Redirected standard input is input data sent to a process from a source other than the keyboard. In Windows, that source can be a file, a pipe, another process, or a programmatic handle. The process still reads from its normal input stream, but the bytes arrive through a different path.
In cyber security, this matters because attackers can use redirected input to feed commands, payloads, or shellcode-like data into console applications without relying on obvious memory-write APIs. That can make malicious activity look like routine automation or scripting. Defenders should watch for unusual input sources, console processes receiving unexpected streams, and follow-on behavior such as memory protection changes or execution transfer. By correlating these events, security tools can spot abuse even when classic injection indicators are absent.