GNU Bash Environment Variable Handling Shell Remote Command Execution Vulnerability (SIP Check)

Summary
This host is installed with GNU Bash Shell and is prone to remote command execution vulnerability.
Impact
Successful exploitation will allow remote or local attackers to inject shell commmands, allowing local privilege escalation or remote command execution depending on the application vector. Impact Level: Application
Solution
Apply the patch or upgrade to latest version, For updates refer to http://www.gnu.org/software/bash/
Insight
GNU bash contains a flaw that is triggered when evaluating environment variables passed from another environment. After processing a function definition, bash continues to process trailing strings. The exec module in Kamailio, Opensips and propably every other SER fork passes the received SIP headers as environment variables to the invoking shell. A proxy is vulnerable using any of the exec funtions and has the 'setvars' parameter set to the default value '1'.
Affected
GNU Bash through 4.3
Detection
Send a crafted command via SIP INVITE request and check remote command execution.
References