Adversaries may compromise third-party Virtual Private Servers (VPSs) that can be used during targeting. There exist a variety of cloud service providers that will sell virtual machines/containers as a service. Adversaries may compromise VPSs purchased by third-party entities. By compromising a VPS to use as infrastructure, adversaries can make it difficult to physically tie back operations to themselves.
Compromising a VPS for use in later stages of the adversary lifecycle, such as Command and Control, can allow adversaries to benefit from the ubiquity and trust associated with higher reputation cloud service providers as well as that added by the compromised third-party.
This technique cannot be easily mitigated with preventive controls since it is based on behaviors performed outside of the scope of enterprise defenses and controls.
Once adversaries have provisioned software on a compromised VPS (ex: for use as a command and control server), internet scans may reveal VPSs that adversaries have compromised. Consider looking for identifiable patterns such as services listening, certificates in use, SSL/TLS negotiation features, or other response artifacts associated with adversary C2 software.
Much of this activity will take place outside the visibility of the target organization, making detection of this behavior difficult. Detection efforts may be focused on related stages of the adversary lifecycle, such as during Command and Control.