A Bing Community thread reports from one webmaster that someone is masking MSNBot around as a browser, either Internet Explorer or Mozilla Firefox. Here are the reported IPs and UserAgent's being reporting by this webmaster:
The following IP addresses are from MSN's search bots, but use what appears to be just normal user agents.
65.55.109.22
65.55.109.106
65.55.109.118
65.55.109.119
65.55.109.120
65.55.109.162
65.55.109.209
65.55.109.212
65.55.110.16
65.55.110.21
65.55.110.41
65.55.110.88
65.55.110.107
65.55.110.121
65.55.110.132
65.55.110.164The user agent looks like this "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SLCC1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; InfoPath.2)"
This is not the first time Microsoft Bing has been accused of masking their bots as browser useragents. We had a similar report back in September where MSNBot was using Mozilla by way of UserAgent.
Brett Yount, Bing's representative, said, "Could you send this information to bwmc@microsoft.com and I will have the crawling team investigate?"
So currently, this is not confirmed, but it is weird.
Forum discussion at Bing Community.