#VU66857 UNIX symbolic link following in Docker - CVE-2015-3627

Vulnerability identifier: #VU66857

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2015-3627

CWE-ID: CWE-61

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Docker
Server applications / Virtualization software

Vendor: Docker Inc.

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a symlink following issue, because Docker opens the file-descriptor passed to the pid-1 process before performing the chroot. A local user can create a specially crafted symbolic link to a critical file on the system and overwrite it with privileges of the application.

Successful exploitation of this vulnerability may result in privilege escalation.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Docker: 1.6.0

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External links
https://lists.opensuse.org/opensuse-updates/2015-05/msg00023.html
https://packetstormsecurity.com/files/131835/Docker-Privilege-Escalation-Information-Disclosure.html
https://seclists.org/fulldisclosure/2015/May/28
https://groups.google.com/forum/#!searchin/docker-user/1.6.1/docker-user/47GZrihtr-4/nwgeOOFLexIJ

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.