Wireless Engineering Body of Knowledge (WEBOK)Wireless Security

WEBOK Tutorial

Paul Kubik

What is Wireless Security?

Confidentiality: the communication data are only disclosed to authorized users.

Integrity: the data in the communication retain their veracity and are not able to be modified by unauthorized users.

Availability: authorized users are granted timely access and sufficient bandwidth to access the data.

What is Wireless Security?

Why is Wireless Security important? Fraud, Theft – Stealing customer login details from a WiFi hotspot Sabotage – Disabling a local 2G cellular network using a jamming

device Espionage – Stealing a phonebook from a mobile phone via

bluetooth Malicious – Distribution of Mobile viruses, unsolicited Bluetooth

advertising etc.

How can we protect technology through Security? Encryption – protects the information stored in a message Authentication – validates the identity of end-points in a

communication Authorization - restricts access to a service through the use of

authentication systems. Certification – authentication of end-points by a third party

What is Wireless Security? What type of attacks are there?

brute-force attack authenticate by incrementing through every possible combination of a password

dictionary attack authenticate by guessing the password from a library of common words

Man-in-the-middle Attacker actively intercepts the path of communications between two legitimate parties, thereby obtaining authentication credentials and data. Attacker can then masquerade as a legitimate party.

Spoofing Attacker impersonates an authorized user and gains certain unauthorized privileges.

Replay attack Attacker passively monitors transmissions and retransmits messages, acting as if the attacker were a legitimate user.

Denial of service Attacker prevents or prohibits the normal use or management of networks or network devices.

What is Wireless Security?

Common concepts in security Private Key - two (or more) parties share the same

key, and that key is used to encrypt data from clear-text to a cipher-text. Private key cryptography relies on keeping the key secret

Eg. AES, DES, 3-DES Public Key – each party has a pair of keys. One key is

public and the other is private. A message encrypted with the public key can be decrypted with the private key. The public key can be made known to all parties (including attackers). The private key is kept secret.

Eg. RSA, Diffie-Hellman

Network Access Control

Network Access Control is used to authenticate, authorize and account for a user or client on the network

Challenge-Response Authentication The authenticating party asks for information that

could only be known to the user Network Access Control protocols:

RADIUS Diameter Extensible Access Protocol

Network Access Control – RADIUS

User authenticates with NAS using a username/password

NAS sends Access-request to RADIUS server

RADIUS server generates an Access-Challenge for the user.

User calculates hash and sends response to the RADIUS server

User is authenticated as an end-point in the network (Access-Accept)

Network Access Control – Diameter

Failover: supports application-layer acknowledgment and defines failover algorithms.

Confidentiality: IPSEC support is mandatory for Diameter and TLS is optional.

Reliable transport: Transmission Control Protocol (TCP) or STCP protocols.

Server-initiated messages: Mandatory support allowing re-authentication/re-authorization

Auditability: Data-object security mechanisms preventing against untrusted proxies modifying attributes or packet headers

Capability negotiation: Error messages, capability negotiation, mandatory/non-mandatory flags for attributes (AVPs).

Peer discovery and configuration: Dynamic discovery of peers using Domain Name System (DNS). Dynamic session keys via transmission-level security.

Roaming support: Supports user roaming, interdomain exchange of user and accounting information.

Network Access Control - EAP

Extensible Access Protocol is a authentication framework, not a specific implementation. It defines methods and common functions used for authentication.

Supplicant – The party that wants to be authenticated Authenticator - The party that demands proof of authentication Four types of messages are defined in EAP: request, response,

success, and failure. The authenticator sends a request message to the

supplicant asking for a response message to authenticate. If the authentication is successful, a success message is sent to the supplicant; if not, a failure message is sent.

Encapsulation on IEEE wireless LANs, IEEE-802.11i WPA, WPA2 Standard EAP-TLS, EAP-TTLS, PEAP

Network Access Control – 802.1x

An authentication protocol based on EAP

The supplicant is the authenticating user, sends an EAP-Start message to the authenticator

The authenticator is the Wireless Access Point (802.11), sends an EAP-Request Identity to the supplicant

The authenticator only allows the supplicant to generate EAP traffic (EAPoL) until it has been authenticated

The authentication server determines whether a supplicant is authenticated (eg RADIUS server)

NAC Example (1) The Traffic Capture is RADIUS

conversation using EAP-TLS Supplicant

MAC: Z-Com_64:61:dc Authenticator

MAC: 3com_7a:eb:fcIP Addr: 192.168.4.62

Auth ServerIP Addr: 192.168.4.51

3: The supplicant sends an EAP Response containing “mobile@lab”

4: The authenticator sends a RADIUS packet to the authentication server containing the connection details

https://www.openpacket.org/

NAC Example (2) 8: The authentication server

sends an access-challenge to verify the supplicant’s identity.

10: The authenticator requests that the supplicant use EAP-TLS to verify the user identity

26: The authentication server decides that client certificate is valid and the supplicant is a known user

29: Now the authenticator must still make sure that the supplicant has the correct WPA pre-shared key

Wireless LAN Security

Service Set Identifier (SSID) - wireless LAN name used client to identify the network

Media Access Control (MAC) address - administrator may specify which MACs are allowed to access the network

Security Algorithm – used for network authentication, including WEP, WPA or WPA2

WLAN Security - WEP

WEP Initialization Vector (IV) – 24-bit seed value to

initialize the cryptographic system Stream cipher (RC4) – 40-bit, 104-bit keys.

Generates a key which is XOR’ed with the message. A different sequence is used for each message

Integrity checking (CRC-32) – computed and encrypted on each message, becomes the Integrity Check Value (ICV) on the frame

WLAN Security - TKIP

TKIP is used to enhance the RC4 cipher. It is designed to strengthen the WEP protocol (based on RC4) without significant performance degradation

Message encryption using the RC4 algorithm Integrity protection, using the Message Integrity

Code (MIC) Replay prevention, using a frame sequencing

technique; and Use of a new encryption key for each frame.

WLAN Security - CCMP

CCMP is used to enhance the AES cipher. AES is the secure cipher used by WPA/WPA2

CCMP provides authentication and privacy features based on AES Integrity control (MIC) Message encryption (payload only)

CCMP is designed for a 128-bit key and block size

WLAN Security – WPA/WPA2

WPA RC4 Cipher. TKIP/MIC Encryption Implements partial 802.11i standard TKIP generates a sequence of WEP keys based on a master

key. Message Integrity Code (MIC) and ICV (Integrity Check

Value) identify if the packet is tampered with

WPA2 AES Cipher (instead of RC4). AES-CCMP Encryption Implements full 802.11i standard, known as RSN AES is a secure cipher that can be implemented in

hardware. CCMP arranges for Message Integrity Control (MIC) and

Message encryption (payload only)

WLAN Security Example

Securing your network

Enable WPA/WPA2 security on the access point.

Change the default admin password

Change the default SSID and disable broadcast.

Disable DHCP, enable MAC address filtering

Cellular Security

AMPS Security Analog FM system. Unencrypted channels ESN / MIN used for Customer and Handset registration on the network

CDMA Security Subscriber Authentication (CAVE) Subscriber Identity confidentiality (TMSI). No SIM card Spreading sequences on physical channel

GSM Security Subscriber Authentication (A3/COMP128) Subscriber Identity confidentiality (TMSI). Removable SIM card Encryption of Air interface only

UMTS security Mutual authentication (Subscriber and Network) Encryption from Air interface to RNC Mechanism for upgrading security features.

Cellular Security – CDMA

Cellular Security – GSM

IMEI (International Mobile Equipment Identity) is a unique 17 or 15 digit code used to identify a Mobile Station (hardware)

IMSI (International Mobile Subscriber Identity) is a unique 15-digit code used to identify a subscriber (user)

Ki (128-bit) is a secret key shared between the Mobile Station and the HLR

Kc (64-bit) is a Session Key for channel encryption. Kc is generated by the Mobile Station from RAND and Ki using the A8 algorithm.

RAND (128-bit) is a random challenge generated by the HLR. SRES (32-bit) is a Signed Response generated by both the

Mobile Station and the HLR from the RAND to verify identity HLR / AuC – Stores the IMSI and Ki for Mobile Stations EIR – Stores an IMEI black-list to prevent calls from stolen or

unauthorized Mobile Stations.

Cellular Security – GSM

The Mobile Station (MS) signs into the network. The HLR uses the A8 algorithm to generate RAND, SRES and Kc The HLR sends RAND to the RNC and the MS The MS generates SRES from RAND and Ki using the A3 algorithm The MS sends SRES to the MSC The MSC verifies SRES (Mobile) and SRES (HLR) The MS generates Kc from RAND and Ki using the A8 algorithm The BTS verifies Kc (MS) and Kc (HLR) The MS initialises the A5 algorithm with Kc and the frame number An encrypted channel between the MS and the BTS is established

HLRMobileStation

MSCBTS

RAND

SRESKi, Kc Ki, Kc

Bluetooth Security

Bluetooth Security Attacks Bluejacking - attempt to send a phone contact or business card to another

nearby phone for the purpose of spamming information / advertising Bluesnarfing - stealing data (messages, calendar, phone book etc) from the

target device in an unauthorised manner which includes bypassing the usual paring requirement.

Bluebugging - victim device is controlled by the attacker who sends commands to perform actions as if having physical access to the device

Security attributes Bluetooth address : unique device identifier (48-bit). The first 3 bytes are

assigned to a manufacturer. The last 3 bytes allocated by the manufacturer.

"Discoverable" mode : determines whether the device is visible to other devices.

PIN Code : Four digit secret code entered into both devices to establish a Link Key (128-bit)

Frequency hopping : Pseudo-random sequence (1600 hops / second)

Wireless Security

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