As soon as Alex gets the nanobot platform specifications and their source code, she begins to study them for any vulnerabilities. Dr. Anderson does the same. After several hours, Alex's computer science and professional hacking background pays off.
"Here," she says, pointing over the doctor's shoulder to a jumble of code that makes absolutely no sense to you. "You made a mistake here - that pointer references a memory location that you already defined earlier. The pointer seems to be contained in the DNA modification subroutines."
"Yes, yes, that's it!" Dr. Anderson nearly jumps out of her chair. "If we can run the DMod functions while simultaneously overwriting that memory space..."
"Which should be rather easy, given their main purpose."
"And the memory space is within a simple cellular analysis program! If we can trick the bots into executing a DNA repair by injecting foreign DNA while triggering the immune functions..."
"We can cause a buffer overflow and possibly crash the nanobots long enough to turn back!"
"Which is good for us," you say.
"In simple, nontechnical terms, yes, that's the idea." Alex smiles broadly. "The only problem is, we have no idea exactly which factors could trigger the overflow. Which means we need a test subject..."
As Alex finishes her words, four eyes are staring at Dr. Anderson. The doctor shudders. "Well," she says, "let's hurry up and get it over with."