Which of the following allows an exploit to go undetected by the operating system?

Memory injection allows an exploit to go undetected by the operating system because it involves injecting malicious code directly into the memory space of a legitimate, running process. This bypasses many traditional security controls that monitor file system changes or new process creation, as the malicious code executes within an already trusted process. Firmware vulnerabilities are flaws in the low-level software that controls hardware, which can be exploited but don't inherently make the exploit undetectable by the OS once it's running. Side loading is the practice of installing applications from unofficial sources, which increases risk but doesn't guarantee undetectability. Encrypted payloads are designed to hide their content during transit or storage, but once decrypted and executed, the OS can still detect their malicious activity.