Juniper ATP Cloud performs cache lookup to see if the file is seen already and known to be malicious and dynamic analysis to see what happens if you execute the file in a real environment.

Cache lookup is one of the functions that Juniper ATP Cloud performs to analyze and detect malware. Cache lookup is the first step in the pipeline approach that Juniper ATP Cloud uses to examine files. Cache lookup checks whether the file has been seen before and whether it has a stored verdict in the database. If the file is known to be malicious, the verdict is returned to the SRX Series Firewall and the file is dropped. If the file is not found in the cache, the analysis continues with the other techniques1.

Dynamic analysis is another function that Juniper ATP Cloud performs to analyze and detect malware. Dynamic analysis runs the file in a sandbox environment and observes its behavior and actions. Dynamic analysis can reveal the hidden or obfuscated functionality of malware, such as network connections, file modifications, registry changes, and process injections. Dynamic analysis can also detect zero-day threats and evasive malware that try to avoid static analysis1.

References:

How is Malware Analyzed and Detected? | ATP Cloud | Juniper Networks