Anti-Spyware Signatures are designed to detect and block known malware, including those that attempt to establish command-and-control (C2) connections with external servers. When an endpoint inside an organization is infected with known malware, the anti-spyware signatures on the firewall can recognize the malicious traffic and prevent the connection from being established. This mechanism works by inspecting traffic against a database of known spyware and malware signatures, thereby stopping the malware from communicating with its C2 server.