1. A system comprising: at least one hardware device processor; a receiver that obtains, via the at least one hardware device processor, a test object that includes dynamic executable code; a transformer that transforms at least a portion of the test object into a transformed format test object that is configured to execute in a hosted isolated computing environment, the transforming including transforming the at least a portion of the test object into a locally stored document object model (DOM) format that is configured to model at least one computer program included in the test object, the transforming including modifying Universal Resource Identifiers (URIs) to reference only items located locally to the hosted isolated computing environment; an execution engine that initiates, via the at least one hardware device processor, directed execution of the transformed format test object, in the hosted isolated computing environment; and a detector that detects dynamic code vulnerabilities of the test object, based on the directed execution.