Vulnerabilidades Wi-Fi de dispositivos móviles en redes empresariales 802.1x/EAP

Transcripción

1 w w w. d i n o s e c. c o d i n o s e c Vulnerabilidades Wi-Fi de dispositivos móviles en redes empresariales 802.1x/EAP Raúl Siles 18 marzo 2014 Try IT! UPM 2014 Dino Security S.L.

2 w w w. d i n o s e c. c o d i n o s e c Mobile Devices Wi-Fi Vulnerabilities in 802.1x/EAP Enterprise Networks Raúl Siles March 18, 2014 Try IT! UPM 2014 Dino Security S.L.

3 Outline Wi-Fi challenges nowadays Wi-Fi (mobile) clients behavior The PNL Wi-Fi network impersonation Attacking Wi-Fi enterprise clients Wi-Fi clients security recommendations References 3

4 Wi-Fi Challenges Nowadays? 4

5 Wi-Fi Challenges Nowadays? 5

6 Wi-Fi Security Challenges Nowadays? Super Bowl Security Command Center 2014: Broadcast on TV 6

7 Wi-Fi Security Challenges Nowadays? Target: Wi-Fi Infrastructure vs. Wi-Fi Clients 7

8 Wi-Fi (Mobile) Clients Behavior 8

9 How Wi-Fi Clients Work? Users connect to Wi-Fi networks by 1. Selecting them from the list of currently available networks in the area of coverage 2. Adding them manually to the Wi-Fi client Security settings are mandatory (if any) Open, WEP, WPA(2)-Personal & WPA(2)- Enterprise Networks are remembered and stored for future connections: list of known networks The Preferred Network List (PNL) 9

10 The Preferred Network List (PNL) 10

11 Disclosing the PNL How Wi-Fi clients discover available Wi-Fi networks? Do Wi-Fi clients really disclose their PNL? By default Hardware, firmware, Wi-Fi drivers & supplicant (SW) Hidden Wi-Fi networks Do mobile devices really disclose their PNL? Manually adding Wi-Fi networks Is Android constantly scanning for Wi-Fi networks? ios 5.x case study Weird and difficult to reproduce scenarios 11

12 How Wi-Fi Clients Discover Available Wi-Fi Networks? Passive scan Beacons Every 100ms (10 frames/sec) SSID? Active scan Probe request / response (Wildcard or broadcast) SSID? 12

13 Hidden Wi-Fi Networks Hidden Wi-Fi networks (cloaked or non-broadcast) Still today a very common security best practice with relevant security implications for the Wi-Fi clients Beacon frames do not contain the SSID (empty) Visible (or broadcast) Wi-Fi networks include the SSID in their beacon frames Wi-Fi clients need to know the SSID to connect to the network So how Wi-Fi clients connect to hidden Wi-Fi networks? Wi-Fi clients have various networks (SSIDs) in their PNL Wi-Fi clients have to specifically ask for the hidden Wi-Fi networks in their PNL by sending probe requests containing the SSID As a result they have to disclose their PNL!! PNL was disclosed by Wi-Fi clients in the past (2005; Win XP fix in 2007) 13

14 Security Risks of Disclosing the PNL 14

15 Security Risks of Disclosing the PNL An attacker can impersonate the various Wi-Fi networks available in the PNL Different methods based on the security settings People didn t pay enough attention to this because there was no name for it! War Standing or War Statuing (Statue) 15

16 War Standing Risks 16

17 Wi-Fi Network Impersonation 17

18 Wi-Fi Network Impersonation (1/2) When entries in the PNL are disclosed by Wi-Fi clients someone can force the victims to (silently) connect to the attacker s Wi-Fi network Karma-like attacks (since 2004) AP impersonation (or fake AP): anywhere in the world Evil-twin: area of coverage of the legitimate network Strongest signal wins (or less battery drawing network) The victim shares the network with the attacker Full network connectivity at layer 1&2 and above MitM: Man-in-the-Middle attacks 18

19 Wi-Fi Network Impersonation (2/2) Fully impersonate the Wi-Fi network AP, DHCP server, DNS server, routing and NAT capabilities, RADIUS server Two prerequisites SSID (Wi-Fi network name) Disclosed from the PNL Wi-Fi network security type Security type requirements Open, WEP & WPA(2)-Personal, WPA(2)-Enterprise 19

20 Open Wi-Fi Networks 20

21 Attacking Wi-Fi Clients: Open Nobody never ever connects to an open Wi-Fi network! Right? 21

22 WPA(2)-Enterprise Wi-Fi Networks 22

23 Wi-Fi Enterprise Networks Wi-Fi client, access point (AP), and RADIUS server Multiple user credentials allowed (802.1X/EAP types) How to verify the RADIUS certificate? CN, CA, expiration + revocation & purpose There is no URL like in the web browsers (X.509 CN) server 23

24 FreeRADIUS-WPE FreeRADIUS-Wireless Pwnage Edition (WPE) SchmooCon 2008: Joshua Wright & Brad Antoniewicz Attacker impersonates the full Wi-Fi network infrastructure (AP + RADIUS server + ) PEAP & TTLS Inner authentication: MS-CHAPv2 (or others) Username + Challenge/Response (hash) Mutual authentication

25 MS-CHAPv2 Cracking asleap (+v2.1) - Joshua Wright Crack challenge (-C) and response (-R) Dictionary attack (DES x 3) genkeys Precomputed MD4 hashes (indexed list of passwords) Indexed by the last two bytes of MD4 hash (brute force) Challenge (8-byte) & MD4 hash (16-byte) Response (24-bytes) MS-CHAPv2 cloud cracking Defcon 20 (2012): Moxie Marlinspike & David Hulton Brute force attack (2 56 DES) FPGA box: ~ 12-24h & chapcrack (100% success rate = $200) Strength of user passphrase... not any more! 25

26 FreeRADIUS-WPE in Action 26

27 (FreeRADIUS) EAP Dumb-Down Multiple EAP types available Mobile devices seem to prefer to use PEAP (MS-CHAPv2) by default But in reality they use the preferred EAP method set by the RADIUS server GTC-PAP: Log credentials in cleartext Username and passphrase Additionally it might allow automatic full Wi-Fi network impersonation (MitM) SANS SEC575 Strength of the user passphrase is irrelevant 27

28 EAP Dumb-Down in Action 28

29 Mobile Devices Behavior Against FreeRADIUS-WPE & EAP Dumb-Down FreeRADIUS-WPE ios: UI & configuration profile Android WP 7.x & 8 BlackBerry 7.x EAP Dumb-Down ios: UI & configuration profile Android WP 7.x & 8 BlackBerry 7.x User creddentials (not just the Wi-Fi secret): Other corporate services? Full MitM connectivity "Why ios (Android & others) Fail inexplicably" 29

30 Full Wi-Fi Network Impersonation For Fun & Profit by Example 30

31 Wi-Fi Network Impersonation Exploitation For Fun 31

32 Wi-Fi Network Impersonation Exploitation For Profit - Goto Fail ios update to (Feb 21, 2014) (iphone 3GS & ipod Touch 4th) OS X 10.9 Mavericks (no patch) Lack of proper certificate validation DHE & ECDHE (CVE )

33 Wi-Fi Clients Security Recommendations 33

34 Wi-Fi Clients Configuration Recommendations Turn off the Wi-Fi interface if not in use Do not configure Wi-Fi networks as hidden Do not add Wi-Fi networks manually to mobile devices (= hidden network) Manage & clean-up the PNL periodically Individually and enterprise level (MDM) Wi-Fi policy: What type of networks? Properly add Wi-Fi enterprise networks 34

35 Wi-Fi Enterprise Recommendations (1/2) Wi-Fi supplicants must always Trust only the specific CA used for the Wi-Fi network Not a good idea to use the full list of public trusted CAs A private CA is a better option than a public CA assuming an attacker cannot get a legitimate certificate from it Define the specific (set of) RADIUS server(s) name(s) used (X.509 CN) Do not provide options to disable certificate validation Define and force the specific EAP type used Define the inner authentication method (e.g. MS-CHAPv2) Do not downgrade to other EAP types (EAP dumb-down) 35

36 Wi-Fi Enterprise Recommendations (2/2) WPA2-Enterprise: Full Wi-Fi network validation Do not ask the user! Wi-Fi Enterprise is inherently broken How to add a new RADIUS server? Modify the config of all Wi-Fi clients in the organization User credentials strength Passphrase EAP/TLS: client digital certificates + PKI WIDS (evil-twin) 36

37 References 37

38 References "Why ios (Android & others) Fail inexplicably" Siles-WiFi.pdf DinoSec Security Advisories "Wi-Fi (In)Security - All Your Air Are Belong To..." _RaulSiles_Taddong_v1.0_2pages.pdf DinoSec Lab Publications DinoSec Lab Tools: istupid 38

39 You think that s air you re breathing now? Morpheus to Neo during the scene when he was teaching him in the virtual dojo on board the ship The Nebuchadnezzer

40 Questions 40

41 w w w. d i n o s e c. c o d i n o s e c R a ú l S i l e s r a u d i n o s e c. c o r a u l s i l e s