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Message-Id: <20150801172434.746C54D8BEC@smtpvbsrv1.mitre.org>
Date: Sat, 1 Aug 2015 13:24:34 -0400 (EDT)
From: cve-assign@...re.org
To: carnil@...ian.org
Cc: cve-assign@...re.org, oss-security@...ts.openwall.com
Subject: Re: CVE Request: devscripts: licensecheck: arbitrary shell command injection
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Hash: SHA256
> licensecheck is prone to arbitrary shell command injection via
> shell metacharacters in filenames
>
> https://bugs.debian.org/794260
> https://anonscm.debian.org/cgit/collab-maint/devscripts.git/commit/?id=c0687bcde23108dd42e146573c368b6905e6b8e8
Use CVE-2015-5704 for the issue involving shell metacharacters that
was fixed in c0687bcde23108dd42e146573c368b6905e6b8e8.
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=794260#8
>
> (If the variable were expanded by shell, command injection wouldn't be
> even possible. You could still exploit argument injection, but that's
> less exciting.)
Yes, but argument injection is within the scope of CVE and seems to be
relevant even in the patched code, i.e.,
% touch -- -C
% ln -s /etc/passwd magic.mgc
% ls -l /etc/passwd
-rw-r--r-- 1 root root 1388 Jul 16 14:47 /etc/passwd
% licensecheck -- *C
/usr/bin/licensecheck warning: cannot parse file '-C' with mime type ''
% ls -l /etc/passwd
-rw-r--r-- 1 0 root 248 Aug 1 13:07 /etc/passwd
In other words, we don't believe it's intentional behavior for
licensecheck to operate on arbitrary files that have '-' at the
beginning of their names, and use these names to construct unsafe
command lines for the file program. The new spawn section perhaps
should begin with
spawn(exec => ['file', '--brief', '--mime', '--dereference', '--', $file],
instead. Use CVE-2015-5705 for this argument injection vulnerability.
For now, we'll leave the open question of whether the file program
should be following symlinks when creating a magic.mgc file in
response to the -C option. Possibly file was supposed to be resilient
in the face of unsafe directories, e.g., a legitimate user shouldn't
need to be concerned about file overwrites when running "file *" in a
directory where a local attacker has created a -C file and a symlink
named magic.mgc. However, maybe the legitimate user is supposed to
know to type "file -- *" whenever the directory might contain leading
'-' characters in filenames. And maybe the legitimate user who
directly enters -C on the command line actually wants magic.mgc to be
created in the location specified by the symlink. It doesn't seem
possible to decide whether there's a file vulnerability here without
clarification from the author of file.
- --
CVE assignment team, MITRE CVE Numbering Authority
M/S M300
202 Burlington Road, Bedford, MA 01730 USA
[ PGP key available through http://cve.mitre.org/cve/request_id.html ]
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