Patent ID: 7131036

Claim:
A method of detecting malicious code in a code-executing device, the method comprising the steps of: a) generating test data, which is substantially unsusceptible to compression without reducing its information content, and storing the test data as image data in memory external to the device; b) storing the test data into memory of the device; c) performing a checksum calculation on the test data stored in the memory of the device to generate a first checksum value, performing a corresponding checksum calculation on the image data to generate a second checksum value, and then comparing the first value with the second value to determine whether the test data stored in the memory of the device has been corrupted; d) hindering the device from accessing memory external thereto during calculation of the checksums; and e) repeating step c) until sufficient test data stored in the memory of the device is checksum tested to determine whether malicious code is present in the device.