Is the description of the attack publicly available? On Wed, Sep 9, 2020 at 3:39 PM OpenSSL <open...@openssl.org> wrote:
> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > OpenSSL Security Advisory [09 September 2020] > ============================================= > > Raccoon Attack (CVE-2020-1968) > ============================== > > Severity: Low > > The Raccoon attack exploits a flaw in the TLS specification which can lead > to > an attacker being able to compute the pre-master secret in connections > which > have used a Diffie-Hellman (DH) based ciphersuite. In such a case this > would > result in the attacker being able to eavesdrop on all encrypted > communications > sent over that TLS connection. The attack can only be exploited if an > implementation re-uses a DH secret across multiple TLS connections. Note > that > this issue only impacts DH ciphersuites and not ECDH ciphersuites. > > OpenSSL 1.1.1 is not vulnerable to this issue: it never reuses a DH secret > and > does not implement any "static" DH ciphersuites. > > OpenSSL 1.0.2f and above will only reuse a DH secret if a "static" DH > ciphersuite is used. These static "DH" ciphersuites are ones that start > with the > text "DH-" (for example "DH-RSA-AES256-SHA"). The standard IANA names for > these > ciphersuites all start with "TLS_DH_" but excludes those that start with > "TLS_DH_anon_". > > OpenSSL 1.0.2e and below would reuse the DH secret across multiple TLS > connections in server processes unless the SSL_OP_SINGLE_DH_USE option was > explicitly configured. Therefore all ciphersuites that use DH in servers > (including ephemeral DH) are vulnerable in these versions. In OpenSSL > 1.0.2f > SSL_OP_SINGLE_DH_USE was made the default and it could not be turned off > as a > response to CVE-2016-0701. > > Since the vulnerability lies in the TLS specification, fixing the affected > ciphersuites is not viable. For this reason 1.0.2w moves the affected > ciphersuites into the "weak-ssl-ciphers" list. Support for the > "weak-ssl-ciphers" is not compiled in by default. This is unlikely to cause > interoperability problems in most cases since use of these ciphersuites is > rare. > Support for the "weak-ssl-ciphers" can be added back by configuring > OpenSSL at > compile time with the "enable-weak-ssl-ciphers" option. This is not > recommended. > > OpenSSL 1.0.2 is out of support and no longer receiving public updates. > > Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2w. If > upgrading is not viable then users of OpenSSL 1.0.2v or below should ensure > that affected ciphersuites are disabled through runtime configuration. Also > note that the affected ciphersuites are only available on the server side > if a > DH certificate has been configured. These certificates are very rarely > used and > for this reason this issue has been classified as LOW severity. > > This issue was found by Robert Merget, Marcus Brinkmann, Nimrod Aviram and > Juraj > Somorovsky and reported to OpenSSL on 28th May 2020 under embargo in order > to > allow co-ordinated disclosure with other implementations. > > Note > ==== > > OpenSSL 1.0.2 is out of support and no longer receiving public updates. > Extended > support is available for premium support customers: > https://www.openssl.org/support/contracts.html > > OpenSSL 1.1.0 is out of support and no longer receiving updates of any > kind. > The impact of this issue on OpenSSL 1.1.0 has not been analysed. > > Users of these versions should upgrade to OpenSSL 1.1.1. > > References > ========== > > URL for this Security Advisory: > https://www.openssl.org/news/secadv/20200909.txt > > Note: the online version of the advisory may be updated with additional > details > over time. > > For details of OpenSSL severity classifications please see: > https://www.openssl.org/policies/secpolicy.html > -----BEGIN PGP SIGNATURE----- > > iQIzBAEBCgAdFiEEeVOsH7w9yLOykjk+1enkP3357owFAl9YzBsACgkQ1enkP335 > 7oyIxg/9FWuca3/s/lY6g6a5VTPIekZMOLRUnDyzS3YePQu/sEd1w81mKoTqU+6F > KQmliGqdRDk+KN8HDVd14kcLBukto8UKmkp9FpB5J4d2KK1I/Fg/DofJs6xUQYKb > 5rHRLB3DDoyHEBzEEIjcqYTTThXW9ZSByVK9SKpC78IRM/B2dfd0+j4hIB/kDC/E > G+wieFzexHQVdleVYT/VaJ6qS8AwvohBbt8h7yK0P6v/4vEm0spDbUmjWJBVUlUu > QZyELjj8XZR3YFxt3axSuJg3JSGYlaMzkt2+DVq4qEzeJLIydLK9J8p6RNwPhsJk > Rx0ez8P4N+5O7XmA0nHv3HyompdMgHlvykj8Ks4lNHVS02KKLi1jDtmOxl3Fm/hb > ZNOmjn7lulV1342pw4rWL3Nge3x0s0Q5zgBCm1mqLzzu/V1ksx8FJwGA1w2cH280 > dU9VedkC2wvFQije8pFrWH9l6N9Bh41DIEOnlBl0AL7IrbPdO6yMcD6vpR7hWjr3 > fx4hNJSAGzJ3i/NXlSj4eR/47zkjfJyEc8Drc2QgewyqXFrK20X/LOj8MqJlc+ry > pXZseh+XC8WaYDMV1ltrKvE2Ld9/0f3Ydc04AcDeu5SXPJG79ogzVnchZok7+XCj > RT+a3/ES45+CTfL5v27t5QJxJcxg4siLVsILfi0rIUv0IYgH2fU= > =U7OO > -----END PGP SIGNATURE----- > -- SY, Dmitry Belyavsky