CVE-2015-5252
First published: Thu Dec 10 2015(Updated: )
As per samba upstream advisory: All versions of Samba from 3.0.0 to 4.3.2 inclusive are vulnerable to a bug in symlink verification, which under certain circumstances could allow client access to files outside the exported share path. If a Samba share is configured with a path that shares a common path prefix with another directory on the file system, the smbd daemon may allow the client to follow a symlink pointing to a file or directory in that other directory, even if the share parameter "wide links" is set to "no" (the default). For example. Given two directories on the file system: /share/ /share1/ If a Samba share is created as follows: [sharename] path = /share wide links = no Then a symlink with the path /share/symlink -> /share1/file would be followed by smbd, due to the fact that only the string "/share" is checked to see if it matches the target path. This means a path that starts with "/share", such as "/share1" will also match. The following mitigation was suggested by upstream: Ensure all exported share paths do not share base path names with other directories on the file system. Please note, setting the smb.conf variable "follow symlinks = no" is *NOT* a workaround for this problem, as this only prohibits smbd from following a symlink at the end of a path. A symlink could be created that points to the directory which shares a base path name instead, and smbd would still follow that link. For example, with the above share definition, given a symlink of: /share/symlink -> /share1 a client could send a relative path such as "symlink/file", which would still be followed by smbd as the end component "file" of "symlink/file" is *NOT* a symlink, and so is not affected by "follow symlinks = no".
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Samba Samba | >=3.0.0<4.1.22 | |
| Samba Samba | >=4.2.0<4.2.7 | |
| Samba Samba | >=4.3.0<4.3.3 | |
| Canonical Ubuntu Linux | =12.04 | |
| Canonical Ubuntu Linux | =14.04 | |
| Canonical Ubuntu Linux | =15.04 | |
| Canonical Ubuntu Linux | =15.10 | |
| Debian Debian Linux | =7.0 | |
| Debian Debian Linux | =8.0 | |
| redhat/samba | <4.1.22 | 4.1.22 |
| redhat/samba | <4.2.7 | 4.2.7 |
| redhat/samba | <4.3.3 | 4.3.3 |
Never miss a vulnerability like this again
Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.
Reference Links
- http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174076.html
- http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174391.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00019.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00020.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00032.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00033.html
- http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00002.html
- http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00017.html
- http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00042.html
- http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00046.html
- http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00047.html
- http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00048.html
- http://www.debian.org/security/2016/dsa-3433
- http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
- http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
- http://www.securityfocus.com/bid/79733
- http://www.securitytracker.com/id/1034493
- http://www.ubuntu.com/usn/USN-2855-1
- http://www.ubuntu.com/usn/USN-2855-2
- https://bugzilla.redhat.com/show_bug.cgi?id=1290288
- https://git.samba.org/?p=samba.git;a=commit;h=4278ef25f64d5fdbf432ff1534e275416ec9561e
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05115993
- https://security.gentoo.org/glsa/201612-47
- https://www.samba.org/samba/security/CVE-2015-5252.html
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1292069
- https://git.samba.org/?p=samba.git;a=commitdiff;h=4278ef25f64d5fdbf432ff1534e275416ec9561e
- https://rhn.redhat.com/errata/RHSA-2016-0010.html
- https://rhn.redhat.com/errata/RHSA-2016-0011.html
- https://rhn.redhat.com/errata/RHSA-2016-0006.html
- https://rhn.redhat.com/errata/RHSA-2016-0016.html
- https://rhn.redhat.com/errata/RHSA-2016-0015.html
- https://git.samba.org/?p=samba.git%3Ba=commit%3Bh=4278ef25f64d5fdbf432ff1534e275416ec9561e
- collector/nvd-index
- agent/type
- agent/first-publish-date
- agent/softwarecombine
- collector/mitre-cve
- source/MITRE
- agent/severity
- agent/last-modified-date
- agent/references
- agent/author
- agent/remedy
- agent/weakness
- agent/event
- agent/description
- collector/redhat-bugzilla
- source/Red Hat
- alias/CVE-2015-5252
- agent/software-canonical-lookup
- agent/tags
- agent/trending
- vendor/samba
- canonical/samba samba
- version/samba samba/3.0.0
- version/samba samba/4.2.0
- version/samba samba/4.3.0
- vendor/canonical
- canonical/canonical ubuntu linux
- version/canonical ubuntu linux/12.04
- version/canonical ubuntu linux/14.04
- version/canonical ubuntu linux/15.04
- version/canonical ubuntu linux/15.10
- vendor/debian
- canonical/debian debian linux
- version/debian debian linux/7.0
- version/debian debian linux/8.0
- package-manager/redhat