Dear Domas Mituzas, I can't confirm this behaviour for IE 5.5 and 6.0. May be behaviour your observe is a result of customer having his own proxy server (for example something like proxymitron, or some kind of ad killer, etc) before your transparent proxy and customer's proxy server doesn't strip Proxy-connection header before resending reply to IE, so IE thinks this header comes from proxy. This should be treated as proxy server vulnerability. 3proxy doesn't have one :) --Tuesday, September 2, 2003, 1:17:41 PM, you wrote to bugtraq@securityfocus.com: DM> Hi, DM> 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 DM> 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 DM> 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 DM> 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. DM> Possibly that can be caused sometimes on other browser configurations as well. DM> Best regards, DM> Domas Mituzas DM> MicroLink Data -- ~/ZARAZA Впрочем, важнее всего - алгоритм! (Лем)
