CVE-2019-12578: Improper Neutralization of Argument Delimiters in a Command

A vulnerability in the London Trust Media Private Internet Access (PIA) VPN Client v82 for Linux could allow an authenticated, local attacker to run arbitrary code with elevated privileges. The openvpn_launcher.64 binary is setuid root. This binary executes /opt/pia/openvpn-64/openvpn, passing the parameters provided from the command line. Care was taken to programmatically disable potentially dangerous openvpn parameters; however, the --route-pre-down parameter can be used. This parameter accepts an arbitrary path to a script/program to be executed when OpenVPN exits. The --script-security parameter also needs to be passed to allow for this action to be taken, and --script-security is not currently in the disabled parameter list. A local unprivileged user can pass a malicious script/binary to the --route-pre-down option, which will be executed as root when openvpn is stopped.