‘Black Dot’ Unicode bug can crash Messages—here’s how to fix it

Jason Cross
10 May, 2018
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Uh oh! Another Unicode attack is messing up a popular messaging platform. This time it’s Apple’s own Messages app being hit by what has come to be called the “Black Dot” bug.

We know iPhones and iPads running iOS 11.3 and 11.4 beta are affected, and it’s highly likely that Apple Watch and Apple TV are as well. Messages on the Mac might be affected as well, but the greater resources of the Mac could give you the ability to quickly delete the message thread before the app becomes totally unresponsive.

Here’s what is happening: Users can send you an iMessage (not SMS text) filled with so many invisible Unicode characters that, when your iPhone or iPad tries to read the message, it chokes on the massive amount of memory and CPUcycles required to process all of it. Messages will lock up, and while you might be able to close the app, it will crash again as soon as you re-open it and the message is displayed again.

Why it’s called the ‘Black Dot’ bug: A similar Unicode bug was recently spread in WhatsApp with the emojis <⚫️>

and a warning not to touch the black dot. If a user did, it would expand the hidden unicode and crash the app. The current iOS bug operates a bit differently, but is being spread with the same symbol. So, while neither attack technically has anything to do with the black dot emoji, they have taken on its name.

What to do if you get hit: If someone sends you the “Black Dot” message and locks up Messages on your iPhone or iPad, there are a few workarounds to regain control. They all involve the same goal—get the message off the screen so it’s not rendered when you re-open the app, and then delete the message conversation so it doesn’t crash when you scroll back and the message is displayed again. Here’s the method we suggest:

  • Force-quit the Messages app.
  • Ask Siri to send a message to the person who sent you the Black Dot. Make sure you send multiple messages or a very long message that will knock theirs off the screen.
  • 3D-Touch on Messages and select New Message, then hit Cancel in the top-right corner of the new message to get back to the conversations list.
  • Delete the conversation containing the Black Dot attack (swipe left and tap Delete).

If you have another device synced to the same iCloud account, you may be able to open Messages on it directly to the conversations list, without opening the Black Dot message, and delete the conversation from the list there.

The bug is serious, but not yet widespread; the <⚫️>

5 Comments

5 people were compelled to have their say. We encourage you to do the same..

  1. Mike Turner says:

    The title of this article implies you will tell folks how to fix the problem, but you don’t do so. You might like to re-release this online with the solution, which is actually pretty simple.

    How to fix on iPhone 6s and newer:

    Step 1: First of all, you are going to need to force close the Messages app to get back to the Home screen. Invoke Siri via the usual mechanism and give the instruction to send a text to the person who sent you the malicious message. This will ensure that the affected string of text isn’t the last message in that conversation.

    Step 2: Use the 3D Touch action on the Messages icon and select to compose a new message. Once that action happens, tap on Cancel in the top-right corner.

    Step 3: Select Edit on the conversation list. Select the circle to the left of the offending conversation and then choose the Delete option to remove the offending conversation from the messages list.

    How to fix on pre-iPhone 6s devices:

    Step 1: As above, force close the Messages app to get back to the Home screen. Invoke Siri and ask the assistant to send as many messages as possible to ensure that the string of Unicode is no longer present on the display at all when the conversation is opened.

    Step 2: Open the Messages app once again and select the Back arrow to get back to the Conversation list. Tap on Edit and then tap the circle to the left of the affected conversation.

    Step 3: Tap on Delete to remove the selected conversation.

  2. Rudolf Victora says:

    OK, the article title says, ‘Black Dot’ Unicode bug can crash Messages—here’s how to fix it. So, where is the ‘here’s how to fix it’ part?

  3. Mark Darrell says:

    What happened to the “here’s how to fix it” part of the Black Dot article?

  4. Macworld Australia Staff says:

    Oh my – it seems that the presence of certain characters caused part of the post to disappear after publishing. It should be all fixed now.

  5. Macworld Australia Staff says:

    Apologies – the content system struggled with some of the characters in the article and dropped a big piece of the content. it’s fixed now. Apologies.

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