<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Lets just tell folk SSL v3 is dead.<div><br></div><div>I can’t remember when TLS support became ubiquitous but it was old by the time SHA2 was specified.</div><div><br></div><div><br></div><div><br></div><div><div><div><br></div><div><br><div><div>On Oct 14, 2014, at 7:28 PM, Ben Wilson <<a href="mailto:ben.wilson@digicert.com">ben.wilson@digicert.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div lang="EN-US" link="blue" vlink="purple" style="font-family: Helvetica; font-size: 18px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Since I hinted at it earlier today, FWIW here is the news -<span class="Apple-converted-space"> </span><a href="https://www.openssl.org/~bodo/ssl-poodle.pdf" style="color: purple; text-decoration: underline;">https://www.openssl.org/~bodo/ssl-poodle.pdf</a><span class="Apple-converted-space"> </span> <o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">Poodle stands for “Padding Oracle On Downgraded Legacy Encryption”. CVE-2014-3566 has been reserved for this protocol vulnerability (no additional information is available yet at<span class="Apple-converted-space"> </span><a href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3566" style="color: purple; text-decoration: underline;">http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3566</a>).<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">The attack works by interfering with the establishment of a TLS connection. A client will quickly downgrade to SSLv3, which uses either the RC4 stream cipher (subject to information leakage) or a block cipher in CBC mode (subject to information leakage via the Poodle attack). <o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">As I understand the explanation, the man-in-the-middle decrypts the block ciphers by first padding a block with known values and then chipping away until the secure cookie (or other authentication data) is fully decrypted.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">If disabling SSLv3 is not feasible due to legacy system issues, the paper suggests a few mitigations, such as using TLS_FALLBACK_SCSV to prevent a downgrade in the first place.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;">“This use of TLS_FALLBACK_SCSV will ensure that SSL 3.0 is used only when a legacy implementation is involved: attackers can no longer force a protocol downgrade. (Attacks remain possible if both parties allow SSL 3.0 but one of them is not updated to support TLS_FALLBACK_SCSV, provided that the client implements a downgrade dance down to SSL 3.0.) “<o:p></o:p></div></div>_______________________________________________<br>Public mailing list<br><a href="mailto:Public@cabforum.org" style="color: purple; text-decoration: underline;">Public@cabforum.org</a><br><a href="https://cabforum.org/mailman/listinfo/public" style="color: purple; text-decoration: underline;">https://cabforum.org/mailman/listinfo/public</a></div></blockquote></div><br></div></div></div></body></html>