Memory-resident software runs in a device’s volatile RAM instead of relying on a conventional executable file stored on disk. It may run as part of an existing process, making it harder to distinguish from legitimate activity. Because RAM is generally cleared when a device shuts down or reboots, evidence of the software can disappear.
In cyber security, memory-resident malware can evade defenses that focus on scanning files or looking for newly opened network ports. For example, an implant on a firewall may alter a trusted service while leaving few obvious disk artifacts. Defenders should monitor process behavior and administrative activity, compare device state with known-good baselines, and preserve relevant logs and volatile evidence before rebooting or making changes.