Post on 22-Dec-2015
transcript
Introduction to Wireless Introduction to Wireless SecuritySecurity
Lecture 10Lecture 10
Information and Nework Security 2
OutlineOutline
The importance of Wireless communications The importance of Wireless communications Wireless networks and security risksWireless networks and security risks
Why is it so hard to secure wireless communications?Why is it so hard to secure wireless communications? Wireless communications and network security issuesWireless communications and network security issues
WEPWEP WAPWAP Bluetooth (reading)Bluetooth (reading) WWAN and security (reading)WWAN and security (reading)
Principles for securing a wireless networkPrinciples for securing a wireless network What need to be done to secure a wireless network?What need to be done to secure a wireless network?
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ReferencesReferences
http://www.practicallynetworked.com/thttp://www.practicallynetworked.com/tools/wireless_articles_security.htmools/wireless_articles_security.htm
http://www.cs.rice.edu/~astubble/wep/http://www.cs.rice.edu/~astubble/wep/wep_attack.pdfwep_attack.pdf
http://www.drizzle.com/~aboba/IEEE/http://www.drizzle.com/~aboba/IEEE/ http://www.hpl.hp.com/personal/Jean_http://www.hpl.hp.com/personal/Jean_
Tourrilhes/Linux/Tourrilhes/Linux/ http://www.cis.ohio-state.edu/~jain/refhttp://www.cis.ohio-state.edu/~jain/ref
s/wir_refs.htms/wir_refs.htm
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Huge growth of wireless Huge growth of wireless communication devices, wireless communication devices, wireless laptops, PDA, handheld PC, Mobile laptops, PDA, handheld PC, Mobile phone, etc.phone, etc.
Pictures borrowed from other authors
Importance of wireless communicationsImportance of wireless communicationsGrowing of Wireless DevicesGrowing of Wireless Devices
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Wireless Networks and Mobile Wireless Networks and Mobile Commerce servicesCommerce services
Wireless servicesm-commerce
Entertainment•Music•Games•Graphics•Video•etc
Communication•e-mail•Chatrooms•Video-conferencing•etc
Transactions•Banking•Broking•Shopping•Auctions•Betting•Booking & reservations•etc
Information•News•City guides•Directory services•Maps•Traffic & weather•Corporate information•etc
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Wireless Communication UsageWireless Communication Usage
InternetInternet revolution has lead to the emergence of e- revolution has lead to the emergence of e-
commerce marketcommerce market
– Around 105 million Yahoo! subscribers in 2001Around 105 million Yahoo! subscribers in 2001
Expansion of Expansion of WirelessWireless devices has lead to the devices has lead to the
explosive growth of mobile communicationsexplosive growth of mobile communications
– More than 200 million wireless subscribers in More than 200 million wireless subscribers in
20012001
– Around 1 billion by 2004 (estimated)Around 1 billion by 2004 (estimated)
WirelessWireless & & Internet Internet convergence has lead to the convergence has lead to the
explosion of the Mobile Commerce marketexplosion of the Mobile Commerce market
– Very HighVery High number in the future! number in the future!
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Wireless connectionsWireless connectionsEnd-to-End Simple Wireless LANEnd-to-End Simple Wireless LAN
WNICWNIC
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Simple Wireless LAN (e.g)Simple Wireless LAN (e.g)
users
Access Point
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WLAN Protocol SetupWLAN Protocol Setup
Access Point
Mobile Station
Mobile Station
Mobile Station
SharedKey
LAN
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A Possible Wireless Network (e.g)A Possible Wireless Network (e.g)
Internet
users
e-businesses
Internet
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Example of a WLANsExample of a WLANs
Try to find out if there is a WLAN on Try to find out if there is a WLAN on Caulfield campusCaulfield campus
Try to find out who else has a WLAN in Try to find out who else has a WLAN in Melbourne (in the city area)Melbourne (in the city area)
Check other university campuses, Check other university campuses, hotels with conference rooms, hotels with conference rooms, libraries, etc.libraries, etc.
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Wireless Computing and Security Wireless Computing and Security
Wireless computing offers many benefits:Wireless computing offers many benefits:PortabilityPortabilityFlexibilityFlexibility Increased productivityIncreased productivityLower cost installationsLower cost installations
Wireless computing provides new working Wireless computing provides new working environments and imposes new security environments and imposes new security issues.issues.Protecting the networks against attacks, Protecting the networks against attacks,
ensuring secure data transmission, detecting ensuring secure data transmission, detecting and tracking down any penetration to a wireless and tracking down any penetration to a wireless network are difficult.network are difficult.
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Wireless Communications and RisksWireless Communications and Risks
RisksRisksWireless technology has not advanced fast Wireless technology has not advanced fast
enough to allow better security mechanisms to enough to allow better security mechanisms to be implemented.be implemented.
Currently wireless traffic is not secureCurrently wireless traffic is not secure E.g: sensitive data may be transmitted over unsecured E.g: sensitive data may be transmitted over unsecured
connectionsconnections Credit Card numbersCredit Card numbers Corporate emailCorporate email Usernames/passwordsUsernames/passwords
Expert hackers can access wireless networks Expert hackers can access wireless networks easier than wired oneseasier than wired ones
Security holes in wireless systems can be Security holes in wireless systems can be quickly found with the ideas and tools that have quickly found with the ideas and tools that have been used with wired networksbeen used with wired networks
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Wireless Network Security IssuesWireless Network Security Issues
Wireless devices are “radios” and Wireless devices are “radios” and have limitations in capacityhave limitations in capacityWireless communication medium is the Wireless communication medium is the
airwave and openly exposed to intrudersairwave and openly exposed to intrudersA wireless port of a wireless Local Area A wireless port of a wireless Local Area
Network (WLAN) is logically equivalent to Network (WLAN) is logically equivalent to an Ethernet port without any protectionan Ethernet port without any protection
Possible loss of confidentiality and Possible loss of confidentiality and integrity and the thread of denial of integrity and the thread of denial of serviceservice
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Wireless LAN Security Issues (e.g)Wireless LAN Security Issues (e.g)
Cracking the encryption keyCracking the encryption key Reading and decrypting wireless LAN packets are not as hard as Reading and decrypting wireless LAN packets are not as hard as
in the case of wired networks due to the key generation problemsin the case of wired networks due to the key generation problems Unauthorised accessingUnauthorised accessing
An unregistered user can easily access to a wireless LAN An unregistered user can easily access to a wireless LAN resource if an Access Point is not correctly configured.resource if an Access Point is not correctly configured.
The user can also access to the main wired network via the The user can also access to the main wired network via the wireless LAN wireless LAN
Authorised users abusing the systems, eg:Authorised users abusing the systems, eg: Unauthorised sniffing of other traffic by usersUnauthorised sniffing of other traffic by users Eavesdropping on other users trafficEavesdropping on other users traffic
Setting up phantom Access Points to gather data from Setting up phantom Access Points to gather data from genuine usersgenuine users
Setting up an unknown wireless LAN inside a corporation => Setting up an unknown wireless LAN inside a corporation => making wired network more vulnerablemaking wired network more vulnerable
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Wireless LAN Security - BackgroundWireless LAN Security - Background
Most Wireless Network Interface Card (WNIC) Most Wireless Network Interface Card (WNIC) and Access Point (AP) are used for WLANand Access Point (AP) are used for WLAN
Each WNIC or AP must be manually Each WNIC or AP must be manually configured with some shared keyconfigured with some shared key
The sending and receiving stations/AP share The sending and receiving stations/AP share a secret keya secret key
A sending station encrypts each frame before A sending station encrypts each frame before transmissiontransmission
Receiving station decrypts the frameReceiving station decrypts the frame
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Wireless LAN Security - Wireless LAN Security - 802.x,802.x,802.11b (commercial name as WiFi),etc.802.11b (commercial name as WiFi),etc.
The 802.xThe 802.xFamily of standards set forth by IEEE to define Family of standards set forth by IEEE to define
the specifications for wireless LANs:the specifications for wireless LANs:
Wireless Medium Access Control (WMAC):Wireless Medium Access Control (WMAC): regulate access to the mediumregulate access to the medium Use 48 bits as Ethernet addresses on wired LANs Use 48 bits as Ethernet addresses on wired LANs
Physical Layer SpecificationsPhysical Layer Specifications Spectrum, distance, bit rate, etcSpectrum, distance, bit rate, etc
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IEEE 802.X standardsIEEE 802.X standards
Borrowed from RFC
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Security problems with WLANsSecurity problems with WLANs
Easy access: signals fly into the airEasy access: signals fly into the air Rouge Access PointRouge Access Point
Set up by experts or normal usersSet up by experts or normal users Unauthorised access to servicesUnauthorised access to services
Majority of access points are put in services with minimum Majority of access points are put in services with minimum modifications to their default configurationmodifications to their default configuration
Denial of servicesDenial of services Attackers can inject traffic into a wireless network without being Attackers can inject traffic into a wireless network without being
attached to an AP; A ping flood can be launched from a wired attached to an AP; A ping flood can be launched from a wired network to overwhelm the limited-capacity wireless devices network to overwhelm the limited-capacity wireless devices
WMAC spoofing and session hijackingWMAC spoofing and session hijacking Attackers can observe MAC addresses of stations and adopt Attackers can observe MAC addresses of stations and adopt
those addresses for malicious transmissionsthose addresses for malicious transmissions Traffic analysis and eavesdroppingTraffic analysis and eavesdropping
Frame headers can be transmitted in the clear form and are Frame headers can be transmitted in the clear form and are visible to anybody with a wireless network analyservisible to anybody with a wireless network analyser
Chain attacks to wired networks via a wireless oneChain attacks to wired networks via a wireless one
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Wireless LAN Security - WEPWireless LAN Security - WEP
Wired Equivalent Privacy (WEP) Wired Equivalent Privacy (WEP) Designed by the IEEE aimed to prevent Designed by the IEEE aimed to prevent
eavesdroppers and unauthorised eavesdroppers and unauthorised connections to a wireless networkconnections to a wireless network
WEP tries to achieve similar security as a WEP tries to achieve similar security as a wired LANwired LAN Confidentiality: protect the contents of wireless traficConfidentiality: protect the contents of wireless trafic Access Control: prevent an adversary from using your Access Control: prevent an adversary from using your
wireless networkwireless network Data Integrity: prevent the modification of data in transitData Integrity: prevent the modification of data in transit
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Security with WEPSecurity with WEP
RC4(iv,k)
iviv – the initialization vector, a random sequence of bits – the initialization vector, a random sequence of bits kk – the secret key – the secret key
RC4RC4 – – a stream cipher, believed to be securea stream cipher, believed to be secure Takes in an Takes in an initialization vector initialization vector and and keykey; produces a ; produces a key streamkey stream
ciphertexciphertex
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Security with WEPSecurity with WEP
A secret key (k) shared between the communicating parties is distributed and each packet is encrypted with shared secret key + initialization vector (IV) [24 bits]
The sender: Computes a checksum c(M) Picks an IV v, and generate a keystream RC4(v,k) XORs <M,c(M)> with the keystream to get the ciphertext Transmits v and the ciphertext over the radio link Upon receipt, the receiver: Uses the transmitted v and the shared k to generate the
keystream RC4(v,k) XORs the ciphertext with RC4(v,k) to get <M',c'> Checks to see if c' = c(M') If it is, accepts M' as the message transmitted
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WEP and Security IssuesWEP and Security Issues
The The keystreamkeystream for WEP is RC4(v,k), which depends for WEP is RC4(v,k), which depends only on v and k. k is a fixed shared secret, that is only on v and k. k is a fixed shared secret, that is rarely changedrarely changed
In many setups, many users share the same k In many setups, many users share the same k So the So the keystreamkeystream depends only on v depends only on v If two packets ever get transmitted with the same If two packets ever get transmitted with the same
value of v, you reuse the value of v, you reuse the keystreamkeystream, which is , which is vulnerable vulnerable
Since v gets transmitted in the clear form for each Since v gets transmitted in the clear form for each packet, an attacker can easily tell when a value of v packet, an attacker can easily tell when a value of v is reused is reused
How many possible values of v are there? v only How many possible values of v are there? v only occupies 24 bits of the header, so at most there are occupies 24 bits of the header, so at most there are 2^24 2^24
After 2^24 packets, there will be a repeat one!After 2^24 packets, there will be a repeat one!
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Wireless LAN Security with WEPWireless LAN Security with WEP
Since IV is relatively short & shared keys Since IV is relatively short & shared keys that remain static, eventually WEP may use that remain static, eventually WEP may use the same IV for different data packets for a the same IV for different data packets for a large busy network in a short period of timelarge busy network in a short period of time
If you can collect enough packets based on If you can collect enough packets based on the same IV, you can work out the secret the same IV, you can work out the secret keykey
802.11 with WEP does not provide any 802.11 with WEP does not provide any functions that support the exchange of keys functions that support the exchange of keys among stations => system administrators or among stations => system administrators or users generally use the same keys for a users generally use the same keys for a long timelong time
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WEP and its VulnerabilitiesWEP and its Vulnerabilities
WLAN tools that recover encryption keysWLAN tools that recover encryption keysExploits weakness in Key Scheduling Algorithm Exploits weakness in Key Scheduling Algorithm
of RC4of RC4Requires 5-10 million encrypted packetsRequires 5-10 million encrypted packetsOnce enough packets have been gathered, can Once enough packets have been gathered, can
guess the encryption key in under a secondguess the encryption key in under a secondFor more information:For more information:
http://airsnort.sourceforge.net/http://airsnort.sourceforge.net/ http://wepcrack.sourceforge.net/http://wepcrack.sourceforge.net/
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Wireless attacks (e.g)Wireless attacks (e.g)
Session hijackingSession hijackingOccurs because of race conditions in 802.x and Occurs because of race conditions in 802.x and
802.x state machines802.x state machinesA hacker waits for successful authenticationA hacker waits for successful authenticationThen, breaks the user’s connection and Then, breaks the user’s connection and
impersonates herimpersonates herThe hacker can exploit the user’s session until The hacker can exploit the user’s session until
timeout timeout Man-in-the-MiddleMan-in-the-Middle
Since 802.x uses only one-way authentication a Since 802.x uses only one-way authentication a hacker can act as an AP to usershacker can act as an AP to users
APs are trusted entities => bad design=> APs are trusted entities => bad design=> security problems for WLANssecurity problems for WLANs
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WEP and Security ConcernsWEP and Security Concerns
802.x with WEP is not enough802.x with WEP is not enough Should put more things together for Should put more things together for
securitysecurity Need another encryption protocol Need another encryption protocol
provide better securityprovide better security ProblemsProblems
Need hardware accelerationNeed hardware accelerationOptimize for speed and efficiencyOptimize for speed and efficiencyTradeoff in security schemeTradeoff in security scheme
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Wireless LAN Security – Enhanced WEPWireless LAN Security – Enhanced WEP
Digital Certificates can be used for Digital Certificates can be used for distributing keys dynamically to WLANdistributing keys dynamically to WLANSolves key re-use problemSolves key re-use problem
Enhance authentication between Enhance authentication between clients and APs via an authentication clients and APs via an authentication serverserver
Increase key length and change keys Increase key length and change keys after a certain number of framesafter a certain number of frames
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Wireless Application Protocol (WAP)Wireless Application Protocol (WAP)
WAP tries to providesWAP tries to provides AuthenticationAuthentication ConfidentialityConfidentiality IntegrityIntegrity
WAP security gatewayWAP security gateway Server product dedicated to providing WTLS sessions Server product dedicated to providing WTLS sessions Works with today’s WAP phonesWorks with today’s WAP phones
WebServerWeb
Server
users
WAP Gateway
WTP/WTLSInternet
HTTP/SSL
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Wireless Application Protocol (WAP)Wireless Application Protocol (WAP)
Designed to provide Internet Designed to provide Internet connections for wireless users, connections for wireless users, particularly mobile phone usersparticularly mobile phone users
Employs WML, WTLSEmploys WML, WTLS Uses WAP Identity Module to provide Uses WAP Identity Module to provide
resistance to device-tamperingresistance to device-tampering
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Wireless Application Protocol (WAP)Wireless Application Protocol (WAP)
A WAP-enable mobile phone can execute an application that A WAP-enable mobile phone can execute an application that requests a URL or runs a script on a standard web serverrequests a URL or runs a script on a standard web server
The agent on the phone sends an URL requests to a WAP The agent on the phone sends an URL requests to a WAP gateway in the form specified by WTP (wireless Transaction gateway in the form specified by WTP (wireless Transaction Protocol)Protocol)
WAP gateway translates the request into HTTP request WAP gateway translates the request into HTTP request (if the (if the transmission is sent using WTLS, the gateway also translates the data into HTTPS)transmission is sent using WTLS, the gateway also translates the data into HTTPS)
The gateway forwards (or encrypts then forwards) the The gateway forwards (or encrypts then forwards) the (HTTP/HTTPS) request to the web server(HTTP/HTTPS) request to the web server
Web server processes the request and returns the results to Web server processes the request and returns the results to the gateway (using HTTP/SSL) the gateway (using HTTP/SSL)
The gateway receives the results and does necessary The gateway receives the results and does necessary translations (if it is not done by a WAP server) and translations (if it is not done by a WAP server) and decryptionsdecryptions
The gateway then sends the results to the phoneThe gateway then sends the results to the phone
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WAP SecurityWAP Security
The security of WAP systems is left to The security of WAP systems is left to architects and developersarchitects and developers
WTLS does not provide end-to-end securityWTLS does not provide end-to-end security WAP has common limitations as other WAP has common limitations as other
wireless technologies such as size, space, wireless technologies such as size, space, and speed.and speed.
WAP gateways are trusted to encrypt and WAP gateways are trusted to encrypt and decrypt datadecrypt data
WML and WML script are limited subsets of WML and WML script are limited subsets of languages with known security controllanguages with known security control
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How about Using PKI to Enhance Security of How about Using PKI to Enhance Security of Wireless Environments?Wireless Environments?
users
e-businesses
Public Key Infrastructure can be used to enhance wireless security
Borrowed from Paul Ho
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Problems with Using PKI to Enhance Problems with Using PKI to Enhance Security of Wireless Environments.Security of Wireless Environments.
Wireless devices may not have Wireless devices may not have sufficient power capacity to use PKI sufficient power capacity to use PKI for securityfor security
Applications may require fast Applications may require fast processingprocessing
Security protocols can employ private Security protocols can employ private key distribution to resolve the low-key distribution to resolve the low-computational power problemcomputational power problem
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Secure a Wireless NetworkSecure a Wireless Network
Maintain a secure wireless network requires Maintain a secure wireless network requires significant effort and resources and we need to:significant effort and resources and we need to:
Develop an organisational security policy that addresses the use of all handheld devices
Ensure users on the network are fully trained in computer security awareness and the risks associated with handheld devices
Conduct ongoing, random security audits to monitor and track mobile devices
Ensure external boundary protection is in place around the perimeter of the building or buildings of the organisation
Deploy physical access controls to the building and other secure areas (e.g., photo ID, card badge readers, etc)
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Secure a Wireless NetworkSecure a Wireless Network
Label all handheld devices with the owner and organization's information
Ensure that users know where to report a lost or stolen device
Ensure that devices are stored securely when left unattended
Make sure that add-on modules are adequately protected when not in use
Enable a “power-on” password for each handheld device
Ensure proper password management (aging, complexity criteria, etc.) for all handheld devices
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Secure a Wireless NetworkSecure a Wireless Network
Synchronise devices with its corresponding PC regularly Delete sensitive data from the handheld device and archive it
on the PC when no longer needed on the handheld Turn off Infrared ports during periods of inactivity Install antivirus software on all handheld devices Install personal firewall software on all handheld devices Ensure that PDAs are provided with secure authorization
software/firmware Make sure that a user can be securely authenticated when
operating locally and remotely Use enterprise security applications to manage handheld
device security Ensure security assessment tools are used on handheld
devices
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Key Security RequirementsKey Security Requirements
To be able to deal with wireless security problems, To be able to deal with wireless security problems, there are needs for:there are needs for:
Security from a wireless station or AP to Security from a wireless station or AP to A wireless networkA wireless networkA wired networkA wired network InternetInternet
From one wireless network to another From one wireless network to another A global standards-based open architecture for all A global standards-based open architecture for all
mobile devices is criticalmobile devices is critical Device and bandwidth independence regulations Device and bandwidth independence regulations
need to be enforcedneed to be enforced