You should change your Slack password if you used the app on Android, according to an email sent out by the company and published by Android Police. Apparently, from December 21st to January 21st, the Android version of the Slack app would store users’ credentials in plain text, which theoretically means any other apps on your phone could have access to them.
If you’ve got the popular communications tool installed on your Android phone, the first thing you’ll want to do is update to the latest version from the Play Store since changing your password won’t do any good if you’re still running the old version. Then, if you got the email from Slack, you can click on the link to change your password. Otherwise, you’ll have to reset your password from a desktop computer using Slack’s instructions.
First, sign in to Slack, then go to your profile, which can be accessed by clicking your picture in the top right-hand corner of the app or web app and clicking View Profile. Then, click the More button and Account Settings. From there, you should be able to change your password, though it’s worth noting that the option won’t be available if your organization uses Single Sign-On.
Of course, if you used your Slack password on other websites, you should change your passwords for those, too (preferably to something unique).