Disabling Security Cameras with Lasers

There's a really interesting video of protesters in Hong Kong using some sort of laser to disable security cameras. I know nothing more about the technologies involved.

EDITED TO ADD (8/14): LIDAR from self-driving cars has damaged security cameras before.

Posted on August 2, 2019 at 11:53 AM • 14 Comments

Comments

JSPAugust 2, 2019 12:48 PM

Video cameras dynamically adjust shutter and aperture to control the lighting conditions. Lasers can easily mess this up and the imagery ends up being underexposed, practically all dark.

Some celebrities have been known to wear special clothing with reflective striping to disturb cameras. Use your search engine of preference to look for "anti-paparazzi clothing" if you're interested. The principle is the same.

Some AnonAugust 2, 2019 1:18 PM

Ordinary keyring laser pointers have a power output of 1-5 milliwatts. That's enough to see the dot on a projector screen, and to confuse a camera's autoexposure system, but not enough to be a huge eye danger (your blink reflex is fast enough to protect you so long as you don't stare into the beam) or to cause permanent damage to the camera. The camera will get its bearings again when the laser isn't shining into its lens anymore.

There are high-powered laser pointers, of 100 mW or more. They're restricted in many jurisdictions but still widely available, since they look much like ordinary pointers or flashlights. Those are powerful enough to do permanent damage to the image sensor in a camera, and are what I'd be using if I were such a protester.

WilliamAugust 2, 2019 2:17 PM

Yes, the light of the laser throws the camera's white balance off. I believe this is why some security cameras have mirrored dome covers in order to deflect these sorts of attacks.

RobertAugust 2, 2019 2:44 PM

@William, I may be wrong, but I've always assumed that the reason some camera domes are mirrored is so that one can't tell which direction the camera is watching. Or even if there's a camera in there.

@Schneier I suspect the issue here isn't lasers, it's the chips used by modern digital cameras. Note this article https://www.metacafe.com/watch/1392382/invisible_mask/

vas pupAugust 2, 2019 2:47 PM

@William. Yeah, and pilots have special glasses (rather glasses with special lenses for the same purpose.

Clive RobinsonAugust 2, 2019 6:05 PM

@ All,

We have discused this in the past at various times on this blog.

One way to "jam" a camera is with two semiconductor lasers one red one green. You don't collimate to burn the sensor, but to confuse the sensor system.

With cheap cameras especially the "low light black and white" they don't have IR filters over the sensor so an IR laser can "white out" the image with little difficulty.

The cameras that are most susceptible to attack are the "night vision" type that actually use IR spot lights past experience has taught me not only are they quite fragile they are also quite expensive.

Oddly whilst you can buy systems to protect CCTV cameras from such attacks it appears nobody realy wanted to buy them outside of the military...

Something tells me that after this, police forces will be holding out their hand to those who have a hold on the public purse strings...

Petre Peter August 3, 2019 7:29 AM

It's a risky attack to pull off because there is no confirmation of the camera being jammed.

Clive RobinsonAugust 3, 2019 8:39 AM

@ Petre Peter,

It's a risky attack to pull off because there is no confirmation of the camera being jammed.

Not so much as you might think.

You need your laser to be as close to the "bore sight" as posible, and within the frequency spectrum used for the AGC signal that does the white balance.

As the AGC is more linear than logrithmic you can work out how much power you need to move the rest of the image out of the linear region.

The maths is actually not that dificult to work out, or you can go look up the antenna gain path loss calculations and use those.

Tom J NowellAugust 6, 2019 1:13 PM

You can buy strong blue laser pens that can burn out the CCD sensors in cameras in the ladies market, anybody in HK who wants want can just get the MTR to Mong Kok and buy one there or in the nearby electronics stores. They're on Ebay too

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