97 | * Can control when people add / leave network, and change keys appropriately | ||
| 98 | * Low admin time | ||
| 99 | * Perfect for home / small office use | ||
| 100 | |||
| 101 | When is [PSK] not ok? | ||
| 102 | * Large networks ( > 20 machines ?) | ||
| 103 | * Large admin cost | ||
| 104 | * Dynamic user base (eg cafe net, conference) | ||
| 105 | * If per-user security is needed (eg cafe net, conference) | ||
| 106 | |||
| 107 | |||
| 108 | Other considerations for wireless security: | ||
| 109 | |||
| 110 | End-to-end security | ||
| 111 | * [WEP], [WPA], [WPA2] only secure "in the air" transmissions. No security on remaining wired transmissions (which might go over an unsecured wireless backhaul!) | ||
| 112 | * Use [VPN]s | ||
| 113 | |||
| 114 | Multiple [SSID]s | ||
| 115 | * Can be used to provide different levels of security | ||
| 116 | * different user groups | ||
| 117 | |||
| 118 | [VLAN]s | ||
| 119 | * Many [AP]s now support VLAN tagging | ||
| 120 | * Per-port (per [AP]) | ||
| 121 | * [MAC] address (per physical computer - bad) | ||
| 122 | * Per [SSID] ([SSID]s are sniffable) | ||
| 123 | * Per user (via [802.1X]) | ||
| 124 | |||
| 125 | Rogue [AP] detection | ||
| 126 | * Network only secure as long as you control all aspects of it | ||
| 127 | * insecure [AP]s without strict security controls can cause major security breaches | ||
| 128 | |||
| 129 | |||
| 130 | Implementation of WPA-RADIUS with 802.1X via FreeRadius | ||
| 10 | CraigBox | 131 | |
| 132 | See also: | ||
| 133 | |||
| 134 | * [How to set up a wireless network using Windows server WPA and RADIUS|http://www.hansenonline.net/Networking/wlanradius.html] | ||
| 13 | DanielLawson | 135 | * [Comparison of TTLS and PEAP|http://www.oreillynet.com/pub/a/wireless/2002/10/17/peap.html] |
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