US Patent 7814544 API-profile guided unpacking

An executable program including packed code is launched in an API-monitored environment, such as a sandboxed environment, in which each call to an API issued by the executable program is intercepted. A packer API profile list including one or more packer API profiles identifying associated sets of one or more APIs utilized by an associated known packer to unpack packed code is accessed. The executable program is allowed to run so long as the executable program issues calls to APIs within an API set of a packer API profile in the packer API profile list. When the executable program issues a call to an API not within an API set of a packer API profile in said packer API profile list, the packed code is assumed to be unpacked in memory as a memory image. The memory image is evaluated, e.g., scanned, for malicious code, and upon detection of malicious code, protective action is taken.