Some users carefully protect their computers and storage media, but no one is more interested in the security of the device sold than its buyer. It is possible that not only someone else’s data, but also a bonus in the form of malware, will appear on a laptop just bought at a flea market. Antivirus detected threats on 17% of the devices examined by Prois and Funk.

Background: a larger study

Experts began checking data on used devices after a study commissioned by Kaspersky Lab conducted by Arlington Research. She interviewed several thousand buyers of used equipment in the UK, Germany and Austria and found out that the devices they purchased were a real source of data leakage. More than half of several hundred respondents found photos, explicit materials, contact and credentials, or confidential documents (for example, passport scans) on newly acquired second-hand gadgets.

Seller, be vigilant!

Only a few respondents ignored the data of the former owner on the purchased gadget, immediately deleted it, reported it to the past owner or contacted the authorities. According to 74% of respondents, they would at least look at what the former owner left. At the same time, one in ten admitted that they would sell the data they found if they could benefit from it.

Tips and recommendations

For sellers

The main task of the seller is to erase personal information from the device in order to preserve privacy and protect yourself. Of course, do not forget about the security of the device (and we hope that you took care of this while using it), but it is much more important not to leave a gift to the new owner in the form of a copy of your passport or email password.

Before deleting your data from the device you are selling (be it a phone, computer, memory card or other media), be sure to make a backup copy of it.

Remove the SIM card and memory card from the phone; delete the eSIM data if you used it.

Enable two-factor authentication for any accounts that support this feature, and then log out of all services (banking applications, email, social networks, and so on) on the device that they decided to sell.

Perform a factory reset or format the media.

Keep in mind that in many cases, data can be restored even after resetting to factory settings and formatting. Look for tips on how to delete all the information so that it cannot be restored (this is done in different ways – depending on the type of device, its model and configuration).