Date: Sun, 26 Sep 2021 08:52:50 -0600 (MDT) From: Damien Miller <djm@....openbsd.org> To: oss-security@...ts.openwall.com Subject: Announce: OpenSSH 8.8 released OpenSSH 8.8 has just been released. It will be available from the mirrors listed at https://www.openssh.com/ shortly. OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs, tested snapshots or donated to the project. More information on donations may be found at: https://www.openssh.com/donations.html Future deprecation notice ========================= A near-future release of OpenSSH will switch scp(1) from using the legacy scp/rcp protocol to using SFTP by default. Legacy scp/rcp performs wildcard expansion of remote filenames (e.g. "scp host:* .") through the remote shell. This has the side effect of requiring double quoting of shell meta-characters in file names included on scp(1) command-lines, otherwise they could be interpreted as shell commands on the remote side. This creates one area of potential incompatibility: scp(1) when using the SFTP protocol no longer requires this finicky and brittle quoting, and attempts to use it may cause transfers to fail. We consider the removal of the need for double-quoting shell characters in file names to be a benefit and do not intend to introduce bug- compatibility for legacy scp/rcp in scp(1) when using the SFTP protocol. Another area of potential incompatibility relates to the use of remote paths relative to other user's home directories, for example - "scp host:~user/file /tmp". The SFTP protocol has no native way to expand a ~user path. However, sftp-server(8) in OpenSSH 8.7 and later support a protocol extension "expand-path@...nssh.com" to support this. Security ======== sshd(8) from OpenSSH 6.2 through 8.7 failed to correctly initialise supplemental groups when executing an AuthorizedKeysCommand or AuthorizedPrincipalsCommand, where a AuthorizedKeysCommandUser or AuthorizedPrincipalsCommandUser directive has been set to run the command as a different user. Instead these commands would inherit the groups that sshd(8) was started with. Depending on system configuration, inherited groups may allow AuthorizedKeysCommand/AuthorizedPrincipalsCommand helper programs to gain unintended privilege. Neither AuthorizedKeysCommand nor AuthorizedPrincipalsCommand are enabled by default in sshd_config(5). Potentially-incompatible changes ================================ This release disables RSA signatures using the SHA-1 hash algorithm by default. This change has been made as the SHA-1 hash algorithm is cryptographically broken, and it is possible to create chosen-prefix hash collisions for <USD$50K  For most users, this change should be invisible and there is no need to replace ssh-rsa keys. OpenSSH has supported RFC8332 RSA/SHA-256/512 signatures since release 7.2 and existing ssh-rsa keys will automatically use the stronger algorithm where possible. Incompatibility is more likely when connecting to older SSH implementations that have not been upgraded or have not closely tracked improvements in the SSH protocol. For these cases, it may be necessary to selectively re-enable RSA/SHA1 to allow connection and/or user authentication via the HostkeyAlgorithms and PubkeyAcceptedAlgorithms options. For example, the following stanza in ~/.ssh/config will enable RSA/SHA1 for host and user authentication for a single destination host: Host old-host HostkeyAlgorithms +ssh-rsa PubkeyAcceptedAlgorithms +ssh-rsa We recommend enabling RSA/SHA1 only as a stopgap measure until legacy implementations can be upgraded or reconfigured with another key type (such as ECDSA or Ed25519).  "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and Application to the PGP Web of Trust" Leurent, G and Peyrin, T (2020) https://eprint.iacr.org/2020/014.pdf Changes since OpenSSH 8.7 ========================= This release is motivated primarily by the above deprecation and security fix. New features ------------ * ssh(1): allow the ssh_config(5) CanonicalizePermittedCNAMEs directive to accept a "none" argument to specify the default behaviour. Bugfixes -------- * scp(1): when using the SFTP protocol, continue transferring files after a transfer error occurs, better matching original scp/rcp behaviour. * ssh(1): fixed a number of memory leaks in multiplexing, * ssh-keygen(1): avoid crash when using the -Y find-principals command. * A number of documentation and manual improvements, including bz#3340, PR#139, PR#215, PR#241, PR#257 Portability ----------- * ssh-agent(1): on FreeBSD, use procctl to disable ptrace(2) * ssh(1)/sshd(8): some fixes to the pselect(2) replacement compatibility code. bz#3345 Checksums: ========== - SHA1 (openssh-8.8.tar.gz) = 732947082a8998047e839cc0b4c066bf0a7e1a5b - SHA256 (openssh-8.8.tar.gz) = AngyrPSQH255hnzU1l7y+LlVAUNcGWtuYQIFEl22nRo= - SHA1 (openssh-8.8p1.tar.gz) = 1eb964897a4372f6fb96c7effeb509ec71c379c9 - SHA256 (openssh-8.8p1.tar.gz) = RZCJDqm7ms5Pca4zF4WjpYIyMkNRYZYO1fyGWI8zH+k= Please note that the SHA256 signatures are base64 encoded and not hexadecimal (which is the default for most checksum tools). The PGP key used to sign the releases is available from the mirror sites: https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc Please note that the OpenPGP key used to sign releases has been rotated for this release. The new key has been signed by the previous key to provide continuity. Reporting Bugs: =============== - Please read https://www.openssh.com/report.html Security bugs should be reported directly to openssh@...nssh.com
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