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Re: IE 5.x keep-alive session hijacking

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 

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 

DM> Best regards,
DM> Domas Mituzas
DM> MicroLink Data 

Впрочем, важнее всего - алгоритм!  (Лем)