This is a guest post by Richard Clinker. Richard has been in the IT industry for 15+ years working with systems running ATM networks and internet banking in an operations role. For at least ten of those years, he has been a Free and Open Source Software user and advocate. Most of Richard’s knowledge of security matters has come from his interest in FOSS. Having been enabled by free software to really understand the systems he ‘plays’ with has made it far easier to gain an insight into their security.
A friend of mine recently asked me to do a little light penetration testing for him. He’d managed to establish what his smartphone’s IP address was and wanted to establish how visible it was on the internet in terms of any open ports. In my opinion this is a good, basic indication of a device’s security. Also, once you’ve established a ‘baseline’ of what ports (if any) are visible it could provide an indication that a device had been compromised; If unexpected ports suddenly appear to be open/in use, it would be very much worth establishing if the cause is a malware ‘infection’.
To establish what my friends phone looked like to other networked devices, I started by trying to glean information about it using various nmap scans. This proved pretty fruitless. Following this up with a much more basic attempt to merely ping the IP address provided proved that his phone was basically not visible at all! As anyone who runs a machine with services visible to the internet will appreciate, a device that is ‘stealthed’ in this manner is fairly certainly secure. Attempted attacks on open ports are not uncommon!
An altogether simpler way of establishing how visible your devices and local networks are is to use a tool along the lines of Shields Up by Gibson Research Corporation. I used this very useful tool to check my phone’s ‘footprint’ and got similar, re-assuring results to my testing on my friend’s device. Stealthed.
In conclusion, a lot of emphasis is put on making sure people run ‘internet security suite’ applications and so-on. However, a little knowledge and practice in using some pretty simple tools can provide a very useful indication of your current cyber security and serve as an indication of problems if unexpected results are seen. Happy hacking!