Catalin Cimpanu reminds us in Student Expelled for Using Hardware Keylogger to Hack School, Change Grades not every effective hacking attack uses a zero-day vulnerability.
Zero-days get most of the press, ‘Zero Days’ Documentary Exposes A Looming Threat Of The Digital Age, but capturing the keystrokes on a computer keyboard, can be just as effective for stealing logins/passwords and other data.
Cimpanu suggests that hardware keyloggers can be had on Amazon or eBay for a little as $20.
I’m not sure when he looked but a search today shows the cheapest price on Amazon is $52.59 and on eBay $29.79. Check for current pricing.
I haven’t used it but the Keyllama 4MB USB Value Keylogger has an attractive form factor (1.6″) at $55.50.
USB keyloggers (there are software keyloggers) require physical access for installation and retrieval.
You can attempt to play your favorite spy character or you can identify the cleaning service used by your target. Turnover in the cleaning business runs from 75 percent to 400 percent so finding or inserting a confederate is only a matter of time.
USB keyloggers aren’t necessary at the NSA as logins/passwords are available for the asking. (Snowden)