oss-sec mailing list archives
Re: CVE Request: ro bind mount bypass using user namespaces
From: Kenton Varda <kenton () sandstorm io>
Date: Wed, 13 Aug 2014 00:18:40 -0700
I'm happy with however you want to assign credit here, but for clarification: I actually observed that all these bits could be modified. My first observation was with nosuid. But, I thought they were just the same issue applied to different bits in the same bitfield. I specifically used the RO bit in my PoC. Looking back, it looks like I didn't explicitly point out which other bits were affected, but Eric quickly re-discovered them, and also discovered from reviewing the code that the other bits had even fewer guards against modification compared to the RO bit. Andrew Lutomirski has further discovered that this problem can be used to escalate a regular user to root privileges on typical Linux configurations, independent of any sandboxing effort. Thanks, -Kenton On Tue, Aug 12, 2014 at 10:49 PM, <cve-assign () mitre org> wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 We are assigning two CVE IDs because the available information is that there were two discoverers. Even if the discoverer information is later clarified, there will still be these two CVE IDs.https://git.kernel.org/cgit/linux/kernel/git/ebiederm/user-namespace.git/commit/?h=for-linus&id=db181ce011e3c033328608299cd6fac06ea50130Kenton Varda <kenton () sandstorm io> discovered that by remounting a read-only bind mount read-only in a user namespace the MNT_LOCK_READONLY bit would be cleared, allowing an unprivileged user to the remount a read-only mount read-write.Use CVE-2014-5206.https://git.kernel.org/cgit/linux/kernel/git/ebiederm/user-namespace.git/commit/?h=for-linus&id=9566d6742852c527bf5af38af5cbb878dad75705While investigating the issue where in "mount --bind -oremount,ro ..." would result in later "mount --bind -oremount,rw" succeeding even if the mount started off locked I realized that there are several additional mount flags that should be locked and are not.Use CVE-2014-5207. - -- 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 ] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (SunOS) iQEcBAEBAgAGBQJT6vjTAAoJEKllVAevmvmsEI4H+wWrFmadZJwDhgU8i5IfiVIl Oz/iPTeSCelGIH6BA5GAMbaEmMUf/ay0Jpa31y6MhOiw1KMsGGFvzGkLoy3Pb/T5 G682hBmQbZD1OnBdk3z2EnMd5i0/B3kzc1rXi4m9QJcmi216xnJnD0+lEVbRj5nf jruRJplaRiwYuXszZSWhAOBVMFb5MJ/4aNmUkKdpiywQjOWhykgjNNyxXby9Rxpo AkoLecJPn/IJ4mRmLTp3vo1x/GZUXmXFvKfsJdB5Ps+kOnX7ptMyap4GTjSvXcIc FSJ9Zfad0iAnflEQTAKEVHFu5vSzbUdWVC+qMapVjZXRnku8y3UzYJVEvqQDUTc= =Qzne -----END PGP SIGNATURE-----
Current thread:
- CVE Request: ro bind mount bypass using user namespaces Kenton Varda (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 13)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces cve-assign (Aug 12)
- Re: CVE Request: ro bind mount bypass using user namespaces Kenton Varda (Aug 13)
- Re: CVE Request: ro bind mount bypass using user namespaces Yves-Alexis Perez (Aug 13)
- Re: CVE Request: ro bind mount bypass using user namespaces Sven Kieske (Aug 13)
- <Possible follow-ups>
- Re: CVE Request: ro bind mount bypass using user namespaces Vitaly Nikolenko (Aug 14)
- Re: CVE Request: ro bind mount bypass using user namespaces Andy Lutomirski (Aug 12)