Empty cans of Pringles crisps could be helping malicious hackers spot wireless networks that are open to attack.
Security company i-sec has demonstrated that a directional antenna made with a Pringles can significantly improves the chances of finding the wireless computer networks being used in London's financial district.
An informal survey carried out by i-sec using the homemade antenna has found that over two-thirds of networks were doing nothing to protect themselves.
The security firm said all the companies at risk could easily thwart anyone that wanted to find and penetrate their network by making a few simple changes to the hardware used to build the wireless networks.
People have made these antenna out of Pringles tubes, coffee cans and even old satellite dishes
In November last year BBC News Online was shown just how easy it is to find and gain information about wireless networks.
These networks are rapidly becoming popular because they are cheap, easy to set up and replace the unsightly cables that many companies have used to link PCs together into networks.
But the convenience of using radio waves to transfer data between machines is not without its risks.
Many curious hackers have started carrying out so-called war-driving expeditions.
US security expert Peter Shipley invented the practice. It involves driving around an area using a laptop fitted with a wireless network card to find and map out the networks.
Wireless, or WiFi, networks have an encryption system built in, but it is not turned on when the basic hardware of the network is set up.
Pringles tube works as an antenna
Geoff Davies, managing director of i-sec, said its informal survey revealed that 67% of the networks it found had this encryption system turned off.
"Many companies are going out and buying a wireless access point to see what it can do," said Mr Davies. "The problem is that they have opened a great big back door into their network."
He said that i-sec had boosted the chance of spotting networks by converting an empty can of Pringles into a directional, or Yagi, antenna. Plans to make such an antenna first appeared on the net last year.
Properly made, such an antenna can boost signal strengths by up to 15 decibels, vastly aiding the discovery of wireless networks.
Potential for havoc
Disable broadcasting on network hubs
Don't give the network a name that identifies your company
Move wireless hubs away from windows
Use the built-in encryption
Disable the features you don't use
Put a firewall between the wireless network and other company computers
Regularly test wireless network security
In one 30-minute journey using the Pringles can antenna, witnessed by BBC News Online, i-sec managed to find almost 60 wireless networks.
"People have made these antennae out of Pringles tubes, coffee cans and even old satellite dishes," said Mr Davies.
"Those doing [war-driving] are not necessarily looking to take down corporate networks, they are looking to use corporate bandwidth," said Mr Davies.
"But if they are doing that then someone with more nefarious purpose could wreak havoc."
Mr Davies said that a few basic steps such as changing default names, moving wireless access points to the centre of a building and switching off the networks' broadcast functions could help significantly improve the security of these systems.