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<br><div><div>On 20-Jul-07, at 7:54 AM, Dmitry Shechtman wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"> <div class="Section1"><p class="MsoNormal" style="margin-left:36.0pt"><font size="3" color="black" face="Times New Roman"><span style="font-size:12.0pt">The attack vector: I poison your local DNS resolver, or proxy all traffic, so that <a href="http://foo.blogspot.com">http://foo.blogspot.com</a> actually resolves to <a href="http://evil.org">http://evil.org</a>'s IP. If you follow the 302 redirect, you could be allowing evil.org to tell you what the "canonical" URL is. For example it could do a 302 redirect over to <a href="https://evil.org">https://evil.org</a> which presents a valid certificate and which can masquerade as the user's OP, capturing their password. (For users who check URLs, it could be <a href="https://my.open1d.org">https://my.open1d.org</a> instead of <a href="https://evil.org">https://evil.org</a>.)</span></font><font size="2" color="navy" face="Arial"><span style="font-size:10.0pt;font-family:Arial; color:navy"><o:p></o:p></span></font></p><p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10.0pt;font-family:Arial;color:navy"><o:p> </o:p></span></font></p><p class="MsoNormal"><font size="2" color="navy" face="Arial"><span style="font-size: 10.0pt;font-family:Arial;color:navy">Pardon my ignorance regarding TLS, but I don’t see what protection it would provide against such an attack. Is TLS similar to SSL with the exception of http prefix usage?</span></font></p></div> </blockquote></div><div>In most discussions (i.e. ones that don't concern themselves with which version of SSL you're using) TLS and SSL are used as synonyms. TLS (Transport Layer Security) is the name of an IETF standard based on SSL v3. </div><div><br class="webkit-block-placeholder"></div><div>As Dmitry observes, the protection it offers is useless if there are http (i.e. non-SSL/TLS) links in the chain. In an environment where the entire exchange happens over SSL/TLS though, the argument is that DNS spoofing/redirect attacks won't work, because an attacker cannot obtain a CA-signed certificate for a domain they don't own. Thus, even when the spoofed DNS has redirected trusted-id.com to evil-evil-hooray.com, attempts to verify the certificate of this false "trusted-id.com" will fail, and presumably the connection will be killed.</div><div><br class="webkit-block-placeholder"></div><div>Cheers,</div><div><br class="webkit-block-placeholder"></div><div>Johnathan</div><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>---</div><div>Johnathan Nightingale</div><div>Human Shield</div><div><a href="mailto:johnath@mozilla.com">johnath@mozilla.com</a></div><div><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span> </div><br></body></html>