Date: Wed, 8 Jun 2016 17:33:35 +0200 From: Gsunde Orangen <gsunde.orangen@...il.com> To: oss-security@...ts.openwall.com Subject: Re: CVE-2016-2178: OpenSSL DSA follows a non-constant time codepath for certain operations ... which would be a different rating to the "moderate" that the RedHat team ended up with: https://access.redhat.com/security/cve/CVE-2016-2178 I agree that both ratings are reasonable; so still awaiting for the OpenSSL announcement at least in the vulnerability section ( https://www.openssl.org/news/vulnerabilities.html#y2016). (Could be that I am just too impatient ;-) 2016-06-08 17:18 GMT+02:00 Alex Gaynor <alex.gaynor@...il.com>: > I assume the OpenSSL team considers this vulnerability to be LOW severity: > https://www.openssl.org/policies/secpolicy.html > > Alex > > On Wed, Jun 8, 2016 at 11:15 AM, Gsunde Orangen <gsunde.orangen@...il.com> > wrote: > > > Whilst there is a commit in openssl and a CVE ID, I wonder why this > hasn't > > been announced yet by OpenSSL.org and why there are no official fix > > releases (yet). > > What made this issue different to the usual coordinated disclosures being > > practiced with the OpenSSL team? > > > > 2016-06-08 10:54 GMT+02:00 Solar Designer <solar@...nwall.com>: > > > > > Hi, > > > > > > Just off Twitter: > > > > > > <mjos_crypto> Out today: This is the OpenSSL side-channel > vulnerability I > > > mentioned last week; now on ePrint. Also CVE-2016-2178. > > > http://eprint.iacr.org/2016/594 > > > <@mjos_crypto> @mjos_crypto Currently unfixed in essentially all > distros. > > > <mjos_crypto> Note that CVE-2016-2178 / > > > http://eprint.iacr.org/2016/594.pdf most severely actually impacts > > > OpenSSH, which uses the OpenSSL library. > > > <mjos_crypto> Cesar's CVE-2016-2178 patch for the OpenSSL library from > > > Monday. > > > > > > https://git.openssl.org/?p=openssl.git;a=commit;h=399944622df7bd81af62e67ea967c470534090e2 > > > > > > http://eprint.iacr.org/2016/594 > > > > > > | "Make Sure DSA Signing Exponentiations Really are Constant-Time'' > > > | > > > | Cesar Pereida Garca and Billy Bob Brumley and Yuval Yarom > > > | > > > | Abstract: TLS and SSH are two of the most commonly used protocols for > > > securing Internet traffic. Many of the implementations of these > protocols > > > rely on the cryptographic primitives provided in the OpenSSL library. > In > > > this work we disclose a vulnerability in OpenSSL, affecting all > versions > > > and forks (e.g. LibreSSL and BoringSSL) since roughly October 2005, > which > > > renders the implementation of the DSA signature scheme vulnerable to > > > cache-based side-channel attacks. Exploiting the software defect, we > > > demonstrate the first published cache-based key-recovery attack on > these > > > protocols: 260 SSH-2 handshakes to extract a 1024/160-bit DSA host key > > from > > > an OpenSSH server, and 580 TLS 1.2 handshakes to extract a 2048/256-bit > > DSA > > > key from an stunnel server. > > > | > > > | Category / Keywords: applied cryptography; digital signatures; > > > side-channel analysis; timing attacks; cache-timing attacks; DSA; > > OpenSSL; > > > CVE-2016-2178 > > > | > > > | Date: received 6 Jun 2016, last revised 7 Jun 2016 > > > > > > > > > > > > https://git.openssl.org/?p=openssl.git;a=commit;h=399944622df7bd81af62e67ea967c470534090e2 > > > > > > | author Cesar Pereida > > > | Mon, 23 May 2016 12:45:25 +0300 (12:45 +0300) > > > | committer Matt Caswell > > > | Mon, 6 Jun 2016 13:08:15 +0300 (11:08 +0100) > > > > > > | Fix DSA, preserve BN_FLG_CONSTTIME > > > | > > > | Operations in the DSA signing algorithm should run in constant time > in > > > | order to avoid side channel attacks. A flaw in the OpenSSL DSA > > > | implementation means that a non-constant time codepath is followed > for > > > | certain operations. This has been demonstrated through a cache-timing > > > | attack to be sufficient for an attacker to recover the private DSA > key. > > > | > > > | CVE-2016-2178 > > > > > > Alexander > > > > > > > > > -- > "I disapprove of what you say, but I will defend to the death your right to > say it." -- Evelyn Beatrice Hall (summarizing Voltaire) > "The people's good is the highest law." -- Cicero > GPG Key fingerprint: D1B3 ADC0 E023 8CA6 >
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