Subject: [ASA-201701-19] docker: privilege escalation

Arch Linux Security Advisory ASA-201701-19
==========================================

Severity: High
Date    : 2017-01-13
CVE-ID  : CVE-2016-9962
Package : docker
Type    : privilege escalation
Remote  : No
Link    : https://security.archlinux.org/AVG-133

Summary
=======

The package docker before version 1:1.12.6-1 is vulnerable to privilege
escalation.

Resolution
==========

Upgrade to 1:1.12.6-1.

# pacman -Syu "docker>=1:1.12.6-1"

The problem has been fixed upstream in version 1.12.6.

Workaround
==========

None.

Description
===========

The runc component used by `docker exec` feature of docker allowed
additional container processes to be ptraced by the pid 1 of the
container. This allows the main processes of the container, if running
as root, to gain low-level access to these new processes during
initialization. An attacker can, depending on the nature of the
incoming process, leverage this to elevate access to the host. This
ranges from accessing host content through the file descriptors of the
incoming process to, potentially, a complete container escape by
leveraging memory access or syscall interception.

Impact
======

A local unprivileged attacker when running as root inside a docker
container is able to access the host filesystem leading to privilege
escalation.

References
==========

https://bugs.archlinux.org/task/52493
https://github.com/opencontainers/runc/commit/50a19c6ff828c58e5dab13830bd3dacde268afe5
https://bugzilla.suse.com/show_bug.cgi?id=1012568
https://github.com/docker/docker/compare/v1.12.5...v1.12.6
https://www.mail-archive.com/fulldisclosure@seclists.org/msg04165.html
https://security.archlinux.org/CVE-2016-9962