The Secure attribute for sensitive cookies in HTTPS sessions is not set.
Always set the secure attribute when the cookie should be sent via HTTPS only.
Omitting the secure flag makes it possible for the user agent to send the cookies in plaintext over an HTTP session.
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