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From Brett Hutley <br...@hutley.net>
Subject Re: mod_proxy and HTTP 302 response
Date Tue, 20 Aug 2002 12:27:29 GMT
Brett Hutley wrote:

> Yup. Note that the way 2.0.40 handles this, it strdups WHATEVER is 
> pushed through afterwards to the status_line member of the request_rec 
> structure. This seems to me to be potentially dangerous... as in; push 
> exploit machine code onto the heap through this function, and then 
> take advantage of a smaller buffer overflow opportunity elsewhere to 
> indirect through to your HUGE_STRING_LEN-13 sized exploit function... 
> of course this depends on there actually BEING another buffer overflow 
> opportunity elsewhere.... and being able to access the pointer to the 
> request_rec structure, and then DNS-cache-poisoning the internal dns 
> server so the web server proxies from the evil machine that serves the 
> bad headers rather than the server you THINK you are proxying from... 
> so it's very, very, unlikely to be exploited. The fix is so trivial 
> though (make sure the HTTP response string length is greater than 13 
> bytes).

Hmmm, just realised that an attacker can send through the exploit code 
in the reason string anyway. I guess the patch will only help with 
broken servers sending through broken status lines in the response 
message (which, funnily enough,  was it's original purpose). Please 
consider the above a momentary attack of  insanity, while I give myself 
a good whack with the clue stick.

Cheers, Brett



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