Supply-chain tampering is the unauthorized modification of a product before it reaches the end user. In cyber security, that can mean changing hardware, firmware, software packages, packaging, or update channels so a trusted item arrives already compromised. The attacker may add a hidden implant, alter code, insert malicious dependencies, or weaken security settings during manufacturing, shipping, storage, or servicing.
This matters because defenders often trust products once they leave the vendor. A tampered device can bypass normal malware detection, steal credentials, intercept data, or create covert access that survives resets. Common defenses include secure sourcing, chain-of-custody controls, signed firmware and software, package verification, tamper-evident seals, inspection, and attestation checks that confirm a device or update has not been altered. Supply-chain tampering is dangerous because it turns trusted technology into an attack path before the user even powers it on.