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I recently attached two usb-sticks of colleagues to my laptop and transferred a file from one to the other. The file was sensitive and was not supposed to be copied to my PC.

Never mind the background that led to this situation - suffice to say, my laptop was available for the transfer.

Question: did the act of transferring the file from one USB port to the other via my laptop leave any local "residue"? Or can my Laptop in such a case be considered the same as a network cable?

Here some related questions:

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up vote 13 down vote accepted

USB devices talk to the computer, not to each other. During the file copy, all the data went through the RAM of the laptop -- and, precisely, through both the OS kernel and the RAM of the file explorer application. The file explorer should not have written a copy of that data anywhere on the laptop disk. However, a copy of the data has been kept in RAM by the kernel as part of the generic disk caching mechanism, and some of it may have been written to disk if the laptop was put in hibernation mode afterwards.

Of course, if the laptop was already compromised (with some malware) at the time of the copy, then your data is toast.

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Thanks. I like how you always add a little bit extra to your answers, helps me learn a lot. – Rafael Cichocki Mar 12 '13 at 16:48

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