More than two-thirds of second-hand USBs purchased from auction platforms such as eBay contain private and sensitive information belonging to their previous owners, according to researchers at Abertay University.

An analysis of 100 USB drives purchased from the e-commerce website revealed 75,000 files with personal and financial information, catalogued in three categories:

• Low sensitivity such as evidence of downloaded videos, Operating System Boot/Installation Drives (Microsoft Windows), student work, and promotional and press release materials.
• Medium sensitivity such as image files with GPS location, personal photographs and studies containing clinical trials.
• High sensitivity such as files with passwords, CVs, personal statements, employment contracts, time sheets, invoice records, divorce information, bank statements, health records and web pages.

A closer examination found that resellers properly wiped only 32 of the 100 USB devices. Using publicly available recovery tools, researchers partially recovered files from 26 of the portable storage devices and fully recovered the entire sets of files stored on the remaining 42 USBs.

This is extremely concerning, and the potential for this information to be misused with extremely serious consequences is enormous, An unscrupulous buyer could feasibly use recovered files to access sellers' accounts if the passwords are still valid, or even try the passwords on the person’s other accounts given that password re-use is so widespread.

Researchers also surveyed eBay sellers, revealing that 64% of respondents had found a used USB lying around, while 81% said they had never misplaced a USB drive.

When asked what they would do if they found a used USB, 94% of respondents said they would plug it in, 10% would format it, 38% would use forensics tools to check it out, and 44% would scan it with antivirus tools. Investigators recommend using a security solution when plugging in a previously owned USB and securely wiping drives before selling them to prevent access to any personal data.

This research was undertaken as part of my studies at Abertay University, where I graduated with a Master of Science with Merit in Ethical Hacking and Cyber Security. A full copy of this paper can be found here.