Ubuntu 12.04 LTS / 14.04 LTS / 15.10 : exim4 vulnerabilities (USN-2933-1)
Medium Nessus Plugin ID 89962
SynopsisThe remote Ubuntu host is missing one or more security-related patches.
DescriptionIt was discovered that Exim incorrectly filtered environment variables when used with the perl_startup configuration option. If the perl_startup option was enabled, a local attacker could use this issue to escalate their privileges to the root user. This issue has been fixed by having Exim clean the complete execution environment by default on startup, including any subprocesses such as transports that call other programs. This change in behaviour may break existing installations and can be adjusted by using two new configuration options, keep_environment and add_environment. (CVE-2016-1531)
Patrick William discovered that Exim incorrectly expanded mathematical comparisons twice. A local attacker could possibly use this issue to perform arbitrary file operations as the Exim user. This issue only affected Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2014-2972).
Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
SolutionUpdate the affected exim4-daemon-custom, exim4-daemon-heavy and / or exim4-daemon-light packages.