The article mentioned that it would be computers that are used in scanning DNA that could be infected. I’ll just post what it said as to how, but I will admit it is more than I can understand, so it could be full of holes as far as I know!
So how did we write executable code into a DNA strand in the first place?
First, the researchers decided on the exploit they meant to use. It wasn’t an accident that the scientists picked C for their exploit. C has a well-known set of vulnerabilities in some functions that leave systems open to a classic buffer-overflow attack.
Then, they encoded their snippet of C in a simple cipher, using nucleobases for binary pairs: A = 00, C = 01, G = 10, T = 11.
Computers run on a binary stream of electrical impulses that alternates between OFF and ON: 0 and 1. As a consequence, executable code has to go through the binary state on some level. Reading the DNA sequence got the malicious code into the computer that was doing the read, and from there it took advantage of a buffer overflow and got loose in the system to grab for privileges.
The conversion from ASCII As, Ts, Gs, and Cs into a stream of bits is done in a fixed-size buffer that assumes a reasonable maximum read length.
Four bytes are used to make the conversion function return to the system() function in the C standard library, which executes shell commands, and four more bytes were used to tell system() where the command is in memory.