Werner Koch wk at gnupg.org
Fri Jun 8 15:40:55 CEST 2018

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Hello!

We are pleased to announce the availability of a new GnuPG release: version 2.2.8. This version fixes a critical security bug and comes with some other minor changes.

Impact

All current GnuPG versions are affected on all platforms.

All mail clients and other applications which make use of GPG but are not utilizing the GPGME library might be affected.

The OpenPGP protocol allows to include the file name of the original input file into a signed or encrypted message. During decryption and verification the GPG tool can display a notice with that file name. The displayed file name is not sanitized and as such may include line feeds or other control characters. This can be used inject terminal control sequences into the out and, worse, to fake the so-called status messages. These status messages are parsed by programs to get information from gpg about the validity of a signature and an other parameters. Status messages are created with the option “–status-fd N” where N is a file descriptor. Now if N is 2 the status messages and the regular diagnostic messages share the stderr output channel. By using a made up file name in the message it is possible to fake status messages. Using this technique it is for example possible to fake the verification status of a signed mail.

Although GnuPG takes great care to sanitize all diagnostic and status output, the case at hand was missed but finally found and reported by Marcus Brinkmann. CVE-2018-12020 was assigned to this bug; GnuPG tracks it at https://dev/gnupg.org/T4012\.

Solution

If your application uses GPGME your application is safe. Fortunately most modern mail readers use GPGME, including GpgOL and KMail. Mutt users should make sure to use "set crypt_use_gpgme".

If you are parsing GnuPG status output and you use a dedicated file descriptor with --status-fd you are safe. A dedicated file descriptor is one that is not shared with the log output. The log output defaults to stderr (2) but may be a different if the option --logger-fd is used.

If you are not using --verbose you are safe. But take care: --verbose might be specified in the config file. As a short term mitigation or if you can’t immediately upgrade to the latest versions, you can add –no-verbose to the invocation of gpg.

Another short term mitigation is to redirect the log output to a different file: For example "–log-file /dev/null".

The suggested solution is to update to GnuPG 2.2.8 or a vendor provided update of their GnuPG version.

To check whether the bug has been fixed you may use the simple test at the end of this mail [1].

About GnuPG

The GNU Privacy Guard (GnuPG) is a complete and free implementation of the OpenPGP standard which is commonly abbreviated as PGP.

GnuPG allows to encrypt and sign data and communication, features a versatile key management system as well as access modules for public key directories. GnuPG itself is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries making use of GnuPG are available. As an Universal Crypto Engine GnuPG provides support for S/MIME and Secure Shell in addition to OpenPGP.

GnuPG is Free Software (meaning that it respects your freedom). It can be freely used, modified and distributed under the terms of the GNU General Public License.

Noteworthy changes in version 2.2.8

* gpg: Decryption of messages not using the MDC mode will now lead to a hard failure even if a legacy cipher algorithm was used. The option --ignore-mdc-error can be used to turn this failure into a warning. Take care: Never use that option unconditionally or without a prior warning.

* gpg: The MDC encryption mode is now always used regardless of the cipher algorithm or any preferences. For testing --rfc2440 can be used to create a message without an MDC.

* gpg: Sanitize the diagnostic output of the original file name in verbose mode. [#4012,CVE-2018-12020]

* gpg: Detect suspicious multiple plaintext packets in a more reliable way. [#4000]

* gpg: Fix the duplicate key signature detection code. [#3994]

* gpg: The options --no-mdc-warn, --force-mdc, --no-force-mdc, –disable-mdc and --no-disable-mdc have no more effect.

* agent: Add DBUS_SESSION_BUS_ADDRESS and a few other envvars to the list of startup environment variables. [#3947]

Getting the Software

Please follow the instructions found at https://gnupg.org/download/\ or read on:

GnuPG 2.2.8 may be downloaded from one of the GnuPG mirror sites or direct from its primary FTP server. The list of mirrors can be found at https://gnupg.org/download/mirrors.html\. Note that GnuPG is not available at ftp.gnu.org.

The GnuPG source code compressed using BZIP2 and its OpenPGP signature are available here:

https://gnupg.org/ftp/gcrypt/gnupg/gnupg-2.2.8.tar.bz2 (6477k) https://gnupg.org/ftp/gcrypt/gnupg/gnupg-2.2.8.tar.bz2.sig

An installer for Windows without any graphical frontend except for a very minimal Pinentry tool is available here:

https://gnupg.org/ftp/gcrypt/binary/gnupg-w32-2.2.8_20180608.exe (3916k) https://gnupg.org/ftp/gcrypt/binary/gnupg-w32-2.2.8_20180608.exe.sig

The source used to build the Windows installer can be found in the same directory with a “.tar.xz” suffix. A new Gpg4win installer featuring this version of GnuPG will be available soon.

Checking the Integrity

In order to check that the version of GnuPG which you are going to install is an original and unmodified one, you can do it in one of the following ways:

* If you already have a version of GnuPG installed, you can simply verify the supplied signature. For example to verify the signature of the file gnupg-2.2.8.tar.bz2 you would use this command:

 gpg --verify gnupg-2.2.8.tar.bz2.sig gnupg-2.2.8.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 gnupg-2.2.8.tar.bz2, you run the command like this:

 sha1sum gnupg-2.2.8.tar.bz2

and check that the output matches the next line:

d87553a125832ea90e8aeb3ceeecf24f88de56fb gnupg-2.2.8.tar.bz2 3126ec2b7005063cbff95792208796dfa42c2a22 gnupg-w32-2.2.8_20180608.tar.xz 231b29631647328934a35f8c6baa483e7594e26a gnupg-w32-2.2.8_20180608.exe

Internationalization

This version of GnuPG has support for 26 languages with Chinese, Czech, French, German, Japanese, Norwegian, Russian, and Ukrainian being almost completely translated.

Documentation and Support

If you used GnuPG in the past you should read the description of changes and new features at doc/whats-new-in-2.1.txt or online at

https://gnupg.org/faq/whats-new-in-2.1.html

The file gnupg.info has the complete reference manual of the system. Separate man pages are included as well but they miss some of the details availabale only in thee manual. The manual is also available online at

https://gnupg.org/documentation/manuals/gnupg/

or can be downloaded as PDF at

https://gnupg.org/documentation/manuals/gnupg.pdf .

The chapters on gpg-agent, gpg and gpgsm include information on how to set up the whole thing. You may also want to search the GnuPG mailing list archives or ask on the gnupg-users mailing list for advise on how to solve problems. Most of the new features are around for several years and thus enough public experience is available.

Please consult the archive of the gnupg-users mailing list before reporting a bug: https://gnupg.org/documentation/mailing-lists.html\. We suggest to send bug reports for a new release to this list in favor of filing a bug at https://bugs.gnupg.org\. If you need commercial support check out https://gnupg.org/service.html\.

If you are a developer and you need a certain feature for your project, please do not hesitate to bring it to the gnupg-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 one contractor. Both work exclusively on GnuPG and closely related software like Libgcrypt, GPGME, and GPA. We are planning to extend our team again and to help developers to improve integration of crypto in their applications.

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.

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

p.s. This is an announcement only mailing list. Please send replies only to the gnupg-users’at’gnupg.org mailing list.

p.p.s List of Release Signing Keys:

To guarantee that a downloaded GnuPG version has not been tampered by malicious entities we provide signature files for all tarballs and binary versions. The keys are also signed by the long term keys of their respective owners. Current releases are signed by one or more of these four keys:

rsa2048 2011-01-12 [expires: 2019-12-31] Key fingerprint = D869 2123 C406 5DEA 5E0F 3AB5 249B 39D2 4F25 E3B6 Werner Koch (dist sig)

rsa2048 2014-10-29 [expires: 2019-12-31] Key fingerprint = 46CC 7308 65BB 5C78 EBAB ADCF 0437 6F3E E085 6959 David Shaw (GnuPG Release Signing Key) <dshaw ‘at’ jabberwocky.com>

rsa2048 2014-10-29 [expires: 2020-10-30] Key fingerprint = 031E C253 6E58 0D8E A286 A9F2 2071 B08A 33BD 3F06 NIIBE Yutaka (GnuPG Release Key) <gniibe ‘at’ fsij.org>

rsa3072 2017-03-17 [expires: 2027-03-15] Key fingerprint = 5B80 C575 4298 F0CB 55D8 ED6A BCEF 7E29 4B09 2E28 Andre Heinecke (Release Signing Key)

The keys are available at https://gnupg.org/signature\_key.html\ and in any recently released GnuPG tarball in the file g10/distsigkey.gpg . Note that this mail has been signed by a different key. ===========

[1] If you want to test whether you are affected by this bug, remove the indentation from the following block

-----BEGIN PGP MESSAGE-----

jA0EBwMC1pW2pqoYvbXl0p4Bo5z/v7PXy7T1BY/KQxWaE9uTBRbf4no64/+5YYzX +BVNqP+82aBFYXEsD9x1vGuYwofQ4m/q/WcQDEPXhRyzU+4yiT3EOuG7sTTaQR3b 8xAn2Qtpyq5tO7k9CN6dasaXKSduXVmFUqzgU+W9WaTLOKNDFw6FYV3lnOoPtFcX rzhh2opkX9Oh/5DUkZ6YmUIX3j/A0z+59/qNO1i2hQ== =zswl -----END PGP MESSAGE-----

and pass to this pipeline

gpg --no-options -vd 2>&1 | grep ‘^\[GNUPG:] INJECTED’

If you get some output you are using a non-fixed version.

–

Please read: Daniel Ellsberg - The Doomsday Machine

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