A follow-up report by security researchers Talal Haj Bakry and Tommy Mysk has alleged that Facebook Messenger and Instagram are collecting and using data from link previews in a way that would breach European privacy law.
In October last year, Bakry and Mysk revealed that link previews in popular messaging apps can lead to security and privacy issues on iOS and Android. It was discovered that apps could leak IP addresses, expose links sent in end-to-end encrypted chats, download large files without users' consent, and copy private data through link previews.
In that report, Bakry and Mysk found that Facebook Messenger and Instagram behaved unlike other messaging apps in that they downloaded the entire contents of any link to its servers, regardless of size. When questioned about this unusual behavior, Facebook reportedly said that it considers this to be "working as intended."
Copies of link preview data kept on external servers could be subject to breaches or misuse, which may be particularly concerning for users who send links to sensitive or confidential private data such as business documents, bills, contracts, or medical records.
Now, Bakry and Mysk have found that Facebook has recently stopped generating link previews in Messenger and Instagram for users in Europe to comply with the European Union's ePrivacy Directive. The change also applies to users outside Europe if they communicate with someone in the region.
Links sent in Facebook Messenger as seen in Europe and other regionsThe researchers suggest that since Europe has "some of the most robust privacy laws" and Facebook has now removed link previews seemingly to comply with the legislation, the company must have been using the data from link previews in a way that would breach the ePrivacy Directive.
It is an implicit confirmation that Facebook's handling of link previews in Messenger and Instagram did not conform to privacy regulations in Europe, otherwise they wouldn't have disabled the feature... Stopping this service in Europe strongly hints that Facebook may be using this content for purposes other than generating previews.
Bakry and Mysk believe that Facebook's link previews may have infringed on articles 4:1a, 4:2, and 5:3 of the ePrivacy Directive. These articles include the requirement that personal data can only be accessed by authorized personnel for legal purposes, the need to inform users of the risks of a data breach, and the need to gain user consent having been provided with "clear and comprehensive information" about how data is collected.
As links may relate to personal data, the ePrivacy Directive prevents Facebook from storing, processing, or using this information without explicit consent from users in the EU. Facebook would also have to make it clear to users why it is downloading the contents of link previews prior to requesting consent.
Bakry and Mysk have demonstrated that Facebook servers download and store the content of links sent through its apps, and if the same link is sent a second time, Facebook generates a link preview without downloading the contents of the link. This purportedly indicates that the content is stored or cached by Facebook and is proven by the amount of data that is uploaded from a user's device.
Link previews continue to be available in Messenger and Instagram for users outside Europe. Facebook's current Terms of Service state that any content users share through any of Facebook's services will be used for various purposes such as personalizing content, ads, making suggestions, and learning about users, both on and off Facebook's products. In Europe, this use of personal data now requires explicit consent from users even if it is approved by Facebook's Terms of Service.
Facebook disabled link previews for users in Europe to comply with new privacy regulations. This confirms our privacy concerns that sending links to private files in Messenger and Instagram is unsafe. While Facebook did disable link previews in Europe, users in other regions should refrain from sending links through either of these apps. The better option would be to switch to other messaging apps which respect user privacy in all parts of the world alike.
Bakry and Mysk are now actively recommending that users outside Europe do not send links in Messenger or Instagram due to privacy concerns, and have even suggested that users move to other messaging apps entirely.
Beyond link previews, the researchers have previously investigated popular iPhone and iPad apps "snooping" on iOS pasteboard data and HTTP security vulnerabilities in TikTok.
