Hello
Does CIS automatically scan external hard drives when we connect them to the computer???
If yes can we disable this feature???
Yes, CIS scans everything on-access. You can add the drive letter to the exclusions: Antivirus → Scanner Settings → Exclusions → Add → Browse… and add the drive. I guess you may want to add the drive before connecting the external HDD - if so, just add C: (or any partition) and edit C: by changing C to the letter you know that the external HDD will have.
But, doesn’t this exclusion affect real time scan?
Yes, I thought that was what you asked for? CIS does not scan the whole HDD when you connect it - just the folders and files you browse/access - maybe that was your question? I hope I was clear now. :-[
I’m asking this because last week CIS detected a Trojan when I connected the external drive, inside the external hard drive
Removable devices can have autorunning code (autorun.inf or similar). This is automatically invoked when the removable device is plugged in. This autorunning code can invoke other apps, either on the removable drive or on your fixed hard drives.
In answer to your original questions;
Does CIS automatically scan external hard drives when we connect them to the computer???Yes, if the removable device autoruns or automatically activates an executable when first connected.
If yes can we disable this feature???Not easily.
You could add the drive letter as an exclusion to the real time scanner.
You could edit the registry to disable autoplay (not guaranteed to work in all cases).
You could press and hold the right SHIFT key when plugging in the removable device (not guaranteed to work in all cases).
I really can’t recommend disabling this check, however. Given that the drive is removable, it can be used on systems other than your and these may or may not have adequate AV to prevent it being infected while in these foreign systems.
Cheers,
Ewen 
I too wondered if there was a simpler way too choose which drives to scan when choosing manual scan, such as a display of drives connected with check boxes beside them to identify which drives to manually scan, instead of selecting manual scan, and having all drives scanned automatically.
On a similar note, one of my external drives seems to cycle intermittently, as if I am accessing a folder on the drive after it has been idle for a while, even when I am not. I wonder if this is due to real time scanning. I have noticed this even before using CIS, but I have always used a product with real time scanning since having my externals connected, so I am not sure if this is due to real time scanners or if it is the drive itself.
You can chose Antivirus | Scan Profiles | Add… | Add… and from there create your own profile by adding drives of your choice.
I may have noticed something similar, but I haven’t yet discovered what may cause it… so I can’t help you further there, right now. It seems to happen after defragmenting though, so I’m not positive it’s real time scanning related for me.
I contacted the manufacturer of the drive and explained the event, he suggested I unplug from power strip and directly plug into the wall outlet. This did not resolve the issue. He then stated if I wanted any more ideas to pull out the credit card. I have seen friends external HD’s made by the same manufacturer, look identical, however were different models, that do not display this behavior. Weird. Maybe one day we will figure this out.
I guess the mystery remains then. Thx for the info anyway.
Maybe it is because of Windows Indexing Service. When accessing the drive to index what is inside…
It access the file and CIS catch it…