One of the common ways to hack a computer is to mess with its input data. That is, if you can feed the computer data that it interprets -- or misinterprets -- in a particular way, you can trick the computer into doing things that it wasn't intended to do. This is basically what a buffer overflow attack is: the data input overflows a buffer and ends up being executed by the computer process.
Well, some researchers did this with a computer that processes DNA, and they encoded their malware in the DNA strands themselves:
> To make the malware, the team translated a simple computer command into a short stretch of 176 DNA letters, denoted as A, G, C, and T. After ordering copies of the DNA from a vendor for $89, they fed the strands to a sequencing machine, which read off the gene letters, storing them as binary digits, 0s and 1s. > > Erlich says the attack took advantage of a spill-over effect, when data that exceeds a storage buffer can be interpreted as a computer command. In this case, the command contacted a server controlled by Kohno's team, from which they took control of a computer in their lab they were using to analyze the DNA file.