{"id":31991,"date":"2020-01-06T11:45:45","date_gmt":"2020-01-06T16:45:45","guid":{"rendered":"https:\/\/www.kaspersky.com\/blog\/?p=31991"},"modified":"2020-05-18T07:41:07","modified_gmt":"2020-05-18T11:41:07","slug":"twitter-epilepsy-attack-aftermath","status":"publish","type":"post","link":"https:\/\/www.kaspersky.com\/blog\/twitter-epilepsy-attack-aftermath\/31991\/","title":{"rendered":"The aftermath of the Twitter epilepsy attack"},"content":{"rendered":"

November was National Epilepsy Awareness Month in the United States. Last November indeed saw a greater awareness of epilepsy, but most likely because of a scandalous attack: Internet trolls on Twitter used flashing animated images, and tagged the Epilepsy Foundation<\/a>, to harm people by causing epileptic seizures.<\/p>\n

How the attack worked<\/h2>\n

Epilepsy, a neurological disorder, is characterized by recurrent epileptic seizures. Every year more than 100,000 people die because of epilepsy. One of its common variants is photosensitive epilepsy,<\/em> in which seizures can be triggered by flickering lights, and the attack targeted people with this form of epilepsy.<\/p>\n

Twitter users can post not only short text messages, but also images, videos, and animated images as well. The latter comes in two flavors: GIF and animated PNG (APNG). The two file types are largely the same, differing mainly in image quality and color depth, but in this case, the attackers took advantage of APNGs\u2019 ability to bypass Twitter\u2019s autoplay settings.<\/p>\n

Registered Twitter users can choose if they want GIFs and videos to start playing as soon as the media appears in their feeds. Users with epilepsy may turn off autoplay specifically to avoid animated content that could trigger a seizure, but until recently the setting did not apply to APNGs, which started playing automatically no matter what.<\/p>\n

Abusing APNGs was the core idea of the troll attack. According to CNN\u2019s report, more than 30 accounts posted tweets with strobing images<\/a>, tagging the Epilepsy Foundation and copying its hashtags. The images were mostly APNGs, so they started playing \u2014 and strobing \u2014 automatically. And during national awareness month, more people than usual were following the Epilepsy Foundation account and hashtags. Quite a few likely had photosensitive epilepsy.<\/p>\n

After the attack<\/h2>\n

In the month that followed, a lot happened.<\/p>\n