A highly technical look at the new TCP flaw

Shalmanese

Platinum Member
Sep 29, 2000
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The media has been going on about it here, here and here but it is all fairly simplistic and looks to be from the same primary source. I was wondering if anybody is qualified to look at this from a technical perspective or has a link to a site that does.

For what I can gather, it has something to do with spoofing the right packet to end a session and to do that, you need to guess the randomly generated 32 bit session ID. There is some flaw in the algorithm used to generate session ID's which means that the search space is much, much smaller so attackers can use brute force to guess the packet.

Thats what I can get out of the press but my knowledge of TCP is a bit rusty so I would appreciate someone else have a look at the issue.
 

CTho9305

Elite Member
Jul 26, 2000
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No, TCP packets are sent with sequential numbers. The flaw is that TCP receive windows can be very large, and a RST packet anywehre in the current range of accepted packets can reset the connection.