Date: Tue, 20 Apr 2004 13:32:40 -0700 From: Dragos Ruiu <dr@kyx.net> To: Mike Tancsa <mike@sentex.net>, des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?= ) Cc: freebsd-security@freebsd.org Subject: Re: TCP RST attack Message-ID: <200404201332.40827.dr@kyx.net> In-Reply-To: <6.0.3.0.0.20040420144001.0723ab80@209.112.4.2> References: <6.0.3.0.0.20040420125557.06b10d48@209.112.4.2> <xzp65buh5fa.fsf@dwp.des.no> <6.0.3.0.0.20040420144001.0723ab80@209.112.4.2>
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On April 20, 2004 11:43 am, Mike Tancsa wrote: > At 02:26 PM 20/04/2004, Dag-Erling Sm=F8rgrav wrote: > >Dragos Ruiu <dr@kyx.net> writes: > > > On April 20, 2004 10:44 am, Dag-Erling Sm=F8rgrav wrote: > > > > The advisory grossly exaggerates the impact and severity of this > > > > fea^H^H^Hbug. The attack is only practical if you already know the > > > > details of the TCP connection you are trying to attack, or are in a > > > > position to sniff it. > > > > > > This is not true. The attack does not require sniffing. > > > >You need to know the source and destination IP and port. In most > >cases, this means sniffing. BGP is easier because the destination > >port is always 179 and the source and destination IPs are recorded in > >the whois database, but you still need to know the source port. > > While true, you do need the source port, how long will it take to > programmatically go through the possible source ports in an attack ? That > only adds 2^16-1024 to blast through Also keep in mind ports are predictable to varying degrees depending on the vendor or OS, which further reduces the brute force space you have to=20 go though without sniffing. That's what this thing boils down to imho - the space you have to blast through, the time you have to do it in, and=20 the bandwidth/rate available to do it. And there are competing factors, and questions about what are the real world values. I'm still waiting on final answers... cheers, =2D-dr =2D-=20 Top security experts. Cutting edge tools, techniques and information. Vancouver, Canada April 21-23 2004 http://cansecwest.com pgpkey http://dragos.com/ kyxpgp
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