Trend Micro Inc.

Yi-Hung Cheng

Chi-Huang Fan

Kun-Wei Lee

Chang-Hsing Ho

File modifications performed by malicious codes are detected by detecting a file modification for an original file before the file modification is performed on the original file. In response to detecting the file modification, a corresponding shadow file is created. The shadow file represents the original file as modified by the file modification. Before allowing the file modification to be performed on the original file, the original file is compared to the shadow file to determine if the file modification is being performed by malicious codes. The file modification may be deemed to be performed by malicious codes when the file modification involves, for example, entry point append, entry point prepend, entry point obfuscation, cavity, overwriting, or mal-tattoo.

Detection of file modifications performed by malicious codes

Upon detection of a suspicious file, a client computer sends feedback data to an anti-malware service over the Internet. Files that are not suspicious or that are known clean are not reported; files that are known malware are acted upon immediately without needing to report them to the anti-malware service. Upon detection, no alert or warning is provided to the user of the client computer. The anti-malware service correlates data from other detection engines on the client computer or from other client computers and determines whether the file is malware or not. A new virus pattern is generated if the file is malware and includes the virus signature of the file; the new virus pattern is distributed back to the client computers. If not malware, no action need be taken, or, the virus signature of the file is removed from existing pattern files.

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Taipei, Taiwan

Yi-Hung Cheng