Consumers who have resold or donated their old smartphones might not want to hear this, but Android's default setting doesn't always delete your personal information, according to a new security study.
Software maker Avast recently bought 20 Android smartphones off eBay and attempted to retrieve their data, CNET reported.
"Although at first glance the phones appeared thoroughly erased, we quickly retrieved a lot of private data. In most cases, we got to the low-level analysis, which helped us recover SMS and chat messages," Avast researchers Jaromir Horejsi and David Fiser wrote in the report.
According to a blog post, Avast's discoveries included 40,000 photos, at least 250 of which were nude selfies; 750 emails and text messages; 250 contacts; the identities of four phones' previous owners; and a completed loan application. The researchers used "fairly generic, publicly available" digital forensics software that can be purchased off the shelf.
People thought they deleted information that actually remained on the smartphone's drive, the Avast report said.
"Users thought they were doing a clean wipe and factory reinstall," Avast mobile division president Jude McColgan told CNET. The problem is that doing a factory reset takes care of data "only at the application layer."
Avast sells data-wiping software as part of its Android security app that is purportedly much more effective at erasing valuable personal information from devices.
Smartphones were recently recognized as a privacy threshold by the Supreme Court, which ruled last month that authorities must obtain a search warrant before rummaging through someone's device.
"We have a very unique relationship with our mobile phones that we've never had to any other technological device," Bronson James, a lawyer who worked on one of the cell phone cases recently decided by the Supreme Court, told CNET's Ben Fox Rubin. "In our brief we equated our mobile devices as the entryway into our virtual home."
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