Re: [PATCH] Add 2010, 2012 Security notices to SECURITY
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From: Russ A. <ea...@ey...> - 2021-01-17 22:34:41
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Spenser Truex <tr...@eq...> writes: > From website > http://pizzashack.org/rssh/security.shtml More recently, you should also be aware of CVE-2019-1000018, CVE-2019-3464, and CVE-2019-3463. It turns out to be extremely difficult to do what rssh is attempting to do because the underlying software that it is trying to protect does not cooperate very well (and in some cases could be said to be actively hostile). New mechanisms of bypassing its intended restrictions keep cropping up. For example, I'm fairly sure the CVS support is not secure, although I have not put the effort into figuring out how to break it. You should probably consider rssh deprecated and think about alternatives. My attempts to clean up the last few rounds of problems produced a ton of collateral damage, and I've personally stopped trying to maintain rssh in Debian because I'm not confident that I can make it secure. Here are the most recent changelogs from the Debian package, which should provide a feel for the scope of the problem. This also includes other potential security issues that never received a CVE: rssh (2.3.4-12) unstable; urgency=high * The fix for the scp security vulnerability in 2.3.4-9 combined with the regression fix in 2.3.4-10 rejected the -pf and -pt options, which are sent by libssh2's scp support. Add support for those variants. (LP #1815935) -- Russ Allbery <rr...@de...> Mon, 18 Feb 2019 18:58:27 -0800 rssh (2.3.4-11) unstable; urgency=high * The fix for the scp security vulnerability in 2.3.4-9 introduced a regression that blocked scp of multiple files from a server using rssh. Based on further analysis of scp's command-line parsing, relax the check to require the server command contain -f or -t, which should deactivate scp's support for remote files. (Closes: #921655) -- Russ Allbery <rr...@de...> Sun, 10 Feb 2019 11:17:28 -0800 rssh (2.3.4-10) unstable; urgency=high * Also reject rsync --daemon and --config command-line options, which can be used to run arbitrary commands. Thanks, Nick Cleaton. (CVE-2019-3463) * Unset the HOME environment variable when running rsync to prevent popt (against which rsync is linked) from loading a ~/.popt configuration file, which can run arbitrary commands on the server or redefine command-line options to bypass argument checking. Thanks, Nick Cleaton. (CVE-2019-3464) * Do not stop checking the rsync command line at --, since this can be an argument to some other option and later arguments may still be interpreted as options. In the few cases where one needs to rsync to files named things like --rsh, the client can use ./--rsh instead. Thanks, Nick Cleaton. * Remove now-unused variables from the rsync validation patch. -- Russ Allbery <rr...@de...> Sat, 02 Feb 2019 10:59:47 -0800 rssh (2.3.4-9) unstable; urgency=high * Validate the allowed scp command line and only permit the flags used in server mode and only a single argument, to attempt to prevent use of ssh options to run arbitrary code on the server. This will break scp -3 to a system running rssh, which seems like an acceptable loss. (Closes: #919623, CVE-2019-1000018) * Tighten validation of the rsync command line to require --server be the first argument, which should prevent initiation of an outbound rsync command from the server, which in turn might allow execution of arbitrary code via ssh configuration similar to scp. * Add validation of the server command line after chroot when chroot is enabled. Prior to this change, dangerous argument filtering was not done when chroot was configured, allowing remote code execution inside the chroot in some configurations via the previous two bugs and via the mechanisms in CVE-2012-2251 and CVE-2012-2252. * Document that the cvs server-side dangerous option filtering is probably insufficient and should not be considered secure. -- Russ Allbery <rr...@de...> Mon, 28 Jan 2019 21:03:59 -0800 -- Russ Allbery (ea...@ey...) <https://www.eyrie.org/~eagle/> |