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US 2003/0159090 A1Published application
Method of detecting malicious code
AssigneeMarconi UK Intellectual Property Ltd.
InventorsStuart C Wray, Icarus W J Sparry
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AssigneeMarconi UK Intellectual Property Ltd.
InventorsStuart C Wray, Icarus W J Sparry
Estimating the term…
The invention provides a method of detecting malicious code in a code-executing device (10), the method characterised in that it includes the steps of: (a) generating test data which is substantially unsusceptible to compression without reducing its information content and storing it as image data (230) in memory external to the device (10); (b) loading the test data (R0 to Rm) into memory (30) of the device (10); (c) performing a checksum calculation on the test data (R0 to Rm) stored in the memory (30) of the device (10) to generate a first checksum value, performing a corresponding checksum calculation on the image data (230) to generate a second checksum value, and the comparing the first value with the second value to determine whether or not the test data in the memory of the device (30) has been corrupted; (d) repeating step (c) until sufficient test data in the memory (30) of the device (10) is checksum tested to determine whether or not malicious code is present in the device (10). The method makes it difficult for the malicious code to conceal itself from the checksums, hence it is possible to determine whether or not the device (10) has been compromised.
A method of detecting malicious code in a code-executing device, the method characterised in that it includes the steps of:
A method according to any preceding claim wherein checksum calculations performed in step (c) are performed on one or more sequences of memory locations of the memory of the device using challenges to specify the memory locations and to specify one or more initialization vectors to be used in the checksum calculations.
A method according to any preceding claim wherein at least one checksum calculation in step (c) is performed on interfacing software residing in the memory of the device, the interfacing software operable to communicate the test data to the memory of the device and to output data from the memory of the device, the interfacing software also being included in the image data for comparison.
A method according to any preceding claim wherein the rapidity with which the device outputs checksum calculations is used to determine whether or not the memory of the device includes malicious code.
A method according to any preceding claim wherein the device is hindered from accessing memory external thereto during calculation of the checksums in step (c).
A method according to any preceding claim wherein a cryptographic hash algorithm is used for calculating the checksums.
A testing apparatus operable to apply a method according to any preceding claim to interrogate a code-executing device to determine whether or not the device includes malicious code.
Dependencies are inferred from the claim text.