An anonymous reader quotes a report from Ars Technica: Link previews are a ubiquitous feature found in just about every chat and messaging app, and with good reason. They make online conversations easier by providing images and text associated with the file that's being linked. Unfortunately, they can also leak our sensitive data, consume our limited bandwidth, drain our batteries, and, in one case, expose links in chats that are supposed to be end-to-end encrypted. Among the worst offenders, according to research published on Monday, were messengers from Facebook, Instagram, LinkedIn, and Line. More about that shortly.
LinkedIn performed only slightly better. Its only difference was that, rather than copying files of any size, it copied only the first 50 megabytes. Haj Bakry and Mysk reported their findings to Facebook, and the company said that both apps work as intended. Meanwhile, when the Line app opens an encrypted message and finds a link, it appears to send the link to the Line server to generate a preview. "We believe that this defeats the purpose of end-to-end encryption, since LINE servers know all about the links that are being sent through the app, and who's sharing which links to whom," Haj Bakry and Mysk wrote. Discord, Google Hangouts, Slack, Twitter, and Zoom also copy files, but they cap the amount of data at anywhere from 15MB to 50MB. [This chart] provides a comparison of each app in the study.
Read more of this story at Slashdot.