Modern ones look for the small chunk of code necessary to decrypt the virus, which is harder to tinker with.

ECONOMIST: Computer viruses: A thing of threads and patches | The

In a blog item published on Friday, Zambrini unearthed a chunk of code from the latest iTunes that he says outs Qualcomm and the next baseband provider for Apple products.

FORBES: Apple Hacker Finds Evidence Of Qualcomm In iTunes Core

For example, once the code-morphing software has translated a particular chunk of x86 code into micro-ops it can store the translated chunk in a special memory to avoid having to translate it again.

ECONOMIST: Transmetamorphosis

If it transfers a chunk of numbers to another area code, as it did with the Bronx, the new 646 code would not be needed, but the scheme would not create much extra space on the network.

ECONOMIST: The sexiest code on earth