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Messages service Signal's 'self-deleting' messages are not being deleted from your Mac OS and here’s why you care

Messaging is quite a natural task nowadays. It’s easy, it’s fun and it can allow you to communicate a greater bulk of data in a more organized and breach-free manner. From Messenger, to Viber and WhatsApp however, there is plethora of messaging apps out there, each one with its own unique extra features.

Then, there is a messages service app – right there at the top of the encrypted, top-notch security-oriented kind – which allows users to send messages that are programmed to delete themselves hence leaving no trace whatsoever; neither the content nor the information of the sender or the receiver is saves. It’s called Signal, and it’s generally considered by cyber security experts as the number one options for protecting your messages and calls from online snoops. However, it was recently discovered that it’s not working as programmed for Macintosh operating systems.

The incident was first noticed on Tuesday by security researcher Alec Muffett who took it to Twitter to inform the Signal community about the flaw. Alec twitted

“#HEADSUP: #Security Issue in #Signal. If you are using the @signalapp desktop app for Mac, check your notifications bar; messages get copied there and they seem to persist — even if they are "disappearing" messages which have been deleted/expunged from the app”

Here's what’s going on. All messages that come through from Signal to a Mac OS device but are not opened instantly, go to the notification center. The catch is, that the notification stays there even after the message itself is expected to be deleted. Those notifications are created when the app is running on the background and they include a preview of the content that has been received and the sender’s information.

What’s worse – as Alec found out – is that it’s not just the notifications that stay on your screen. Patrick Wardle, founder and chief research officer at ‘Digita Security’ inspected the bug a bit further and found out that the issue stems from the way that Signal and Macintosh work together as well as the way that macOS handles and stores notifications.

Specifically, Apple’s operating system does not delete notifications, but rather the notification banners. As Patrick put it: “[…]anything that gets displayed as a notification in the macOS Notification Center, is recorded by the OS. If the application wants the item to be removed from the Notification Center, it must ensure that the alert is dismissed by the user or programmatically!” If you want to get an insight on the code behind this bug, check out Wardle’s blog post.

In other words, it’s not a certainty, but the same bug could occur with every notification coming from virtually any app on your macOS.

Thankfully, the fix for this one is quite All you have to do is open the Signal app, go to the notification section and choose ‘Neither name nor message’ or ‘Only sender name’. This will ensure that when you get a notification on your Mac from Signal, it won’t display the sender’s information or a preview of the message.

At this point it’s worth mentioning that Apple has refused to make any comments on the matter, concerning the way that they have programmed their operating system. Stay tuned to find out all the latest news right here!

Published : May 24 2018
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