  This letter studies an emerging wireless communication intervention problem
at the physical layer, where a legitimate spoofer aims to spoof a malicious
link from Alice to Bob, by replacing Alice's transmitted source message with
its target message at Bob side. From an information-theoretic perspective, we
are interested in characterizing the maximum achievable spoofing rate of this
new spoofing channel, which is equivalent to the maximum achievable rate of the
target message at Bob, under the condition that Bob cannot decode the source
message from Alice. We propose a novel combined spoofing approach, where the
spoofer sends its own target message, combined with a processed version of the
source message to cancel the source message at Bob. For both cases when Bob
treats interference as noise (TIN) or applies successive interference
cancelation (SIC), we obtain the maximum achievable spoofing rates by
optimizing the power allocation between the target and source messages at the
spoofer.
