Three users of the Facebook Messenger app sued Facebook on Tuesday, saying the social network violated their privacy by collecting logs of their phone calls and text messages, in the latest legal challenge facing the company.

The U.S. lawsuit filed in federal court in the Northern District of California seeks status as a class action on behalf of all affected users and asks for unspecified damages.

And, it could be the first of many.

Facebook, which is reeling from a scandal over its handling of personal data, on Sunday acknowledged that it had been logging some users' call and text history but said it had done so only when users of the Android operating system had opted in.

Three users of the Facebook Messenger app sued Facebook on Tuesday, saying the social network violated their privacy by collecting logs of their phone calls and text messages, in the latest legal challenge facing the company. File photo

A Facebook representative could not immediately be reached for comment.

Facebook said on Sunday that it does not collect the content of calls or text messages, and that information is securely stored.

The data is not sold to third parties, it said.

The plaintiffs argue that prior to this Android update, Facebook 'exploited a vulnerability' in the permissions settings for Messenger and Facebook Lite.

It alleges that Facebook scraped 'years worth' of call and text data, including whether it was 'incoming', 'outgoing' or 'missed', as well as the date and time of each call, the number dialed, the individual called, and the duration of each call.

Android is owned by Alphabet Inc's Google, which is not named as a defendant in the suit.

However, the Google-owned mobile software firm has also attracted criticism for how its lenient app permissions rules may have allowed Facebook Messenger and other apps to collect users' personal data.

iPhone owners weren't subject to having their phone calls and texts logged by Facebook's apps because Apple has tighter security restrictions.

Many Android apps would request access to a user's address book to upload contact information, without telling them that that also meant recording call logs and text messages.

HOW DID FACEBOOK COLLECT CALL TEXT HISTORY - AND WHY WAS ONLY ANDROID AFFECTED? Facebook is currently at the center of a widespread privacy scandal that has revealed just how vulnerable users' online data is to exploitation. But it may not be the only Silicon Valley giant that's guilty of mismanaging user data. Experts now say Google may be at fault, too. In a blog post earlier this week, Facebook admitted it collects call logs and messaging histories from some Android users who installed its Messenger app or Facebook Lite, a stripped-down version of its core app. Users had to opt in to the feature in order for the information to be collected. The controversial data collection only affected Android users, not iPhone owners. Experts are concerned that Facebook may not be the only platform that's liberally collecting personal user data and making it available for third-party apps iPhone owners weren't subject to having their phone calls and texts logged by Facebook's apps because Apple has tighter security restrictions. Many users accepted the Messenger's request to merge their contact list into the app. Facebook says they offer this feature in order to make it easier to stay in touch with your contacts, without having to add each person individually. But what many users didn't realize was that when they agreed to merge their contact list, it also allowed the app to collect call logs and text messages. Once users opted in, they could also opt out by changing their app's settings. Facebook maintained that it doesn't sell the data, which includes phone contacts and text history, or collect the content of your data. Advertisement

In 2012, Android began requiring app developers to disclose that providing contact information would also entail collecting call log and messaging data.

That said, many of these apps required users to agree to those permissions because rejecting access meant the apps wouldn't work.

It was until 2015, when Android released version 6.0, or 'Marshmallow', that the firm split up those permissions categories.

Android apps may request access to a user's address book to upload contact information, without telling them that that also meant recording call logs and text messages

That meant users could agree to share contacts but reject access to call logs and messages.

Facebook started collecting that information during the same year.

While Android did take steps to strengthen its app permissions in the latest version of Android, it still doesn't seem to have resolved the issue.

That's because most Android users aren't using the latest version of the software.

When Apple releases a new version of its mobile operating system, the iOS update gets pushed out to all devices automatically because the firm owns both the software and hardware.

By comparison, Google can't do this because not all Android devices are manufactured by the company.

Questions still remain as to why Google didn't require app developers to disclose they were collecting call logs and messages in the first place.

The answer seems to be that Google, like Facebook, can attribute much of its value to the massive treasure trove of user data it oversees.

Also like Facebook, Google uses its vast collection of user data to serve up advertisements tailored to users' interests.