An internal network can include a plurality of linked internal nodes, each internal node being configured to communicate with other internal nodes or with one or more external servers over an external network. The internal network can analyze the configuration of the internal nodes and the network traffic between internal nodes of the internal network and external servers. Based on the analysis, a network vulnerability score measuring the vulnerability of the internal network to attack can be determined. If the vulnerability score is below a threshold, the internal network can be isolated from the external network, for example by preventing internal nodes from communicating with or over the external network.