An update server is a system that provides software updates and related configuration to client devices. Applications may contact it to learn which version to install, where to download update files, or how to apply them. Because devices often trust this process automatically, the server is a critical part of the software supply chain.
Attackers who alter an update server or its configuration may redirect clients to malicious downloads or tamper with legitimate updates. This can expose devices even when the software itself has no known vulnerability, although a download being offered does not prove it was installed or executed. Defenses include restricting and auditing access to update infrastructure, monitoring configuration changes, and verifying update signatures and file integrity on clients.