Security firm Sophos studied 50 USB flash drives bought at a major transit authority's lost property auction and found that two-thirds were infected with malware. What's more, examination of the drives uncovered information about many of the former owners of the devices, including their family, friends and colleagues.

The drives were all lost on RailCorp trains in Australia.

Here's a breakdown of the malware:

While no Mac OS X malware was discovered, nine of the USB flash drives had been used extensively by Mac owners, and seven of these drives were infected with malware.

The flash drives didn't just contain malware - they contained data files. 4,443 in fact, broken down as follows:

Files discovered included:

Lists of tax deductions.

Minutes of an activists' meeting.

School and University assignments.

AutoCAD drawings of work projects.

Photo albums of family and friends.

A CV and job application.

Software and web source code.

None of the drives examined were encrypted in any way.

The takeaway from this: