Peer relay is a communication path in which one compromised device passes data to another nearby device for onward transfer. Instead of sending stolen information directly to an attacker server, the malware uses a local device-to-device hop as a relay. This can help an intrusion survive when the victim device has no stable internet access, is offline, or is tightly filtered by network defenses.
In cyber attacks, peer relay can support exfiltration, command delivery, or covert synchronization between infected devices. It is especially relevant in mobile malware, where Bluetooth, Wi-Fi Direct, hotspot features, or other local links may be abused as part of a hidden chain of compromise. For defenders, the key risk is that standard perimeter monitoring may miss the first stage of data movement. Detection therefore depends on endpoint telemetry, unusual local wireless activity, permission abuse, and controls that limit unnecessary peer-to-peer communication.