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We have seen some tremendous growth in wireless/mobile network usage and its services. They are not only confined to voice services but various data services also for which access to internet are crucial. And with its popularity comes the issue of secure access to these services. It was not an issue when it was first introduced as crackers didn't figure out the ways to make it insecure. But as the time has passed by, cracking methods have advanced as well with the support of some tools and platforms only making it easier to crack into a wireless network. This makes an organization's operations and data transfer compromised. Therefore secured wireless access and data transfer through it is absolutely essential and we will look into the threats which stand in the way. I have focused primarily on security issues regarding Wireless LANs in this paper.
As more and more wireless networks being deployed by the day, security of them is a great concern for an operator. In fact wireless network security is the biggest barrier to the adoption of wireless LANs . Let's identify the aspects for which the security is implemented. They are (1) privacy, (2) authentication, (3) accounting and billing, (4) availability, and (5) reliability . To identify the security problems, analyze them and develop security solutions for them and implement them is the objective of a secured system. It is easier to understand wireless technologies by categorizing them into three layers, as shown below. The three layers are device, physical, and application and service (protocol).
Application and services:
Wireless applications: WAP, i-mode, messaging, VoIP, location-based services.
Wireless standards: 802.11a, 802.11b, 802.11g, AX.25, 3G, CDPD, CDMA, GSM, GPRS, radio, microwave, laser, Bluetooth, 802.15, 802.16, IrDA.
Mobile devices: PDAs, notebooks, cellular phones, pagers, handheld PCs, wearable computers.
In the device layer (mobile devices) are gadgets ranging from the smallest cell phone to PDAs and notebook computers. These devices use wireless technologies to communicate with each other. The physical layer contains different physical encoding mechanisms for wireless communications. Bluetooth, 802.11x, CDMA, GSM, and 3G are different standards that define different methods to physically encode the data for transmission across the airwaves. In this chapter, we will focus on networks built upon the 802.11x and Bluetooth standards. The application and service layer, also referred to as ISO layers 2 to 7, contains the protocols that enable wireless devices to process data in an end-to-end manner.
Protocols like Wireless Application Protocol (WAP), Voice over IP (VoIP), and i-mode reside in this layer .
Now the security threats which are specified for a wireless network can be traced back to the end user in wired network. In order to adopt and implement a secure wireless technology, one needs to,
Understand the capability of current products
Understand the networking needs
Understand the potential risk that are facing
Find a solution tailored to the environment
3.1 Access Control and Authentication:
There are two nodes one needs to know in a wireless network:
Access point (AP)
The STA looks to access the AP to get the wireless connection. The reference monitor grants the STA the access to the AP. For security reasons, it has to be a controlled access to the network to prevent crackers and hackers to access the network. Thus, access control is a form of security where a user makes a request to use or access an object on the network.
Authentication is the method by which the reference monitors determines who actually made the request. The reference monitor must authenticate the channel and determine who the request is from. It is essential for the network security for the same reasons stated above.
3.2 MAC Address Filtering & SSID:
MAC Address Filtering is a scheme that helps in filter the packets going through the networks. i.e. it only allows terminals with certain MAC (Media Access Control) address which is unique to each network interface card on a wired/wireless network to access the network. However, problem with this scheme is that one can sniff for a valid MAC address and with the help of it can access the network.
The SSID (Service Set Identifier) is a token which helps in identifying the wireless LAN (802.11) network. It's a secret key which is set by the network administrator which is mandatory to be known to join the wireless network. However, it too is vulnerable to be discovered by spoofing. On top of it, it is a secret key which creates a key management problem for a network administrator. If the network administrator seeks to lock a user out of the network, the administrator must change the SSID of the network, which requires reconfiguration of every network node. Some 802.11 NICs allow you to configure several SSIDs at one time. And most 802.11 access point vendors allow the use of an SSID of "any" to enable an 802.11 NIC to connect to any 802.11 network. Therefore the idea of solely using SSID as a security mechanism is not advisable .
It's a method of ciphering the data for a secured channel transmission. It protects the data by preventing the hacker from knowing the communicating end-users and eavesdropping. Now, there hasn't been an encryption algorithm which cannot be broken. But what it can do is it can make things difficult while interpreting the data when being analyzed thus making it difficult to break.
3.4 Integration with wired networks:
This creates a challenge while applying services for wireless services in form of routing etc. when a wireless network like an ad-hoc network is to be integrated with a traditional fixed network. Routing itself is a service that has to be secured against misuse and intrusion. In an environment where network topologies are constantly changing, handling the public key infrastructure is one of the key challenges. It is also unclear how security mechanisms for communication like IPsec cooperate with mobile IP and firewalls.
And, there will always be a case where a user's data related to the locations where he/she has been has a possibility of being compromised. Just recently we have seen an app in the i-Phone which tracks the user's location and displays the locations with the help of basic tools and if the phone end's up with an unknown person, he can easily track down where the phone owner has been. This is one example of context-aware applications. There will be other applications making use of personal data to improve their value for users, e.g. travel habits. It is unknown how this data can be protected against misuse.
There are some protocols available which provide either end to end or hop by hop encryption such as IPSec, SSL/TLS etc to provide security, but the new internet protocols tend to create new security problems. We assume that new applications or protocols have to be developed with security in mind from the beginning.
4. Types of Threats:
Security threats to which the Mobile Internet Networks are exposed are due to the growing uncontrolled Internet and peering traffic that contain growing volumes of malicious attacks. High-touch servers can be negatively impacted by Denial of Service (DoS) attacks, worms and malware aimed at critical mobile network infrastructure. Mobile Internet network threats include new forms of compound DoS/DDoS worm attacks that consume huge volumes of bandwidth, while propagating aggressively across mobile networks and subscribers in minutes rather than days. Also one problem which can do harms to a great extent to mobile devices is the low-rate battery draining attack as well exploiting mobile network itself through paging attacks .
Here are some of the most common type of wireless network attacks.
4.1 Denial of Service:
This is perhaps one of the most common type of attack any kind of network faces in which a valid user is denied the services offered by the network as the network resources are occupied by the attacker who continually bombards a targeted AP (Access Point) or network with bogus requests, premature successful connection messages, failure messages, and/or other commands. It actually doesn't expose the data of an organization as it actually prevents data from being transmitted, however the attacks are for a purpose of observing the wireless network recovery when the initial handshake codes are retransmitted by all devices.
This gives an opportunity to the Mallory to note down these handshaking codes and gain unauthorized security access to exploit the weaknesses of the system. When a system is using encryption tool such as WEP (wired equivalent privacy), for which there are tools available to apply different possible keys that can be captured to analyze the recovery.
4.2 Man-in-the-middle attack:
This kind of attack is executed when a hacker logs into a computer which he uses to access the wireless card which can be used to sniff the network traffic. A kind of this type of attack relies on the security faults in challenge and handshake protocols to execute a de-authentication attack. Software's such as LANjack and AirJack can help in execute the step by step process. The most vulnerable to this attack is the wireless hotspot as they are little or no security on these networks .
4.3 MAC spoofing:
Here, the network cracker listens to the network traffic and is able to know the MAC address of that computer which has an access to the network. Even though wireless systems most of the times have the capability of allowing only authorized users with specific MAC IDs to access the network, some software's allow the cracker to pretend it has the desired MAC address and it can fool the network by it and get access to it. The reason why the MAC addresses are compromised is because the end user on the with access to a Wi-Fi network constantly transmits its MAC address on its 802.11 header, which can easily be read by someone not very far from the vicinity of that user with an 802.11 receiver (laptop and wireless adapter) and a freeware wireless packet analyzer. Thus filtering of MAC addresses doesn't help as the host can assume that its network is free from unauthorized access and yet there is one which creates a false since of security.
4.4 Jamming Attacks:
This type of attack can be executed in a Wi-Fi network to disrupt its communication. Here, the attacker floods the Wi-Fi spectrum with powerful signals on the same frequency, which interferes with the communication between the AP and its users. This in turn cuts down the communication between the two. However, the equipment used for executing it is expensive, the result is very temporary, and therefore not a very tractable method of long-term network disruption.
5. The Secured Wireless network:
5.1 Wireless Network Security Elements:
These are some of the steps one can take to help secure their wireless network.
5.1.1 Data protection while transmission:
This is done as mentioned before by encrypting the transmitted data. Even though being a challenge, it's essential, by translating the data into a language which only intended user understands. Encryption requires that both the sender and receiver have a key to decode the transmitted data. The most secure encryption uses very complicated keys, or algorithms, that change regularly to protect data.
5.1.2 Granting access to authorized users:
One of the ways to do it is to give unique login IDs and passwords for authentication. One of the most secured ways of authenticating a user is to authenticate on a per user per session mutual authentication between the user and the service provider. Also prevention of connections through access points which are being detected unprotected and used by the users who are not supposed to use it. These are known as rogue access points, and the majority of these are installed by employees, not malicious intruders. . There are tools that can help, and checking can be done with a wireless laptop and software in a small building or by using a management appliance collecting data from your access points .
5.2 Wireless Network Security Solutions:
Talking about wireless LANs, some solutions are there which help provide encryption and authentication. They are Wi-Fi Protected Access (WPA), Wi-Fi Protected Access 2 (WPA2), and virtual private networking (VPN).They can be applied according to the type of wireless LAN used.
5.2.1 WPA and WPA2:
These standards are certified by the Wi-Fi Alliance providing enterprise solutions. It provides mutual authentication for verifying individual users. The WPA profile also provides optional support for the AES-CCMP algorithm that is the preferred algorithm in 802.11i and WPA2. With WPA2 providing next generation Wi-Fi security, it can support government grade encryption.
It can provide security to the users who are on the road or mobile and want to access the network. The data tunnels through two or more points on a network using encryption so it's protected when being transmitted over unsecured networks such as the public internet.
5.2.3 RF shielding:
Some schemes can be used to prevent the wireless network signals from propagating outside the network premises. This can be very helpful against eavesdropping and it makes it difficult to receive the signals for the hackers. It can be implemented with the help of applying specialized wall paint and window film to a room or building to significantly attenuate wireless signals.
5.3 Practical Steps A User Can Take:
Enable the security features that come with the access points and interface card. It can be done by running a software program that comes with the wireless device.
To use 802.1x to protect your wireless network, set up dynamic WEP with the strongest keys possible (128-bit), use Message Integrity Checksum (MIC) when available, and use client certificates for authentication.
Specify policy for your wireless network: Design different groups and organizational units for access from wireless networks to either intranet or Internet. Enforce a group policy for use of IPSec and 802.1x.
Regularly update the firmware version on the access point which will make the wireless network more secure and reliable.
To maintain a secured wireless network, a network implementer or wireless gear supplier can be considered to maintain and secure a network.
Wireless Networks provide enormous advantages in terms of providing internet with mobility. However, they pose risk as well with the provided opportunity. We looked at the challenges and threats the most common types of wireless networks face and provided some solutions to tackle them. But there is a bottom line which is no matter how advance methods you use to protect your network from unauthorized users, crackers are still able to crack them. Perhaps the most secured way to protect the wireless network is to understand the mindset or the techniques a hacker uses and build your system accordingly.