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Wireless security

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Wireless security is the prevention of unauthorized access or damage to computers using wireless networks.


Wireless networks are very common, both for organizations and individuals. Many laptop computers have wireless cards pre-installed. The ability to enter a network while mobile has great benefits. However, wireless networking has many security issues.[1] Hackers have found wireless networks relatively easy to break into, and even use wireless technology to crack into wired networks. As a result, it's very important that enterprises define effective wireless security policies that guard against unauthorized access to important resources.[2]

The risks to users of wireless technology have increased as the service has become more popular. There were relatively few dangers when wireless technology was first introduced. Crackers had not yet had time to latch on to the new technology and wireless was not commonly found in the work place. However, there are a great number of security risks associated with the current wireless protocols and encryption methods, and in the carelessness and ignorance that exists at the user and corporate IT level.[3] Cracking methods have become much more sophisticated and innovative with wireless. Cracking has also become much easier and more accessible with easy-to-use Windows or Linux-based tools being made available on the web at no charge.

Some organizations that have no wireless access points installed do not feel that they need to address wireless security concerns. In-Stat MDR and META Group have estimated that 95% of all corporate laptop computers that were planned to be purchased in 2005 were equipped with wireless. Issues can arise in a supposedly non-wireless organization when a wireless laptop is plugged into the corporate network. A cracker could sit out in the parking lot and gather info from it through laptops and/or other devices as handhelds, or even break in through this wireless card-equipped laptop and gain access to the wired network.

Types of unauthorized access

Accidental association

Unauthorized access to company wireless and wired networks can come from a number of different methods and intents. One of these methods is referred to as “accidental association”. When a user turns on a computer and it latches on to a wireless access point from a neighboring company’s overlapping network, the user may not even know that this has occurred. However, it is a security breach in that proprietary company information is exposed and now there could exist a link from one company to the other. This is especially true if the laptop is also hooked to a wired network.

Malicious association

“Malicious associations” are when wireless devices can be actively made by crackers to connect to a company network through their cracking laptop instead of a company access point (AP). These types of laptops are known as “soft APs” and are created when a cracker runs some software that makes his/her wireless network card look like a legitimate access point. Once the cracker has gained access, he/she can steal passwords, launch attacks on the wired network, or plant trojans. Since wireless networks operate at the Layer 2 level, Layer 3 protections such as network authentication and virtual private networks (VPNs) offer no barrier. Wireless 802.1x authentications do help with protection but are still vulnerable to cracking. The idea behind this type of attack may not be to break into a VPN or other security measures. Most likely the cracker is just trying to take over the client at the Layer 2 level.

Ad-hoc networks

Ad-hoc networks can pose a security threat. Ad-hoc networks are defined as peer-to-peer networks between wireless computers that do not have an access point in between them. While these types of networks usually have little protection, encryption methods can be used to provide security.

Non-traditional networks

Non-traditional networks such as personal network Bluetooth devices are not safe from cracking and should be regarded as a security risk. Even barcode readers, handheld PDAs, and wireless printers and copiers should be secured. These non-traditional networks can be easily overlooked by IT personnel who have narrowly focused on laptops and access points.

Identity theft (MAC spoofing)

Identity theft (or MAC spoofing) occurs when a cracker is able to listen in on network traffic and identify the MAC address of a computer with network privileges. Most wireless systems allow some kind of MAC filtering to only allow authorized computers with specific MAC IDs to gain access and utilize the network. However, a number of programs exist that have network “sniffing” capabilities. Combine these programs with other software that allow a computer to pretend it has any MAC address that the cracker desires,[4] and the cracker can easily get around that hurdle.

Man-in-the-middle attacks

A man-in-the-middle attacker entices computers to log into a computer which is set up as a soft AP (Access Point). Once this is done, the hacker connects to a real access point through another wireless card offering a steady flow of traffic through the transparent hacking computer to the real network. The hacker can then sniff the traffic. One type of man-in-the-middle attack relies on security faults in challenge and handshake protocols to execute a “de-authentication attack”. This attack forces AP-connected computers to drop their connections and reconnect with the cracker’s soft AP. Man-in-the-middle attacks are enhanced by software such as LANjack and AirJack, which automate multiple steps of the process. What once required some skill can now be done by script kiddies. Hotspots are particularly vulnerable to any attack since there is little to no security on these networks.

Denial of service

A Denial-of-Service attack (DoS) occurs when an attacker continually bombards a targeted AP (Access Point) or network with bogus requests, premature successful connection messages, failure messages, and/or other commands. These cause legitimate users to not be able to get on the network and may even cause the network to crash. These attacks rely on the abuse of protocols such as the Extensible Authentication Protocol (EAP).

Network injection

In a network injection attack, a cracker can make use of access points that are exposed to non-filtered network traffic, specifically broadcasting network traffic such as “Spanning Tree” (802.1D), OSPF, RIP, and HSRP. The cracker injects bogus networking re-configuration commands that affect routers, switches, and intelligent hubs. A whole network can be brought down in this manner and require rebooting or even reprogramming of all intelligent networking devices.

Caffe Latte attack

The Caffe Latte attack is another way to defeat WEP. It is not necessary for the attacker to be in the area of the network using this exploit. By using a process that targets the Windows wireless stack, it is possible to obtain the WEP key from a remote client.[5] By sending a flood of encrypted ARP requests, the assailant takes advantage of the shared key authentication and the message modification flaws in 802.11 WEP. The attacker uses the ARP responses to obtain the WEP key in less than 6 minutes.[6]

Counteracting risks

Risks from crackers are sure to remain with us for any foreseeable future. The challenge for IT personnel will be to keep one step ahead of crackers. Members of the IT field need to keep learning about the types of attacks and what counter measures are available.

Counteracting security risks

There are many technologies available to counteract wireless network intrusion, but currently no method is absolutely secure. The best strategy may be to combine a number of security measures.

Possible steps towards securing a wireless network include:

  1. All wireless LAN devices need to be secured
  2. All users of the wireless network need to be educated in wireless network security
  3. All wireless networks need to be actively monitored for weaknesses and breaches

MAC ID filtering

Most wireless access points contain some type of MAC ID filtering that allows the administrator to only permit access to computers that have wireless functionalities that contain certain MAC IDs. This can be helpful; however, it must be remembered that MAC IDs over a network can be faked. Cracking utilities such as SMAC are widely available, and some computer hardware also gives the option in the BIOS to select any desired MAC ID for its built in network capability.

Static IP addressing

Disabling at least the IP Address assignment function of the network's DHCP server, with the IP addresses of the various network devices then set by hand, will also make it more difficult for a casual or unsophisticated intruder to log onto the network. This is especially effective if the subnet size is also reduced from a standard default setting to what is absolutely necessary and if permitted but unused IP addresses are blocked by the access point's firewall. In this case, where no unused IP addresses are available, a new user can log on without detection using TCP/IP only if he or she stages a successful Man in the Middle Attack using appropriate software.

802.11 security

Main article: IEEE 802.1X

Regular WEP

Main article: Wired Equivalent Privacy

WEP stands for Wired Equivalent Privacy. This encryption standard was the original encryption standard for wireless. As its name implies, this standard was intended to make wireless networks as secure as wired networks. Unfortunately, this never happened as flaws were quickly discovered and exploited. There are several open source utilities like aircrack-ng, weplab, WEPCrack, or airsnort that can be used by crackers to break in by examining packets and looking for patterns in the encryption. WEP comes in different key sizes. The common key lengths are currently 128- and 256-bit. The longer the better as it will increase the difficulty for crackers. However, this type of encryption is now being considered outdated and seriously flawed. In 2005 a group from the FBI held a demonstration where they used publicly available tools to break a WEP encrypted network in three minutes. WEP protection is better than nothing, though generally not as secure as the more sophisticated WPA-PSK encryption. A big problem is that if a cracker can receive packets on a network, it is only a matter of time until the WEP encryption is cracked.

WEP has some serious issues. First, it does not deal with the issue of key management at all. Either the keys have to be manually given to end users, or they have to be distributed in some other authentication method. Since WEP is a shared key system, the AP uses the same key as all the clients and the clients also share the same key with each other. A hacker would only have to compromise the key from a single user, and he would then know the key for all users.

In addition to key management, a recently published paper describes ways in which WEP can actually be broken (“Weaknesses in the Key Scheduling Algorithm of RC4” by Fluhrer, Mantin and Shamir). This is due to a weakness in RC4 as it is implemented in WEP. If enough traffic can be intercepted, then it can be broken by brute force in a matter of an hour or two. If that weren’t bad enough, the time it takes to crack WEP only grows linearly with key length, so a 104-bit key doesn’t provide any significant protection over a 40-bit key when faced against a determined hacker. There are several freely available programs that allow for the cracking of WEP. WEP is indeed a broken solution, but it should be used as it is better than nothing. In addition, higher layer encryption (SSL, TLS, etc) should be used when possible.

WPAv1

Main article: Wi-Fi Protected Access

Wi-Fi Protected Access (WPA) is a software/firmware improvement over WEP. All regular WLAN-equipment that worked with WEP are able to be simply upgraded and no new equipment needs to be bought. WPA is a trimmed-down version of the 802.11i security standard that was developed by the Wi-Fi Alliance to replace WEP. The TKIP encryption algorithm was developed for WPA to provide improvements to WEP that could be fielded as firmware upgrades to existing 802.11 devices. The WPA profile also provides optional support for the AES-CCMP algorithm that is the preferred algorithm in 802.11i and WPA2.

WPA Enterprise provides RADIUS based authentication using 802.1x. WPA Personal uses a pre-shared Shared Key (PSK) to establish the security using an 8 to 63 character passphrase. The PSK may also be entered as a 64 character hexadecimal string. Weak PSK passphrases can be broken using off-line dictionary attacks by capturing the messages in the four-way exchange when the client reconnects after being deauthenticated. Wireless suites such as aircrack-ng can crack a weak passphrase in less than a minute. Other WEP/WPA crackers are AirSnort and Auditor Security Collection.[7] Still, WPA Personal is secure when used with ‘good’ passphrases or a full 64-character hexadecimal key.

There is information, however, that Erik Tews (the man who created the fragmentation attack against WEP) is going to reveal a way of breaking the WPA TKIP implementation at Tokyo's PacSec security conference in November 2008, cracking the encryption on a packet in between 12-15 minutes.[8]

Additions to WPAv1

In addition to WPAv1, TKIP, WIDS and EAP may be added alongside. Also, VPN-networks (non-continous secure network connections) may be set-up under the 802.11-standard. VPN implementations include PPTP, L2TP, IPSec and SSH. However, this extra layer of security may also be cracked with tools such as Anger, Deceit and Ettercap for PPTP[9]; and ike-scan, IKEProbe, ipsectrace, and IKEcrack for IPSec-connections.

TKIP
Main article: Temporal Key Integrity Protocol

This stands for Temporal Key Integrity Protocol and the acronym is pronounced as tee-kip. This is part of the IEEE 802.11i standard. TKIP implements per-packet key mixing with a re-keying system and also provides a message integrity check. These avoid the problems of WEP.

EAP

The WPA-improvement over the IEEE 802.1X standard already improved the authentication and authorization for access of wireless and wired LANs. In addition to this, extra measures such as the Extensible Authentication Protocol (EAP) have initiated an even greater amount of security. This, as EAP uses a central authentication server. Unfortunately, during 2002 a Maryland professor discovered some shortcomings [citation needed]. Over the next few years these shortcomings were addressed with the use of TLS and other enhancements [citation needed]. This new version of EAP is now called Extended EAP and is available in several versions; these include: EAP-MD5, PEAPv0, PEAPv1, EAP-MSCHAPv2, LEAP, EAP-FAST, EAP-TLS, EAP-TTLS, MSCHAv2, EAP-SIM, ...

EAP-versions

EAP-versions include LEAP, PEAP and other EAP's

LEAP

Main article: Lightweight Extensible Authentication Protocol

This stands for the Lightweight Extensible Authentication Protocol. This protocol is based on 802.1X and helps minimize the original security flaws by using WEP and a sophisticated key management system. This EAP-version is safer than EAP-MD5. This also uses MAC address authentication. LEAP is not safe from crackers. THC-LeapCracker can be used to break Cisco’s version of LEAP and be used against computers connected to an access point in the form of a dictionary attack. Anwrap and asleap finally are other crackers capable of breaking LEAP. [10]

PEAP

Main article: Protected Extensible Authentication Protocol

This stands for Protected Extensible Authentication Protocol. This protocol allows for a secure transport of data, passwords, and encryption keys without the need of a certificate server. This was developed by Cisco, Microsoft, and RSA Security.

Other EAPs There are other types of Extensible Authentication Protocol implementations that are based on the EAP framework. The framework that was established supports existing EAP types as well as future authentication methods.[11] EAP-TLS offers very good protection because of its mutual authentication. Both the client and the network are authenticated using certificates and per-session WEP keys.[12] EAP-FAST also offers good protection. EAP-TTLS is an alternative made by Funk Software (unlike most EAP-variations and EAP-TLS, which are all microsoft-material). It is more convenient as one does not need to distribute certificates to users, yet offers slightly less protection than EAP-TLS. [13]

802.11i security

The newest and most rigorous security to implement into WLAN's today is the 802.11i RSN-standard. This full-fledged 802.11i standard (which uses WPAv2) however does require the newest hardware (unlike WPAv1), thus potentially requiring the purchase of new equipment. This new hardware required may be either AES-WRAP (an early version of 802.11i) or the newer and better AES-CCMP-equipment. One should make sure one needs WRAP or CCMP-equipment, as the 2 hardware standards are not compatible.

WPAv2

Main article: IEEE 802.11i

WPA2 is a WiFi Alliance branded version of the final 802.11i standard.[14] The primary enhancement over WPA is the inclusion of the AES-CCMP algorithm as a mandatory feature. Both WPA and WPA2 support EAP authentication methods using RADIUS servers and preshared key (PSK).

Additions to WPAv2

Unlike 802.1X, 802.11i already has most other additional security-services such as TKIP, PKI, ... Just as with WPAv1, WPAv2 may work in cooperation with EAP and a WIDS

WAPI

Main article: WLAN Authentication and Privacy Infrastructure

This stands for WLAN Authentication and Privacy Infrastructure. This is a wireless security standard defined by the Chinese government.

Smart cards, USB tokens, and software tokens

This is a very high form of security. When combined with some server software, the hardware or software card or token will use its internal identity code combined with a user entered PIN to create a powerful algorithm that will very frequently generate a new encryption code. The server will be time synced to the card or token. This is a very secure way to conduct wireless transmissions. Companies in this area make USB tokens, software tokens, and smart cards. They even make hardware versions that double as an employee picture badge. Currently the safest security measures are the smart cards / USB tokens. However, these are expensive. The next safest methods are WPA2 or WPA with a RADIUS server. Any one of the three will provide a good base foundation for security. The third item on the list is to educate both employees and contractors on security risks and personal preventive measures. It is also IT's task to keep the company workers' knowledge base up-to-date on any new dangers that they should be cautious about. If the employees are educated, there will be a much lower chance that anyone will accidentally cause a breach in security by not locking down their laptop or bring in a wide open home access point to extend their mobile range. Employees need to be made aware that company laptop security extends to outside of their site walls as well. This includes places such as coffee houses where workers can be at their most vulnerable. The last item on the list deals with 24/7 active defense measures to ensure that the company network is secure and compliant. This can take the form of regularly looking at access point, server, and firewall logs to try to detect any unusual activity. For instance, if any large files went through an access point in the early hours of the morning, a serious investigation into the incident would be called for. There are a number of software and hardware devices that can be used to supplement the usual logs and usual other safety measures.

RF shielding

It’s practical in some cases to apply specialized wall paint and window film to a room or building to significantly attenuate wireless signals, which keeps the signals from propagating outside a facility. This can significantly improve wireless security because it’s difficult for hackers to receive the signals beyond the controlled area of an enterprise, such as within parking lots.[15]

Network encryption cracking

Further information: Network encryption cracking

Despite security measures as encryption, hackers may still be able to crack them. This is done using several techniques and tools. An overview of them can be found at the Network encryption cracking article, to understand what we are dealing with. Understanding the mindset/techniques of the hacker allows one to better protect his system.

Mobile devices and wireless IPS

With increasing number of mobile devices with 802.1x interfaces, security of such mobile devices becomes a concern. While open standards such as Kismet are targeted towards securing laptops,[16] access points solutions should extend towards covering mobile devices also. Host based solutions for mobile handsets and PDA's with 802.1x interface.

Security within mobile devices fall under three categories:

  1. Protecting against ad-hoc networks
  2. Connecting to rogue access points
  3. Mutual authentication schemes such as WPA2 as described above

Wireless IPS alone does not guarantee complete security on a device. It is a part of a bigger solution.

Implementing network encryption

In order to implement 802.11i, one must first make sure both that the router/access point(s), as well as all client devices are indeed equipped to support the network encryption. If this is done, a server such as RADIUS, ADS, NDS, or LDAP needs to be integrated. This server can be a computer on the local network, an access point / router with integrated authentication server, or a remote server. AP's/routers with integrated authentication servers are often very expensive and specifically an option for commercial usage like hot spots. Hosted 802.1X servers via the Internet require a monthly fee; running a private server is free yet has the disadvantage that one must set it up and that the server needs to be on continuously [17]

To set up a server, server and client software must be installed. Server software required is a enterprise authentication server such as RADIUS, ADS, NDS, or LDAP. The required software can be picked from various suppliers as Microsoft, Cisco, Funk Software, Meetinghouse Data, and from some open-source projects. Software includes:

Client software comes built-in with Windows XP and may be integrated into other OS's using any of following software:

RADIUS

Main article: RADIUS

This stands for Remote Authentication Dial In User Service. This is an AAA (authentication, authorization and accounting) protocol used for remote network access. This service provides an excellent weapon against crackers. RADIUS was originally proprietary but was later published under ISOC documents RFC 2138 and RFC 2139. The idea is to have an inside server act as a gatekeeper through the use of verifying identities through a username and password that is already pre-determined by the user. A RADIUS server can also be configured to enforce user policies and restrictions as well as recording accounting information such as time connected for billing purposes.

See also

References

  1. ^ "Network Security Tips". Linksys. Retrieved 2008-02-06. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  2. ^ "How to: Define Wireless Network Security Policies". Retrieved 2008-10-09.
  3. ^ "Wireless Security Primer (Part II)". windowsecurity.com. Retrieved 2008-04-27.
  4. ^ "SMAC 2.0 MAC Address Changer". klcconsulting.com. Retrieved 2008-03-17.
  5. ^ Lisa Phifer. "The Caffe Latte Attack: How It Works—and How to Block It". wi-fiplanet.com. Retrieved 2008-03-21.
  6. ^ "Caffé Latte with a Free Topping of Cracked WEP". airtightnetworks.com. Retrieved 2008-03-21.
  7. ^ Hacking Wireless Networks for Dummies
  8. ^ Robert McMillan. "Once thought safe, WPA Wi-Fi encryption is cracked". IDG. Retrieved 2008-11-06. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  9. ^ Kevin Beaver, Peter T. Davis, Devin K. Akin. "Hacking Wireless Networks For Dummies". Retrieved 2009-02-09.{{cite web}}: CS1 maint: multiple names: authors list (link)
  10. ^ Hacking Wireless Networks for Dummies
  11. ^ "Extensible Authentication Protocol Overview". Microsoft TechNet. Retrieved 2008-10-02. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  12. ^ Joshua Bardwell (2005). CWNA Official Study Guide (Third ed.). McGraw-Hill. p. 435. ISBN 0072255382. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  13. ^ George Ou. "Ultimate wireless security guide: A primer on Cisco EAP-FAST authentication". TechRepublic. Retrieved 2008-10-02. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  14. ^ "Wi-Fi Protected Access". Wi-Fi Alliance. Retrieved 2008-02-06. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  15. ^ "How to: Improve Wireless Security with Shielding". Retrieved 2008-10-09.
  16. ^ "What is Kismet?". kismetwireless.net. Retrieved 2008-02-06.
  17. ^ Wireless Networks, Hacks and Mods for Dummies
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