<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><meta http-equiv="content-type" content="text/html; charset=utf-8"><div style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><br><div><blockquote type="cite"><meta http-equiv="content-type" content="text/html; charset=utf-8"><div style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div>On 3 Sep 2024, at 21:13, Jerry Leichter <leichter@lrw.com> wrote:<br><blockquote type="cite"></blockquote><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font>We've been discussing this recently, and ... the following just appeared:<br><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font>https://arstechnica.com/security/2024/09/yubikeys-are-vulnerable-to-cloning-attacks-thanks-to-newly-discovered-side-channel/<br><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font>Summary: Yubikeys, and a bunch of other devices that use a commonly available chipset and library, are vulnerable to an attack because of a non-constant-time implementation of the Euclidean algorithm. The attack relies on physical possession of the device and makes it possible to clone it or (sometimes?) extract the internal private key. They've demonstrated that possession for half an hour is enough. The detailed report - at https://ninjalab.io/wp-content/uploads/2024/09/20240903_eucleak.pdf - shows that their method of getting at the traces requires disassembling - hence effectively destroying - a Yubikey.<br><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font>A practical real-world attack? Not quite, but rather close.<br><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font> -- Jerry<br><font color="#00c8fa"><span style="caret-color: rgb(0, 200, 250);"><br></span></font>_______________________________________________<br>The cryptography mailing list<br>cryptography@metzdowd.com<br><div><div>https://www.metzdowd.com/mailman/listinfo/cryptography<br></div></div></div></div></blockquote><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>The problem is in the cloning. The EM-probe needs to be <i>very </i>close the silicon surface, the Yubi-key must be “opened” destructively.<br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>So, what security policy ameliorates this? <br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>1.1 If your Yubikey is lost (i.e. you don’t have it your possession anymore), you need to notify your security team without delay and that team will deregister the associated key in a timely fashion.<br>1.2. If your Yubikey is damaged in any way (visibly and/or “doesn’t seem to work”), you need to return the Yubi key without delay to your organisation’ s issuer, which decommissions it in a timely fashion.<br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>Well, these should already be in place, isn't it?<br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>Oh, and don’t forget the security policies when these policies are not met in a timely fashion etc etc ;-) <br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font>/Twan van der Schoot.<br><br><font color="#bf5af2"><span style="caret-color: rgb(191, 90, 242);"><br></span></font><span style="orphans: 2; widows: 2;">—</span><br><span style="orphans: 2; widows: 2;">Twan van der Schoot</span><br><span style="orphans: 2; widows: 2;">Bezembinder 86</span><br><span style="orphans: 2; widows: 2;">2401 HN Alphen aan den Rijn</span><br><span style="orphans: 2; widows: 2;">email : twanvds@xs4all.nl</span><br><span style="orphans: 2; widows: 2;">mobile: 06-15052501</span><br><span style="orphans: 2; widows: 2;">website: http://www.twan.com</span><br><blockquote type="cite"></blockquote><br></div><br></div></body></html>