Slack although has assured all its users that it has blocked the unauthorized access and to prevent such future events the company has released 2 new security features, 'Two Factor Authentication' and 'Password Kill-Switch', along with these have made changes to its technical infrastructure.
Password Kill-Switch, allows the owners of the team to instantly reset all team passwords and end all team members user sessions.This hands the team owner with a powerful last ditch security option. The company made certain with new security options and changes to the technical infrastructure, makes the Slack team just that much safer.
Slack recommended, for those unfamiliar with Two Factor Authentication to visit their help site. Already signed in users can set up 2FA here. For more help users can check out Slack's full announcement.