Emsisoft Emergency Kit
https://www.emsisoft.com/en/home/emergencykit/
The good thing about EEK is that it’s a portable program and uses no resources unless you actually run it.
Exactly, thanks Bob. 
I can recommend it as a second opinion scanner.
I just gave this a quick whirl given that it doesn’t use resources until it is run, but running the downloaded file wants to ‘Install’. That isn’t what I expected, I was expecting a portable no install required, just run the file.
So I stopped at that point.
Hi Dave, in this case it isn’t really installing but rather copying files to a given location.
To remove it, simply delete the folder. Nothing is placed anywhere else except in that folder.
It is just the confusion in calling it a portable app, for me that is being able to run it from a single file, be that on a USB stick or in my case the location where all of my portable apps are located and in the Security sub-folder as it is a security app.
It defaults to C:\EEK. I don’t know if that’s changeable at installation. I didn’t try that.
There appears to be that option, see the attached image in my Reply #3.
In that case, there isn’t any reason why you couldn’t place EEK on your USB.
I tried/used Emsisoft Anti Malware some years back.
and liked the product.
Can’t remember if EEK was an option back then.
Well it would appear there is a very good reason not.
I created an EEK folder on my 8GB USB stick and ran the installation file and pointed it at the USB EEK folder. It took a very long time to extract and copy files to that folder.
Next running the 64bit executable to start, that too took some time and then suggested checking for updates, which I did and that took even longer, checking for updates and latest definitions, etc. etc. When the scan started (I had elected not to scan for PUPs and the shortest scan) it took quite some time calculating what would be scanned.
I went off and left it to run, despite having not to scan for pups, it reported what it considered a PUP entry in the registry (from the information shown, there really wasn’t any way to determine that) and I unchecked that. I got a few messages ‘had my AV let me down’ etc. etc. (which I closed).
All in all this isn’t an experience I would be prepared to do every time, too much hassle. For me it is dead in the water, certainly for a USB installation, I’m not even sure I would like to install it on a hard drive (certainly not on my primary SSD drive).
Hi Dave, strange that you had such issues. :-
I installed it on countless user systems (HDD/SSD/USB) over the years and it always did run smooth and fast.
I can confirm that the first program/signature update can take a while but subsequent updates should be much faster.
That isn’t your fault.
For me everything moved at snails pace my win10 laptop is pretty quick and it was connected via LAN network cable (not WiFi) on a relatively Hi-Speed fibre optic broadband connection.
Unfortunately any potential benefit (with the protection I already have) just wasn’t worth the hassle.
Guess, you won’t need it anyway, as Avast is doing a great job.
Nevertheless, I’ll keep using it as a “just in case - if needed” tool.
For portable second opinion scanner, TrendMicro HouseCall now functions this way instead of being web browser based.
I know this is an old thread, but I have a valid question.
I have had constant issues with Avast Rescue Disk and have lost all confidence in it.
Is EEK a valid substitute for Rescue Disk? as I have a good USB doing nothing right now since Rescue Disk again fails.
PS. I have used Trend Micro Housecall in the past when it was a online service, that worked, but not tried it lately.
Im just looking for a best freestanding backup AV that actually works reliably, in case all goes pear shaped.
It depends what you need. As EEK is portable you can use it on an USB.
But EEK doesn’t create bootable media, so you need to have one ready.
I suggest you take a look here,
https://www.makeuseof.com/tag/5-best-rescue-disks-windows-system-restore/