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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.1766 Side-channel attack fixed in libgcrypt 14 June 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: libgcrypt Publisher: GnuPG Operating System: Windows UNIX variants (UNIX, Linux, OSX) Impact/Access: Access Privileged Data -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2018-0495 Original Bulletin: https://lists.gnupg.org/pipermail/gnupg-announce/2018q2/000426.html - --------------------------BEGIN INCLUDED TEXT-------------------- Hi! The GnuPG Project is pleased to announce the availability of Libgcrypt versions 1.8.3 and 1.7.10. These releases mitigate a novel side-channel attack on ECDSA signatures and also bring fixes for a few other bugs. Libgcrypt is a general purpose library of cryptographic building blocks. It is originally based on code used by GnuPG. It does not provide any implementation of OpenPGP or other protocols. Thorough understanding of applied cryptography is required to use Libgcrypt. Noteworthy changes in version 1.8.3 =================================== - Use blinding for ECDSA signing to mitigate a novel side-channel attack. [#4011,CVE-2018-0495] - Fix incorrect counter overflow handling for GCM when using an IV size other than 96 bit. [#3764] - Fix incorrect output of AES-keywrap mode for in-place encryption on some platforms. - Fix the gcry_mpi_ec_curve_point point validation function. - Fix rare assertion failure in gcry_prime_check. Release info at <https://dev.gnupg.org/T4016>. We also released a new version of the older 1.7 branch with similar fixes. Comments on the attack ====================== Details on CVE-2018-0495 can be found in the paper "Return of the Hidden Number Problem" which can be downloaded from the advisory page <https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/>. See <https://dev.gnupg.org/T4011> for a timeline. One user of Libgcrypt is GnuPG, thus a quick comment: GnuPG does not use the vulenrable ECDSA signatures by default. Further, it is much harder to mount such an attack against an offline protocol like OpenPGP than against online protocols like TLS. Anyway, we also released a new Windows installer for GnuPG 2.2.8 featuring the fixed Libgcrypt version. That installer is linked from the usual download page and a new Gpg4win version will be released soon. Download ======== Source code is hosted at the GnuPG FTP server and its mirrors as listed at <https://gnupg.org/download/mirrors.html>. On the primary server the source tarball and its digital signature are: https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.8.3.tar.bz2 https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.8.3.tar.bz2.sig or gzip compressed: https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.8.3.tar.gz https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.8.3.tar.gz.sig The URLs for the older 1.7 branch are: https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.10.tar.bz2 https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.10.tar.bz2.sig https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.10.tar.gz https://gnupg.org/ftp/gcrypt/libgcrypt/libgcrypt-1.7.10.tar.gz.sig In order to check that the version of Libgcrypt you downloaded is an original and unmodified file please follow the instructions found at <https://gnupg.org/download/integrity_check.html>. In short, you may use one of the following methods: - Check the supplied OpenPGP signature. For example to check the signature of the file libgcrypt-1.8.3.tar.bz2 you would use this command: gpg --verify libgcrypt-1.8.3.tar.bz2.sig libgcrypt-1.8.3.tar.bz2 This checks whether the signature file matches the source file. You should see a message indicating that the signature is good and made by one or more of the release signing keys. Make sure that this is a valid key, either by matching the shown fingerprint against a trustworthy list of valid release signing keys or by checking that the key has been signed by trustworthy other keys. See the end of this mail for information on the signing keys. - If you are not able to use an existing version of GnuPG, you have to verify the SHA-1 checksum. On Unix systems the command to do this is either "sha1sum" or "shasum". Assuming you downloaded the file libgcrypt-1.8.3.tar.bz2, you run the command like this: sha1sum libgcrypt-1.8.3.tar.bz2 and check that the output matches the first line from the this list: 13bd2ce69e59ab538e959911dfae80ea309636e3 libgcrypt-1.8.3.tar.bz2 3b4d23db99ef13e6e305f536f009d9de8f5d0535 libgcrypt-1.8.3.tar.gz 66902603f7b6ad62c72db868d93b1772ac2a1afa libgcrypt-1.7.10.tar.bz2 a0aaea0c514c62de8533a955631134bc57f2e552 libgcrypt-1.7.10.tar.gz You should also verify that the checksums above are authentic by matching them with copies of this announcement. Those copies can be found at other mailing lists, web sites, and search engines. Copying ======= Libgcrypt is distributed under the terms of the GNU Lesser General Public License (LGPLv2.1+). The helper programs as well as the documentation are distributed under the terms of the GNU General Public License (GPLv2+). The file LICENSES has notices about contributions that require that these additional notices are distributed. Support ======= For help on developing with Libgcrypt you should read the included manual and optional ask on the gcrypt-devel mailing list [1]. A listing with commercial support offers for Libgcrypt and related software is available at the GnuPG web site [2]. If you are a developer and you may need a certain feature for your project, please do not hesitate to bring it to the gcrypt-devel mailing list for discussion. Thanks ====== Maintenance and development of GnuPG is mostly financed by donations. The GnuPG project currently employs one full-time developer and two contractors. They all work exclusively on GnuPG and closely related software like Libgcrypt, GPGME, and GPA. We have to thank all the people who helped the GnuPG project, be it testing, coding, translating, suggesting, auditing, administering the servers, spreading the word, and answering questions on the mailing lists. Special thanks to Keegan Ryan of NCC Group for his proper handling of the disclosure. Many thanks to our numerous financial supporters, both corporate and individuals. Without you it would not be possible to keep GnuPG in a good shape and address all the small and larger requests made by our users. Thanks. Happy hacking, Your GnuPG hackers - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBWyH4VWaOgq3Tt24GAQgAbg//Sj2CZPovZj3lAhszepFM1XypocH3XVii NhatM38Hss+8xadA7ReBvoyW3OmKjlTZn+ZqMEioOltuzidcKzs3JXgKIHgXLeK1 xaEB+hdmmKzIaXPtYRkmK+9qaR738sPOypaiRXLoEIO0cKIE5Aob8InMiuyipXRC evvrpjAARny97LNq7/2KlyFt3kWw9oZsMl6CJuU7zfBBLusFBbAMv4BMQU2+9K01 A067PvqOoN6e2z95cbY7dE2+p5myZzvS86SQNbOJW15OE04T9Uq8c7+y/Ga/lo8s hbPJlh2rxWVudSwuX1boIx7au6QIxnIwIff0A48UBm8HtA9g/lDneIBtcNiImSoK JMQefGD4zK/xHwFq3c2tZnTS9aXmcTqm+LbWOCA/keS/ciQ1PP7y9/CQLl3+/+Vu V/YIXf53ia82kz0f72WC+LcATEy0gc58RTJcx8z/pEmzY6ZVToeA8p4LGks+Zt0z Vz++/uetonpr1qOYW4Qkhj9QgBFexRrFOjIbcHVvqPPwzj/P+Mm38oVRmtnGF3di uaPxmTupRo0FVv83VFtc2PwUt+YKP9YuZp7CHlwEpzeC/44BWGSt5aXHJEPSe5To wR8oHBplRAn3xQRm1oQY41jpI9+pA8Kgnqrlb7Nde/qOY4Hdrp1o2uR6Nd+vXo/2 G47EAxKkSMY= =HzaD -----END PGP SIGNATURE-----