Using a commercial off-the-shelf brain-computer interface, the researchers have shown that it’s possible to hack your brain. They found they were able to extract hints directly from electrical signals of the test subjects’ brains that partially revealed private information like the location of their homes, faces they recognized and even their credit card PINs. The researchers used a program that flashes up pictures of maps and banks, and makes a note every time your brain experiences a P300, a pattern that occurs when you recognize something that is meaningful.
Source: https://thehackernews.com/2012/08/sensitive-data-in-human-brain.html