Malevolent Download

[warburg]

I have a 15" 2017 MacBook Pro running OS 10.13.4: On a couple of occasions while using Safari, I have had a pop-up box appear that says my computer is blocked and that I need to call a certain telephone number to unblock it. I realize that this is some kind of scam, so I simply continue with what I am doing. However, whatever this program is, it dumps dozens, perhaps 100-200, files into my Downloads folder. These files bear the Safari logo and are labeled "unknown file." Has anyone else encountered this problem? Is there any way to prevent it from happening? Also, is there a way of emptying the Downloads folder of more than one file at a time?
Apparently no malware is involved. At least nothing is detected in a Malwarebytes scan.

 

[Schranke]

Run this at once
https://www.malwarebytes.com

 

[warburg]

Run this at once
https://www.malwarebytes.com

As I wrote, nothing is detected in a Malwarebytes. scan.

 

[Schranke]

As I wrote, nothing is detected in a Malwarebytes. scan.

missed that first time I read through...
Do you have a screenshot of the pop-up?
also what processes are active in activity monitor?

 

[NoBoMac]

Sounds like you are hitting a sketchy-ish site and or site's CDN provider has been compromised.

Install an ad blocker. Won't 100% stop this, but, will greatly reduce the amount of ads and scam ads.

 

[tram]

Install Blackfog Privacy.. They also have a new version for Mac coming out this week.

 

[Ulenspiegel]

warburg, do you use an adblocker with Safari?

 

[warburg]

warburg, do you use an adblocker with Safari?

No, I don't have an ad blocker. I had problems with these in the past.

I'll look into Blackfog Privacy

 

[Schranke]

No, I don't have an ad blocker. I had problems with these in the past.

I'll look into Blackfog Privacy

otherwise I would recommend 1Blocker (it is paid through the Mac App Store)

 

[Ulenspiegel]

No, I don't have an ad blocker. I had problems with these in the past.

I'll look into Blackfog Privacy

I hear you. Nevertheless, some of the adblockers are more and more sophisticated. Worth a try.
I wish you luck.

 

[warburg]

I called Apple Care. Although they didn't know the cause of my problem, they at least showed me how to empty the Downloads folder. I must have had 200-300 files in there, and I was taking them out of the folder one at a time because I was trying to drag and drop using two fingers on different hands. Apparently if you click and drag with fingers on the same hand, you can trash them all.

 

[hobowankenobi]

Besides downloads, you might look at:

Cache
Cookies
Extensions
Plug-ins

nagware can lurk in different browser places...

Another tool that might be useful: DetectX Swift

Just bumped into a few weeks ago, and it seems pretty good. Scans for adware, malware, and keyloggers, and has a nice Profile view that shows a complete log of what is installed, third party kexts, launch daemons, and what is configured (firewall, etc), all in one place. My only concern is that without current (very recent) definitions, its usefullness with steadily diminish. Hopefully the dev keeps it current, and has a good & current threat list.