OpenSSL Security Advisory

[Dmitry Belyavsky]

Could you please let me know when it is available?

On Wed, Sep 9, 2020 at 3:51 PM Mark J Cox <mark at openssl.org> wrote:

> They should be releasing their paper very soon (today).
>
> Regards, Mark
>
> On Wed, Sep 9, 2020 at 1:45 PM Dmitry Belyavsky <beldmit at gmail.com> wrote:
> >
> > Is the description of the attack publicly available?
> >
> > On Wed, Sep 9, 2020 at 3:39 PM OpenSSL <openssl at 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
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> >> -----END PGP SIGNATURE-----
> >
> >
> >
> > --
> > SY, Dmitry Belyavsky
>


-- 
SY, Dmitry Belyavsky
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