Cyber Security: Network security challenges

       

Internet routers are designed to move datagrams to their destination but how secure are they?

They have been designed to move datagrams to their destination and have been programmed with strategies to overcome problems such as congestion or the failure of a part of the network. These strategies involve re-routing datagrams via any alternative direction. Therefore, it is impossible to state with any assurance which route will be taken by a datagram travelling outside a local network.

The datagram may travel directly, or, more probably, travel through several routers located anywhere in the world. These routers will most probably not belong to either the sender or the recipient, but a third party. In most cases this will not matter, but datagrams can be copied, and their security compromised, as they pass through a router without alerting either the sender or receiver.

The process is known as packet sniffing and it has many legitimate purposes including analysing network performance and for law enforcement, but packet sniffing software is readily available to anyone who chooses to use it. In the past, packet sniffing required a computer that was wired to the network, but wireless networking means this is no longer the case.
               
Security risks of wireless networking
Since wireless networks transmit data over a medium that is shared by everyone, anyone with a compatible receiver or transceiver is able to eavesdrop on the radio signals being sent.

Ensuring that the eavesdropper is not able to convert these signals into the original message is a desirable security property of any wireless network, referred to as ensuring confidentiality. (This was one of the three security essentials we mentioned earlier, along with integrity and availability.)

Another security problem with using a shared medium for transmission is that malicious users could interpose themselves between a sender and a receiver and modify the messages being exchanged or even destroy them entirely. This is sometimes called a ‘man-in-the-middle attack’, and it compromises the integrity of the data being transmitted across the network.

  

Finally, an attacker could transmit lots of random data on the frequency being used by the wireless network, congesting the network and thus preventing other users from sending data. As we saw earlier in the course, this is called a ‘denial of service’ (DoS) attack and is an example of an attack on the availability of the network.

How encryption can help
So how do wireless networks address these potential security issues?
One commonly used security mechanism is encryption, which can help to ensure both the confidentiality and the integrity of data. The idea of encryption is to take the information you wish to protect and transform it into a different form, such that only the people who are supposed to receive the information are able to reverse the transformation and recover the original information. This is like having a key to unlock a door; only a person with the right key can open it.

Encryption can help ensure:

• Confidentiality – When a message is encrypted using a particular key, it can only be decrypted to recover the original information if the same key is used. This ensures that messages are confidential between the sender and the receiver.
• Integrity – Encryption can prevent messages from being modified without the receiver’s knowledge.
• Authentication – Encryption can contribute to the process of proving the identities of the sender and receiver.

© The Open University