Our website is blocked by Avast for some of our customers

Avast Free Antivirus / Premium Security
1

Hello,

Some of our customers have problems accessing our website www.artprice.com :
the site is blocked by Avast. Disabling Avast for 10 minutes make the site available again.
It apears that our IP is blocked in the Avast firewall log (Port scan detection) ; when it accurs, all pings to our IP Fail.

Why Avast is detecting port scan from a web server ?
And what do we have to do to solve the broblem ?

Thanks.

2

Try turn off port scan, it seems there is a bug in it

Avast UI → Protection → Firewall → Settings → Advanced → Uncheck “Enable automatic port scan detection”

3

Although not blacklisted, there are some things that need to be taken care of.

Vulnerable libraries used:
http://retire.insecurity.today/#!/scan/ca1706b634d749ade983e0b75efa9642429f49947e86b4c0d9ae533122bc85fc

Multiple issues with the SSL/TLS certificate :
https://www.ssllabs.com/ssltest/analyze.html?d=www.artprice.com

4

Thanks for your replies !

@Pondus : This means that we should suggest this solution to all of our involved customers, right?

@Eddy : We have just dealt with our ssl/tls certificates ; thank you for the js-libraries scanning tool, we take care of it right away…

5
@Pondus : This means that we should suggest this solution to all of our involved customers, right?
Yes, see if that work ... i think avast is working on a port scan fix
6

You’re welcome.

In case you are interested, I have several links to tools, on-line scanners and such on my website. http://www.ache.nl

7

Hello,

some news about our case :

The problem is still here : our customers have to disable port scan detection to access our website.

We hope that Avast will correct the problem on their side, as other websites/DNS seem to be affected.

8

I have also had a problem with the Avast Firewall blocking access to internal Routers, WiFi APs and servers that use a browser on port 80 to log in.
Turning off Network shield does not fix the problem
Turning off Firewall does fix the problem.
Have added all the devices as ‘Friends’ to no avail.
Added an Intranet entry to Packet Rules to allow anything in/out for ‘Friends’ addresses to no avail.

Have now turned off the Automatic Port Scan and these does appear to sort the problem.

---------------------------UPDATE------------------------****

Following the recent update to version 17.4.2294 (build 17.4.3482.0) the problem is back.
I can momentarily log into a device on my internal network then within a minute it becomes unavailable along with every other internal web address. I can still browse and log into external websites but nothing internally.
I disable Avast IS and everything works.
Yes Automatic Port Scan Detection is disabled.
Yes Friends network is defined for the whole network range.

Also Opera is very slow to start.

And why I am on the subject does Avast insist on changing the internal network from Private to Public and back to Private when ever I login into my desktop PC with a static IP address on a hard wired ethernet connection ???
Yes Automatic network profile switching is disabled.

9

Je ne peux plus accéder à Artprice, qui est un site sûr pour lequel je paye un abonnement. Il est INDISPENSABLE pour mon activité que j’y ai accès. Pourquoi Avast bloque-t-il ce genre de site ???

10

Please post English here, else use the forum section for your language.
→ https://forum.avast.com/index.php?board=21.0

11

I can’t connect on www.artprice.com, which is secure and for which I pay an (expensive) charge once a year. It is absolutely necessary for me to reach this website. Presently, the connexion - when it works - last one or two minutes and that’s all.

12

See Reply #1 from Pondus.

13

OK, thanks, but I would prefer Avast make a correction…

14

Should be out soon…