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OpenSSL / LibreSSL CVE-2016-7056
From: |
Leo Famulari |
Subject: |
OpenSSL / LibreSSL CVE-2016-7056 |
Date: |
Tue, 10 Jan 2017 13:16:52 -0500 |
User-agent: |
Mutt/1.7.2 (2016-11-26) |
CVE-2016-7056 has been published:
http://seclists.org/oss-sec/2017/q1/52
Quoted from that email:
Attack Vector: Local
Vendor: OpenSSL, LibreSSL, BoringSSL
Versions Affected:
OpenSSL 1.0.1u and previous versions
LibreSSL (pre 6.0 errata 16, pre 5.9 errata 33)
BoringSSL pre November 2015
Description:
The signing function in crypto/ecdsa/ecdsa_ossl.c in certain OpenSSL versions
and forks
is vulnerable to timing attacks when signing with the standardized elliptic
curve P-256 despite featuring constant-time curve operations and modular
inversion.
A software defect omits setting the BN_FLG_CONSTTIME flag for nonces, failing
to take a secure code path in the BN_mod_inverse method and therefore resulting
in a cache-timing attack vulnerability.
A malicious user with local access can recover ECDSA P-256 private keys.
Mitigation:
Users of OpenSSL with the affected versions should apply
the patch available in the manuscript at [1].
Users of LibreSSL should apply the official patch from OpenBSD [2,3].
Users of BoringSSL should upgrade to a more recent version.
Credit:
This issue was reported by Cesar Pereida GarcĂa and Billy Brumley
(Tampere University of Technology).
Timeline:
19 Dec 2016 Disclosure to OpenSSL, LibreSSL, BoringSSL security teams
29 Dec 2016 Embargo lifted
References:
[1] http://ia.cr/2016/1195
[2]
https://ftp.openbsd.org/pub/OpenBSD/patches/5.9/common/033_libcrypto.patch.sig
[3]
https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/016_libcrypto.patch.sig
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