Article detailing the methods by which malware can obfuscate itself to avoid detection.
Obfuscation
Google dictionary says:
Malware does not want to be seen. It will hide on your computer and for the most, attempt to blend into your system. The malware may disguise itself as a legitimate file or process examples of which are making changes to the following:
• Name
• Dates and times
• Size
• Location
• Association
Malware may also try to obfuscate itself when running in memory. It may change its name to what appears to be a legitimate process name or actually hide itself within a genuine process, a technique known as hooking.