Webmin Package Updates RCE

This module exploits an arbitrary command injection in Webmin
versions prior to 1.997.

Webmin uses the OS package manager (`apt`, `yum`, etc.) to perform
package updates and installation. Due to a lack of input
sanitization, it is possibe to inject arbitrary command that will be
concatenated to the package manager call.

This exploit requires authentication and the account must have access
to the Software Package Updates module.