USN-3294-1: Bash vulnerabilities

Ubuntu Security Notice USN-3294-1

17th May, 2017

bash vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 17.04
  • Ubuntu 16.10
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS

Summary

Several security issues were fixed in Bash.

Software description

  • bash - GNU Bourne Again SHell

Details

Bernd Dietzel discovered that Bash incorrectly expanded the hostname when
displaying the prompt. If a remote attacker were able to modify a hostname,
this flaw could be exploited to execute arbitrary code. This issue only
affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10.
(CVE-2016-0634)

It was discovered that Bash incorrectly handled the SHELLOPTS and PS4
environment variables. A local attacker could use this issue to execute
arbitrary code with root privileges. This issue only affected Ubuntu 14.04
LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2016-7543)

It was discovered that Bash incorrectly handled the popd command. A remote
attacker could possibly use this issue to bypass restricted shells.
(CVE-2016-9401)

It was discovered that Bash incorrectly handled path autocompletion. A
local attacker could possibly use this issue to execute arbitrary code.
This issue only affected Ubuntu 17.04. (CVE-2017-5932)

Update instructions

The problem can be corrected by updating your system to the following package version:

Ubuntu 17.04:
bash 4.4-2ubuntu1.1
Ubuntu 16.10:
bash 4.3-15ubuntu1.1
Ubuntu 16.04 LTS:
bash 4.3-14ubuntu1.2
Ubuntu 14.04 LTS:
bash 4.3-7ubuntu1.7

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

In general, a standard system update will make all the necessary changes.

References

CVE-2016-0634, CVE-2016-7543, CVE-2016-9401, CVE-2017-5932