I was having problems with my Kingston 8GB USB drive (it kept saying "write protected"). I solved the problem by first using ChipGenius and then a program called "Restore v188.8.131.52". I downloaded from a Russian website. But along with the program I obviously downloaded a virus too (Kometa virus, a docked toolbar appeared on the right of my screen). Is it possible, despite being formatted, for the USB to be infected and the firmware to be messed up?
Unfortunately, without more specific information on the infection, it's hard to know how likely it is, and it probably isn't likely* that it flashed the firmware in such a way as to infect it, but you can't be 100% sure.
* This is not to say of malware that uses the Autorun feature which hop off of a USB flash drive by using
autorun.inf. It's actually not unlikely that malware on the machine may hop onto the flash drive that way.
Why wouldn't formatting the USB stick help?
The USB essentially has 2 different storage areas, there is the one that stores your files, and the one that holds the firmware.
If the malware has infected the firmware then it would not be on the normal storage, so formatting the normal storage wouldn't help.
Why wouldn't reflashing the USB stick help?
Reflashing uses the current firmware to update the firmware, so there is no way to be sure that the old firmware hasn't just pretended to update the USB stick.
Is the USB definately infected?
It is hard to tell if the USB is definately infected, but it is also hard to tell that the USB is definately not infected, so it can no longer be treated as safe.