Mandriva Linux Security Advisory : bash (MDVSA-2015:164)
Critical Nessus Plugin ID 82417
SynopsisThe remote Mandriva Linux host is missing one or more security updates.
DescriptionUpdated bash packages fix security vulnerability :
A flaw was found in the way Bash evaluated certain specially crafted environment variables. An attacker could use this flaw to override or bypass environment restrictions to execute shell commands. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue (CVE-2014-6271).
This vulnerability can be exposed and exploited through several other pieces of software and should be considered highly critical. Please refer to the RedHat Knowledge Base article and blog post for more information.
It was found that the fix for CVE-2014-6271 was incomplete, and Bash still allowed certain characters to be injected into other environments via specially crafted environment variables. An attacker could potentially use this flaw to override or bypass environment restrictions to execute shell commands. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue (CVE-2014-7169).
Bash has been updated to version 4.2 patch level 50, which further mitigates ShellShock-type vulnerabilities. Two such issues have already been discovered (CVE-2014-6277, CVE-2014-6278).
See the RedHat article on the backward-incompatible changes introduced by the latest patch, caused by adding prefixes and suffixes to the variable names used for exporting functions. Note that the RedHat article mentions these variable names will have parentheses '()' at the end of their names, however, the latest upstream patch uses two percent signs '%%' at the end instead.
Two other unrelated security issues in the parser have also been fixed in this update (CVE-2014-7186, CVE-2014-7187).
All users and sysadmins are advised to update their bash package immediately.
SolutionUpdate the affected bash and / or bash-doc packages.