In theory, is it possible that people use features included in Linux distros as standard to change link locations as they are clicked, and direct people to different websites.

An example of this would be if someone had scraped a website, then changed the information on that website very slightly, then redirected the browser to the changed website, so the person browsing would be given misleading information.

Is this something people using Linux can do (please do not tell people how to do this in any detail; I just want the conceptual underpinnings of it: enough to prove or disprove the theory)?

Update: I am specifically wondering if Linux users can do this to other people's computers remotely.

  • @Anthon good point; I was thinking remotely, but I didn't specify. I'll edit the question to take on board your point. But now that I think about it, if we assume that people can hack into servers then yes, this demonstrates it is theoretically possible... You can submit your comment as an answer if you like. – Peter David Carter Jun 6 '16 at 12:57

If you have access to a computer and are able to replace the standard commands then yes this is possible. It is even dangerous on a shared computer to to include a path to /usr/local/bin before /usr/bin if someone else has access rights.

In such cases or if you are not the only one having root privileges on a machine, you cannot trust any of the software including the webbrowser. You can download the source of the browser and its compiler, change the source, install the 'enhanced' browser. This browser might give you wrong information while certifying that you are looking at what you think you are looking at. Or even simpler replace some bankaccount data with other data when you are doing bank transfers online (including showing you that sent things to the intended person when you ask for an overview of transactions).

You should therefore not do anything sensitive on a computer you don't control.

  • What about on the server? The ISP computer would also be a link one doesn't control, couldn't it? – Peter David Carter Jun 6 '16 at 13:09
  • If you are accessing a page over HTTP, yes, the ISP could change the contents in transit. This is why HTTPS is a good idea - it provides end-to-end encryption. – Nathan Osman Jun 6 '16 at 22:53
  • @NathanOsman Is there no way users circumvent end-to-end encryption of this sort...? – Peter David Carter Jun 7 '16 at 9:06
  • @PeterDavidCarter-Poulsen The server and the ISP are different things. As Nathan indicates with HTTPS (or any other communications using TLS/SSL) the ISP cannot change the content without your noticing (assuming your browser has not been tampered with). There is no feasible way to get in between that but the details for why that is belong more security.stackexchange (i.e. prevention of man-in-the-middle attach by end-to-end encryption) – Anthon Jun 7 '16 at 9:08
  • @Anthon yeah, it's wandering off-topic a bit, so I'll leave the commentary discussion here. Thanks for the info. – Peter David Carter Jun 7 '16 at 9:09

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