Author Topic: how avast blocks threats  (Read 9864 times)

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Offline avast 15

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how avast blocks threats
« on: July 15, 2010, 02:09:48 AM »
whenever i surf the net i sometimes run into sites that are effected and avast alerts me with a pop up and blocks the website from appearing but sometimes it doesnt block the site it shows it. How is the threat blocked if the site sometimes is still showed when you click to go to it?

Offline DavidR

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Re: how avast blocks threats
« Reply #1 on: July 15, 2010, 02:19:15 AM »
avast only blocks the infected element, if the detection isn't on the actual web page then it is entirely possible that the page will display, but the infected element will have been blocked.

The web shield filters all http port 80 traffic and scans it in its local proxy, if it is infected avast aborts that connection and discards that item, so it doesn't end up in your browser cache to be either run or viewed on your browser.

In the majority of cases the infection is actually inserted into the main page (an HTML javascript script or iframe tag) if that is the case then the page won't display as the page code in its entirety is discarded.

Me if avast alerted on a site yet the page still loaded, I know it is an item in that site called or imported into that page, so there is no way I would continue using that site and avoid other such alerts.
Windows 10 Home 64bit/ Acer Aspire F15/ Intel Core i5 7200U 2.5GHz, 8GB DDR4 memory, 256GB SSD, 1TB HDD/ avast! free 21.3.2459 (build 21.3.6164.561) UI 1.0.609/ Firefox, uBlock Origin, uMatrix/ MailWasher Pro/ Avast! Mobile Security

Offline avast 15

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Re: how avast blocks threats
« Reply #2 on: July 15, 2010, 02:26:13 AM »
can you save an image or video of an effected site if the site still loads?

Offline Lisandro

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Re: how avast blocks threats
« Reply #3 on: July 15, 2010, 03:07:09 AM »
Can you post the links to these sites?
Post hxxp instead of http (not live links).
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Offline avast 15

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Re: how avast blocks threats
« Reply #4 on: July 15, 2010, 03:09:00 AM »
 im just wondering in general i dont have any links

Offline DavidR

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Re: how avast blocks threats
« Reply #5 on: July 15, 2010, 03:17:48 AM »
can you save an image or video of an effected site if the site still loads?

I wouldn't attempt to do anything on a site that avast has alerted on (I would exit the site even if it displayed) as you never know what else might be lurking around the next link. I would think it very unusual if a site has been hacked (the most common reason avast alerts, certainly for known sites) and there was only one instance of infection/exploit/redirect, etc. etc.

So you simply can't rely on avast absolutely catching everything, whilst I would say that avast's web shield protection is probably the best out there, nothing is 100%.
Windows 10 Home 64bit/ Acer Aspire F15/ Intel Core i5 7200U 2.5GHz, 8GB DDR4 memory, 256GB SSD, 1TB HDD/ avast! free 21.3.2459 (build 21.3.6164.561) UI 1.0.609/ Firefox, uBlock Origin, uMatrix/ MailWasher Pro/ Avast! Mobile Security

ravi16aug

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Re: how avast blocks threats
« Reply #6 on: July 15, 2010, 12:34:10 PM »
It also depends on the browser that is being used. I have seen the sites being completely blocked in IE and FF, but the same site loads completely in Chrome. avast! alerts on all 3 though.

Offline DavidR

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Re: how avast blocks threats
« Reply #7 on: July 15, 2010, 04:14:51 PM »
Yes the browser is also a factor, some don't obey the aborted connection but continue to try and complete the download.
Windows 10 Home 64bit/ Acer Aspire F15/ Intel Core i5 7200U 2.5GHz, 8GB DDR4 memory, 256GB SSD, 1TB HDD/ avast! free 21.3.2459 (build 21.3.6164.561) UI 1.0.609/ Firefox, uBlock Origin, uMatrix/ MailWasher Pro/ Avast! Mobile Security

Offline Pondus

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Re: how avast blocks threats
« Reply #8 on: July 15, 2010, 04:28:28 PM »
And Opera somtimes block before avast so you don`t see any avast warning......

ravi16aug

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Re: how avast blocks threats
« Reply #9 on: July 15, 2010, 05:45:53 PM »
There was a thread going on in MSE forums where one of the experts clearly explained that as of now, only Firefox and Internet Explorer make use of a Windows API that allows them to pass each item to the AV installed in the system before rendering it. It does not depend what AV it is. This is the reason why MSE's system requirements page explicitly mentions IE and FF and not Chrome, Opera or Safari. And that is also part of the justification behind MSE not having a dedicated web-shield.

Offline avast 15

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Re: how avast blocks threats
« Reply #10 on: July 17, 2010, 08:41:13 AM »
so if im using chrome or opera i wouldnt be as safe?

ravi16aug

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Re: how avast blocks threats
« Reply #11 on: July 17, 2010, 09:15:21 AM »
so if im using chrome or opera i wouldnt be as safe?
A conclusion can be reached only when some official response from the avast! team can clear this up. But since I have seen this thing in action, with both avast! (all shields on) and Symantec EndPoint Protection, I have been sticking with IE and FF only.
avast! did alert in case of Chrome, but it was after the page had fully rendered and manage to activate the Java Runtime Environment in my system. With IE and FF, the page was blocked completely.

Offline Pondus

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Re: how avast blocks threats
« Reply #12 on: July 17, 2010, 10:38:20 AM »
so if im using chrome or opera i wouldnt be as safe?
In my case Opera was blocking the website from loading before avast.......

Offline Tweakerz

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Re: how avast blocks threats
« Reply #13 on: July 17, 2010, 02:20:04 PM »
Hey guys, I know I am new here but I happened across this thread and I am a big fan of Opera and although this differs from the topic to some degree I felt due to the nature of the content it would not upset the staff that I post here to make sure the info gets to the right person(s) rather than in a new location that those here might miss. What I wished to share is not related to Avast blocking something but rather enhancing Opera a bit by adding Web of Trust, many may have already seen the bookmarklet method but less have seen the user javascript version which is by far preferred due to the fact it works much closer to the way it would with Firefox. Anyways, thought it might be useful to mention so I just wished to offer the link containing information someone might enjoy.

http://extendopera.org/userjs/content/wot-opera

Again, I hope I haven't upset staff due to the slight topic shift.

Offline DavidR

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Re: how avast blocks threats
« Reply #14 on: July 17, 2010, 05:57:45 PM »
WOT is not the oracle it purports to be, it is community based and relies on the quality of the user reporting sites, etc. I use WOT with Firefox and have come across many anomalies, sites that are flagged as bad that are good and worse still sites that are bad that are flagged as good.

So WOT should be used as a guide not total reliance.
Windows 10 Home 64bit/ Acer Aspire F15/ Intel Core i5 7200U 2.5GHz, 8GB DDR4 memory, 256GB SSD, 1TB HDD/ avast! free 21.3.2459 (build 21.3.6164.561) UI 1.0.609/ Firefox, uBlock Origin, uMatrix/ MailWasher Pro/ Avast! Mobile Security