Full Disclosure mailing list archives
Re: [VulnDiscuss] Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble
From: Florian Weimer <Weimer () CERT Uni-Stuttgart DE>
Date: Fri, 23 Apr 2004 15:14:53 +0200
Kurt Seifried wrote:
Please note: According to the Cisco presentation afterwards, Cisco's RST behavior makes it non vulnerable as there is a wait period after a certain number of bad RST packets are recieved. Thus Cisco IOS is basically not affected.
This is not quite true according to the advisiories. You flood the other side with SYN segments (which are NOT rate limited). Only if the segment number is acceptable, the other side generates an RST segment which tears down the connection. RST rate limits do NOT help here. Even if you drop RST segments completely, the other side probably makes a state transition away from ESTABLISHED so that connection is eventually broken (I haven't tested this, but it's required according to RFC 793). The SYN issue is not present in the Watson's paper, by the way. I don't know how he was able to attack those TCP connections with RST segments. Probably he didn't test an IOS-to-IOS TCP connection. -- Florian Weimer Weimer () CERT Uni-Stuttgart DE University of Stuttgart ZENDAS fax +49-711-121-3688 _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- TCP Reset Attacks: Paper and Code Now Availble sullo (Apr 22)
- Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble Kurt Seifried (Apr 23)
- Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble sullo (Apr 23)
- Re: [VulnDiscuss] Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble Florian Weimer (Apr 23)
- Re: [VulnDiscuss] Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble Kurt Seifried (Apr 23)
- Re: Re: [VulnDiscuss] Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble Gregory A. Gilliss (Apr 23)
- Re: [VulnWatch] TCP Reset Attacks: Paper and Code Now Availble Kurt Seifried (Apr 23)