Charities and police have warned that computer hackers are able to watch victims through their laptop webcams.
The practice - known as 'Ratting' (for 'Remote Administration Tool') - is a variation of standard virus or malware attacks which have affected computers for decades.
By coaxing users to install malicious software on their computers, hackers are able to access video feeds from any webcam without the user knowing that they're watching.
The phenomenon was detailed in an extensive investigation by Ars Technica earlier this year, and now BBC 5 Live has produced its own report, which includes calls by British police and charities for users to be more vigilant.
The BBC report quotes Rachel Hyndman, a 20-year-old student who says hackers may have watched her while she watched a DVD in the bath. She says her webcam was switched on without her knowledge while the computer was (presumably) safely placed away from the water.
Hyndman said in the report: "I was sitting in the bath, trying to relax, and suddenly someone potentially has access to me in this incredibly private moment and it's horrifying.
"To have it happen to you without your consent is horribly violating."
The BBC report also detailed how access to compromised computers is bought and sold online - $1 for a woman's webcam, or a single cent for access to a man's machine - and also quotes a hacker who said he did it for a "laugh".
He told the BBC:
"The risk of getting caught, that someone would do something about you trolling people, isn't that much. It's just a bit of a laugh"
Chief executive of Childnet International Will Gardner said that while such attacks may not be "commonplace", they do happen - and that computer users should learn to take precautions. Those include installing anti-virus software and even covering up a webcam when not in use.
An Association of Chief Police Officers representative told the BBC that accessing webcams without permission is illegal, and would be prosecuted wherever possible.
The Japanese government counter-terrorism practice of <a href="http://www.reuters.com/article/2007/11/20/us-japan-fingerprinting-idUST23858020071120" target="_hplink">fingerprinting foreigners who enter the country</a> may have inspired Doctor Tsutomu Matsumoto to invent "fingerprinting gels", a way of <a href="http://cryptome.org/gummy.htm" target="_hplink">faking fingerprints for scanners</a>. <a href="http://www.dansdata.com/uareu.htm" target="_hplink">Learn how</a> to make your own here.
White Noise Generator
Worried someone around you is <a href="http://articles.businessinsider.com/2011-07-28/strategy/29998051_1_bank-employee-consent-conversation" target="_hplink">secretly recording everything you do?</a> No fear! There's a relatively low-tech way to defeat such snoops, via white-noise-producing <a href="http://www.amazon.com/Productive-Home-Security-Prducts-Jammer/dp/B002PJ7PYS" target="_hplink">audio jammers</a>. These tiny devices use white noise to blur the sound picked up by hidden microphones and other surreptitious recording devices.
Hidden cameras got you down? Blind them all with a simple baseball cap lined with infrared LEDs. <a href="http://creator.wonderhowto.com/amiehold/" target="_hplink">Amie, a hacker on WonderHowTo</a>, shows the world <a href="http://mods-n-hacks.wonderhowto.com/how-to/make-infrared-mask-hide-your-face-from-cameras-201280/#" target="_hplink">how to make one</a>, while <a href="http://translate.google.com/translate?u=http%3A%2F%2Fwww.oberwelt.de%2Fprojects%2F2008%2FFilo%2520art.htm&langpair=de%7Cen&hl=en&ie=UTF8" target="_hplink">this German art exhibition</a> lays out how these ingenious devices work.
These receivers reveal the telltale electronic crackle of hidden mics and cameras. Strangely enough, they were around long before "surveillance culture" became a <a href="http://digitalcommons.law.yale.edu/ylsspps_papers/64/" target="_hplink">common phrase</a>. Today they're sold in all sorts of <a href="http://www.gadget-playground.com/bug-detection.html" target="_hplink">shops for surveillance paranoids</a>.
Sometimes hiding your face isn't enough; sometimes you don't want to be seen at all. For those days, there's camera maps. The <a href="http://www.mediaeater.com/cameras/locations.html " target="_hplink">NYC Surveillance Camera Project</a> in the US is currently working to document the location of and working status of every security camera in New York City. <a href="http://bigbrotheriswatching.co.uk/Anpr_Camera_Locations.html" target="_blank">A similar project</a> is also in progress in the UK.
Credit to artist <a href="http://ahprojects.com/" target="_hplink">Adam Harvey</a> for this one. Inspired by the <a href="http://www.bobolinkbooks.com/Camoupedia/DazzleCamouflage.html" target="_hplink">"dazzle camouflage" </a>used on submarines and warships during World War I, he designed a series of face paint principles meant to fool the facial recognition schemas of security cameras. Check out <a href="http://dismagazine.com/dystopia/evolved-lifestyles/8115/anti-surveillance-how-to-hide-from-machines/ " target="_hplink">The Perilous Glamour of Life Under Surveillance</a> for some tips on designing your own camera-fooling face paint.
Disposable mobile phones <a href="http://www.amazon.co.uk/Pre-Pay-Mobile-Phones-Communication/s?ie=UTF8&page=1&rh=n%3A10394961" target="_blank">are more expensive than you think</a>, but they don't require personal information when you sign up.
Radio-Frequency Identification (RFID) chips are now <a href="http://electronics.howstuffworks.com/gadgets/high-tech-gadgets/rfid.htm" target="_hplink">regularly implanted</a> in passports, ID cards, credit cards and travel papers. These tiny chips make machine-reading your documents easier -- but could also let anyone with the right type of scanner <a href="http://articles.cnn.com/2006-07-10/tech/rfid_1_rfid-industry-rfid-journal-rfid-chips?_s=PM:TECH " target="_hplink">scrape your information <em>and</em> track your whereabouts</a>. Luckily, gadget geeks have come to the rescue again, this time with<a href="http://www.thinkgeek.com/product/8cdd/" target="_hplink"> RFID-blocking wallets</a>. These wallets create a Faraday cage around your items, keeping their data secure until you take them out to be scanned where they're supposed to be scanned. Destroying the chip is simpler: <a href="http://www.instructables.com/id/How-to-blockkill-RFID-chips/" target="_hplink">just nuke it in the microwave for five seconds</a>. Of course, whatever you're microwaving might <a href="http://www.youtube.com/watch?v=4_5UYcyO3Pg" target="_hplink">burst into flames</a> first...
The progress of the government's so-called 'Snooper's Charter' is currently stalled in Parliament, but using Skype may be a way to avoid officials tracking your phone calls. <a href="http://www.techweekeurope.co.uk/comment/how-to-avoid-gchq-snooping-use-skype-71410">Tech Week Europe suggests that Skype users have less cause to be worried about their data</a> being intercepted. The reasons are pretty technical, and any system is fallible, but it may be worth looking into.