IE 5.x keep-alive session hijacking

["Domas Mituzas" <Domas.Mituzas@xxxxxxxxxxxx>]

Hi,

sorry for being innacurate, but I noticed that our transparent-proxy system is 
trying (and even to succeeds at some level) to hijack client http connections. 
I asked users to supply us with their browser versions, and all of resulted 
answers were MS Internet Explorer. I didn't have too much time to investigate 
this issue, but here's how I imagine the problem. The transparent reverse proxy 
provides with Proxy-Connection: header, that can be misinterpretated by MSIE, 
so the browser software directs all further requests via proxy solution. It is 
possible to answer positively to any request, so browser continues to use proxy 
server transparently. Though, we've got ACLs forbidding such usage of our proxy 
servers, one can use such MITM attack to get cookies, input data, etc. Possibly 
that can be caused sometimes on other browser configurations as well. 

Best regards,
Domas Mituzas
MicroLink Data