IE 5.x keep-alive session hijacking

["Domas Mituzas" <Domas.Mituzas () microlink lt>]

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