Here’s the deal.  AVG LinkScanner doesn’t execute javascript nor take cookies.  I had that confirmed by the Chief Research Officer at AVG, Roger Thompson. 

So why is the AVG user agent showing up in that data collected from certain page tag configurations?  The AVG LinkScanner currently requests gifs in noscript tags!

A best practice in web analytic’s page tag configuration is to use the noscript tag to serve the gif to non-javascript executing browsers.  Here’s some commonly seen (obscured) code for doing that:

<noscript>
<div><img alt=”foo” id=”bar” width=”1″ height=”1″ src=”http://
foo.bar.com/xyzab57yw10000s1s8g0boozt_9t1x/foo.gif?baruri=/
nojavascript&xy.js=No&xy.tv=1.2.3″ mce_src=”http://
foo.bar.com/xyzab57yw10000s1s8g0boozt_9t1x/foo.gif?baruri=/
nojavascript&xy.js=No&xy.tv=1.2.3″div>
</noscript>

<NOSCRIPT>
<IMG
src=”//foo.bar.com/xyz.gif?Log=1&URL=/javascript_disabled” mce_src=”//foo.bar.com/xyz.gif?Log=1&URL=/javascript_disabled”
BORDER=”0″ WIDTH=”1″ HEIGHT=”1″ />
</NOSCRIPT>

<noscript>
<img src=http://pt.foobar.com/images/xyz.gif?js=0” height=”1″
width=”1″
border=”0″ hspace=”0″ vspace=”0″ alt=”"> 

Thus, if you are using noscript tags in your page tag *and* someone with the AVG Linkscanner views a SERP (search engine results page)  from Google/Yahoo/MSN that lists your site, the traffic from the LinkScanner will be counted. 

Of course the simple solution to fix this problem is to exclude the user agent: 

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)

If don’t have full control over your page tag based web analytics implementation (i.e. hosted), you need to verify that your vendor has excluded this agent.   And you should have them audit your data going back to April, and refund/credit you any money.  Good luck with that though!

How big is the problem?  Well, it depends!

The amount of AVG traffic will vary dramatically by site.  Your site must show up in the SERP’s on computers of visitors that have AVG LinkScanner installed, and you must be using noscript tags to serve the gif.

I’ve made AVG aware of this issue.  And frankly, they’ve been a fantastic company to work with, so I’m sticking with them (for now ;).  First they allowed me to join a private Google group to discuss my findings, both the Head of Global Communications and Chief Research Officer quickly responded to all my emails (good social media response), and their engineers are looking into this issue so that they can fix it…  That’s pretty impressive and quick response.  So cheers to them!

It’s worth mentioning that the LinkScanner isn’t _supposed_ to request images, so I do think this issue will get fixed.

Only time will tell whether or not AVG obfuscates the user agent so it looks just like a “normal” browser.  Let’s hope not! 

What I do find interesting is that I’m already hearing that an agent exists with the string (Mozillia/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813). Note the “ia” mispelling of Mozilla as incorrectly documented here.  And it accepts cookies.  So AVG’s agent is already being spoofed.  Not good, not good.

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