US Patent 9444831 Malicious script detection using context-dependent script emulation

One embodiment relates to a computer-implemented process for detecting malicious scripts at a client computer using a malicious script detector. A web page interceptor intercepts an access of web page data at a universal resource locator address. A script preprocessor determines script fragments embedded in the web page data and extracts variable and function names from the script fragments. A context analyzer determines whether the script fragments reference known-good scripts. The context analyzer may check variable and function names in the script fragment against a database of known-good contexts. Those script fragments which were determined to reference known-good scripts may be categorized as non-malicious. An emulator may perform emulation on remaining script fragments which were not determined to reference known-good scripts and not perform emulation on the script fragments which were determined to reference known-good scripts. Other embodiments, aspects and features are also disclosed.