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22 December 2012 / Others

Practical Wireless Security - Part 2

Application Controls Audit


This is the second part of practical wireless security (much later that promised). Earlier, we saw two key points: choosing the right Wi-Fi and choosing your own DNS. This post continues to give you some more points about securing your wireless browsing 3. Communicate in secret - Use encrypted communication After choosing a well known Wi-Fi and setting your DNS to a well known secure DNS (read Practical Wireless Security - Part 1) you have finally settled down to browsing the Internet. If you are like me, the first thing you would do is check your mail. Assuming you are connecting through your browser, you need to ensure that you are using encrypted communication. So, what then is encrypted communication? Remember the secret messages that you sent in school? You agreed with you friend that ‘A’ will be ‘F’, ‘B’ will be ‘G’ and so on. Once both of you knew what each alphabet represented, you were able to communicate with each other, without anyone ever finding out. The only way they could find out something was if they knew your ‘key’ (A=F, B=G). Encryption in computers works in a similar fashion, except that it is applied to blocks of 0s and 1s. When you type http://www.gmail.com, your computer will form a virtual connection between the gmail server and itself. When you type https://www.gmail.com (notice the additional ‘s’) your computer will not only form a virtual connection, it will form an encrypted connection (keys that both computers understand). This type of connection is called an SSL (secure socket layer) connection. When using free Wi-Fi, or even otherwise, you must ensure that any web page that you connect where you need to enter critical information (passwords, credit card numbers, etc.) is always an SSL enabled website. Check the link for the additional ‘s’. Each browser has different mechanisms to tell us of a secure connection. Internet Explorer has the symbol of a lock that appears for encrypted communication. Safari shows ‘https’ in a gray box that once clicked shows you the ‘SSL certificate’ of the website. What is a certificate? Remember, the ‘key’ that needs to be known to both computers. How do you send it between the two computers using the same connection? This is done by a complex mechanism of certificates and trusted parties that assure us that the website is who says it is. Firefox shows a lock in the field where you enter the website name. Ensure that all sites where you plan to enter critical information is an ‘https’ site and not just a ‘http’ site. Before entering any data, do this check. Do not ignore warnings that say ‘The certificate for this site has expired. Do you still want to continue?’ unless you are sure of the website. 4. Use a personal firewall Your computer is built to be connected to other computers. It needs to keep an ear open to listen to anyone trying to communicate with it. These ears which our computer keeps open are called ‘ports’. Every time you make a valid communication request, one of your ‘ports’ establishes a connection with the other computer ( a connection we encrypted in section 3). There are many malicious entities lurking on the Internet who keep scanning the horizon for open ports. If they find one that is open and is not well protected, they may try to find a way into the computer using that open port. This is where a firewall comes in. A firewall is a computer program that keeps a track of all possible connections that your computer can make. If there is any request to connect to your computers ports, it makes sure that the connection is valid (not anything malicious as far as it knows) and allows the connection. If it finds it suspicious, or if you have specifically told it to not allow a connection, it will block the connection. There are many good free firewalls available. I have always referred to the good people at http://www.techsupportalert.com/best-free-firewall.htm for the latest update on good freeware. Today operating systems too come with their in built firewalls. Both Windows and OSX have in built firewalls that can be used. 5. Update your Anti Virus I assume that you already have an Anti Virus (AV) program in place and that you are smart enough not to stop it. If you do not have a firewall, please stop reading this and get one now. There are many good ones around. One of my favorites is: http://www.kaspersky.com The standard ones of McAfee and Symantec too have good firewalls. Of course, there is the http://www.techsupportalert.com/best-free-anti-virus-software.htm link for those who want a free AV program. An AV program is only as good as the latest update. There are many virus and worms being released into the Internet everyday. The AV companies try to keep a track of it. For every virus they find, they create some sort of mechanism to prevent the virus from attacking the system where their AV is installed. They send these as updates on a daily basis. The software is also configured to get an update from the servers everyday. Your only job is to ensure that it happens. Double click on the AV program and you will easily be able to see the ‘Last update date’. Ensure that the last update is current. Also, read a previous post on password managers (http://practicalinfosec.wordpress.com/2012/10/18/password_managers/) to have secure passwords for your online accounts. These tricks should give you a reasonable amount of security. Remember that you still will not be 100% secure, but you now know a few tricks for a more secure free Wi-Fi experience. Google Wi-Fi security and you will find a lot of good reading material to improve your security further.