To install or not install an application - what are the pros and cons?

With the advent of USB devices, many applications that once require an installation process for deployment have been converted to run without one so that the user can use that program directly from the USB device on any machine and a large collection of them can be found here mostly utilizing their portable application framework.

Other program, such as TrueCrypt or its replacement VeraCrypt offers a much simpler model; it simply offers you a way to extract the files into a directory and one can execute the program from there.

I have been a fan of this convenient deployment model for a long time and in particular of avoiding any impact on the underlying operating system. It is particularly helpful in troubleshooting without the need to install anything. Just run!

However, recently I have been having second thoughts whether the benefits of this model is worth the risk of allowing malicious attacker to contaminate the program to do harm? When needing to a USB device in an environment that I do not know its sanity, I always probe it using tools carried by locked SD-Card. In this way, I am protected from being a carrier of attacks or being attacked.

Going back to the history of Windows beginning in Windows 2000 (aka NT5), Microsoft has been using the profile to define a set of file and registry security templates to protect executables and key information, although much of the good intention was discarded in favour of convenience and ignorance. Microsoft had to do something to rein in the unruly behaviour by introducing the UAC in Vista to the dismay of large unappreciative community.

Apart from other benefits, the main aim of the file system security is to protect key files from bring modify by user without administrative privilege. From Vista onwards, all applications run by default with standard user privilege and that means that they cannot make changes to program files or protected areas. This is a good thing and has improved the security of Windows a lot.

Now if instead of installing a program that requires administrative rights to carry out and deployed into designated protected areas, we modify the deployment model of the program to allow it to run from anywhere, doesn't such a practice is a throwback to the good old days of NT4/5/XP (run everything in admin account) style? Aren't we then essentially turning the file system protection off for these programs? Aren't we making our programs more vulnerable to attacks?

What caused me to ponder is my latest installation of VeraCrypt 1.16 that has fixed a couple of recently discovered critical vulnerabilities. In the past I have been using TrueCrypt in portable mode without installation. Then I wonder: wouldn't this mode of deployment makes it easier for others to attack the program or to use this program or this type of program, running at elevated privilege, to launch attacks?

In the end, I decided to install the program. What is your opinion on this issues?

In Linux, by default it does not allow programs to run from removable devices.