AVG LinkScanner Obfuscates User Agent!
AVG has obfuscated their user agent. One of the current agents for customers of their free and paid tool now cloaks itself as IE6:
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
In addition to the easily detectable user agents:
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)User Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)User Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
This news is not good. If you filter SV1 agent, you risk filtering legitimate traffic from the IE6 browser. A few folks have commented to me that one should filter the user agent anyway, because 1) IE6 is in decline and 2) most IE6 users have .NET installed, which will show in the user agent. Still filtering it makes me a little uneasy.
Is this the death toll for log file analysis and services provided by ABCe (since they can’t filter this user agent either)? Maybe it is. AVG is touting that agent lacks HTTP Accept-Encoding, which is just dandy, but that information isn’t normally captured in logs.
So the current situation is this:
- AVG has two user agents. Both are filterable, but the SV1 agent is problematic to filter because you risk filtering legitimate traffic.
- Both agents in the current version request gifs in noscript tags, inflating counts in page tag implementations with noscript configurations. AVG claims they will fix this issue.
- The bot uses”mad” bandwidth. I’ve heard stories of bandwidth increasing 100x normal levels. Some webmasters are serving dummy files to the recognizable user agents, some aren’t serving content to IE 6 browsers (crazy), and some are redirecting the bot back to AVG (thus inflating AVG’s bandwidth, LOL!).
- Evidence points to this bot NOT inflating clicks from paid search (i.e. PPC) and thus NOT committing click fraud. But it doesn’t remain out of the realm of possibility that the scanner may be accessing an ad vendor click redirector and causing a click. Not trying to spread FUD here, just making a point.
- AVG is looking at option of checking either an external db (hosted by AVG) or a local cache to verify sites in SERP’s have been “scanned by AVG,” instead of repeatedly scanning sites every time they are listed in SERP, to reduce the bandwidth issue and minimize fraudulent entries in log files.
- AVG is thinking about enabling white listing of sites, so they are skipped by the scanner.
- AVG is thinking about exposing a meta-tag that instructs the scanner to ignore the site.
Good luck with this nasty bot! Interestingly, here’s how you smurf a site with the AVG LinkScanner.
