Talk:End-user Computer Security/Main content/What to do when you discover your computer has been hacked

Book-section relative link not possible for icon in heading
When this book is finally published, the link set for the heading "When to change digital passwords and keys?" should be converted into an icon-based absolute-address link (or perhaps a link that uses the "Wikibooks:" prefix [using such prefix still results, in some respects, in an absolute address]). Unfortunately, relative links for images (such as icons), do not seem possible, which would have been ideal.

The current method of linking is something of a temporary workaround. It has the disadvantage of somewhat ruining the visual aesthetics on the page.

When this book is finally published in its permanent address location, the absolute link set in the heading "When to change digital passwords and keys?" will need to be accordingly updated.

A text-based link is now being used such that a relative URL is being used, meaning that there are no concerns when moving this book to a different location.

MarkJFernandes (discuss • contribs) 15:22, 21 May 2020 (UTC) 

Add information about using a Faraday cage/shield with a potentially security-compromised computer?
A Faraday cage/shield can be used to shield unwanted EM communications from and to your computer, such communications perhaps arising due to malware or other kinds of hacking. This sounds like worthwhile information to add to this chapter somewhere.

Electrical conductors are used in Faraday shields. Metal is such a conductor and specifically, aluminium foil has been used for such shields (in respect of RFID blocking for mobile phones).

A potentially cheap solution, that also might not require purchasing anything new, for building a Faraday shield for a computing device such that you can still use the device whilst the shield is on, is as follows:


 * 1) Take your computer with you into a metal car.
 * 2) Shut all the openings of the car.
 * 3) Add foil to cover-up those window areas where radio signals can get through.
 * 4) Then use the computing device in the car.

Hopefully, Bluetooth and WiFi will be blocked by doing these things, during your use of the computing device in the car. The just striked-through idea is unlikely to work since slight gaps in metal shielding cause such shielding to fail.

Perhaps a cheap alternative is to use an emergency thermal metallic disposable sleeping bag. You can place your laptop in the bag, and then have the bag extend over your head and at least such that it covers part of your body. Most likely, radio signals would be blocked by taking such measures. Again, this idea is unlikely to work because gaps in metallic shielding cause shielding to fail. Metal apparently reflects RF communications, and in some cases, it seems it has the potential of increasing signal strength rather than decreasing it. If this idea were modified so as to include saline water, perhaps saline water in a foot bath, with the computer user covered in the sleeping bag from head to toe, and with their feet in the foot-bath water, then perhaps this idea might work. The saline water apparently absorbs RF radiation instead of reflecting it. In fact, this attribute of saline water can probably be used in the drawing-up of other solutions to this general problem.

Using a foil emergency thermal tent may provide a cheap way to construct a Faraday cage/shield in which a hacked PC can be 'safely' used (without having to worry about successful EM communications being performed by malware on the hacked device). Their inexpensiveness is derived from the fact that they can be very cheap to buy. Worrying about MITM attacks to the material perhaps is unnecessary because tests can be performed when the tent arrives to confirm that the material is sound. Gaps in the tent might cause the shield to fail. In this respect, using aluminium tape to tape up the gaps might be a good idea although doing so might cause breathing problems to those in the tent.

Alternatively, using transparent or semi-transparent shielding material might allow the construction of a Faraday cage/shield, where only the PC needs to be inside the cage/shield (because users can see through the material to see keyboard keys and the VDU). Such materials may be mesh materials such as a copper-mesh material. See here for more information on such materials.

A variation on this, is to use EM absorbers rather than reflectors, at least for part of the shield's function. It would seem that such shields wouldn't then be called Faraday shields, but they would still be effective shields for some kinds of EM radiation. Saline water is apparently an EM absorber (due to its electrical conductivity), conveniently is also transparent, and is also cheap, meaning that it can perhaps act as an EM-shield screen filter allowing the seeing of a computer's screen whilst at the same time filtering out RF emissions, at a low price point. Getting a suitable container for the liquid is perhaps not so straight-forward: the container must not let out water, and for laptops without an external keyboard, must leave enough room to be able to use the laptop's integrated keyboard. An A4 clear pencil case might be such a suitable container and also quite cheap. If there are concerns about it leaking, perhaps thorough leak-detection testing, the use of water-proofing sealants, and the precautionary additional use of protective water-resistant computer covers, can go some way towards allaying such concerns. Also the conductive gel used for things like ultrasounds, perhaps can also be used for shielding the screen area such that you can still see the screen (again using the EM absorption principle). Such gel can be very cheap to buy, and apparently you can even easily make your own DIY gel&mdash;see here. Have tried DIY gel using Aloe Vera hand-wash with salt. Does work to block cellphone signal but quite a bit of salt needs to be added and when mixed with hand-wash, the hand-wash turns cloudy, so doesn't appear suitable (because no longer transparent nor translucent). Have also tried with saline water, and saline water does work (for cellphone signals); again, quite a bit of salt is needed. Have successfully used Dr Oetker gelatine, mixed with salt and water, to create a firm transparent gelatine layer through which one can easily see a smartphone screen, and that shields mobile-phone signals (and presumably also Bluetooth and WiFi). Such gelatine may already be available in a user's cooking cupboard, but even if it has to be bought, the cost of it in respect of the amount required for the shielding, is quite low. Being able to use it on a partly upright large computer screen is perhaps tricky. What is maybe needed, is some kind of transparent see-through plastic mould big enough to fit over such screens, for holding the gelatine. It appears that if the gelatine is too firm, the shielding doesn't work, probably because the conductivity is then not strong enough&mdash;water conductivity apparently isn't so much present when the water is solid (like ice). Bought ¼ litre bottle of Aquasonic 100 Ultrasound Transmission gel produced by Parker Laboratories Inc. from Amazon, at the low price of £3.95. The gel indeed shields a mobile-phone signal, is usefully clear, and also usefully firm. However, the gel is lumpy, such that when you look through it at a computer screen, what you see is mostly too distorted. Have tried to liquidify the gel so that it can be set without there being any lumps, but without success. I tried microwaving it, as well as thinning down a diluted solution of the gel with water, but all to no avail. Simply thinly "painting" the gel (such that there aren't any significant lumps) also doesn't seem to work&mdash; perhaps the barrier must have a thickness greater than simply a thin layer? Melting the gel using conventional heating methods (such as over a stove), might be more successful in melting the gel, such that when the gel is later cooled down, depending upon the container, it is able to be set without any lumps. If such melting and setting is possible, then perhaps a glass pane, maybe one from or even within a photo frame, can be re-purposed to construct the suitable transparent container for the gel setting. Have successfully pinned Ultrasound gel between two transparent materials, such that distortions caused by lumps in the gel disappear. However, a new issue has now been brought to light, and that is the presence of bubbles in the gel, even after such pinning, such that the shield fails because of the lack of protection at the locations of the bubbles due to their too large sizes. Have tried heating-up the gel to see whether the heating-up process might get rid of such bubbles, but found it to be ineffective. Have also tried diluting the gel, and then progressively thinning it back to its original consistency, to see whether that might get rid of the bubbles. That too didn't work. Might be possible to get rid of the bubbles if the gel is thinned to more of a watery state and used in that state but then there's the issue of leakages due to the lower viscosity of the material. Such measures might pan out as a workable solution but more investment would first need to be made in the area of preventing leaks in the container. Another solution to such issues, is probably to pin the gel between two sheets such that there is a fairly thick space between the sheets, in such fashion that the sizes of yielded bubbles are too small and hopefully not clustered enough, to cause the EM shielding to fail. Perhaps a novel way to construct an "RF absorbing gel/water" container that is used over a screen in order to shield the screen in such fashion that the screen still remains visible to users, is to use double-glazed windows for the container. The top of the windows would be sawed-off, and the water/gel would then be poured into the gap(s) of the double-glazing. Double-glazed windows appear to be available at low prices. Also, old windows, that might be otherwise thrown on the scrap heap, might be available at even lower prices (perhaps even given away for free). Information on Wikihow about how to make a Faraday cage can be found here. In particular, the Wikihow information indicates that having layers in the shielding such that the layering alternates between electrical insulation and electrical conduction, results in stronger shielding. Also another thing to consider, is that when choosing conductors, using materials with higher electrical conductivity will likely result in stronger shielding&mdash;see here for a table comparing the conductivity of different materials.

Useful comparison of different RF shielding techniques: https://mosequipment.com/blogs/news/the-results-are-in-video-comparison-of-various-competitors-shielding-effectiveness

Such information is relevant to the Wireless Communications chapter, and perhaps should also be added there (see the note about adding such info on that chapter's discussion page).

Can sell computer for spare parts, in the situation that you are unable to "clean" the entire system (which can help to recoup losses)
If you discover your computer has been hacked, or may have been hacked, you can perhaps sell the computer in order to recoup losses, perhaps in order to finance the purchase of a new system. In the case where you are unable to make sure the system is "clean" prior to selling, you can possibly sell the system in the form of spare parts, in order to avoid the ethical issue of selling on a hacked system (that could represent compromised security for the purchaser of the hacked system).