Researchers recovered 75,000 “deleted” files from old flash drives

Be careful when throwing away or giving someone an old flash drive. Even if you have deleted all the information from the media, this does not mean that it cannot be restored. This was clearly proven by cybersecurity researchers at the University of Abertay (Scotland). For the sake of the experiment, they bought a hundred used flash drives at an Internet flea market and restored 75,000 files from them that were deleted by the previous owners. The recovered files include valuable tax returns, bank statements, contract data, and other sensitive information.

Sensitive Information

Only 32 flash drives out of a hundred were cleaned correctly, with the complete removal of information. Using public data recovery tools, the researchers were able to partially recover files from 26 flash drives and entire files from the remaining 42 USB drives.

Many of the extracted files were found to be highly sensitive. They included password lists, contracts, bank statements, and tax returns. Many flash drives had private photographs embedded with the date and time of the shooting.

“This is an extremely worrying situation. The potential for malicious use of this information with extremely serious consequences is enormous. An unscrupulous buyer could use the recovered files to access seller accounts if the passwords are still valid. He might even try those passwords on other accounts given how common password reuse is. It is likely that an attacker could find the seller’s email address among the files. He could try to deduct money from bank accounts or even blackmail the seller by threatening to release any compromising information.”says Professor Karen Renaud of Abertay University’s Cybersecurity Department.

According to Professor Renault, many people don’t even realize that when computers delete files, they don’t actually destroy the information completely. “The file is removed from the media’s TOC, so it’s basically just hidden from view. They are still there. And if you know how, you can easily restore them using public tools”says the professor.

What to do?

If you are going to sell or transfer to another person a flash drive on which something confidential was previously stored, use special software for deep cleaning of the media. These programs are free and publicly available.

If you plan to just throw away the flash drive as unnecessary, then just destroy it. Burn the media or give it a good hammering to damage its silicon innards. Only in this way you are guaranteed to make it impossible for a third party to recover information.

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