The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.
Attackers might be able to spoof the intended endpoint from a different system or process, thus gaining the same level of access as the intended endpoint. While this issue frequently involves authentication between network-based clients and servers, other types of communication channels and endpoints can have this weakness.
If an attacker can spoof the endpoint, the attacker gains all the privileges that were intended for the original endpoint.
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Effectiveness: High