According to AT&T's Breach Report, "The micro-blog social media site, Twitter, has informed users of an issue with their support form system which led to a minor data breach. Last month, Twitter noticed a large number of inquiries from Chinese and Saudi Arabian IP addresses, driving them to believe the attack ties to state-sponsored actors.
The intent of the breach is not known, yet the hackers were able to view Twitter user's country code of their phone numbers. Twitter has informed affected users, locked accounts which appear to be compromised, and reported the security issue is resolved.
Read More https://help.twitter.com/en/support-form
Next Steps:Twitter users should reset their passwords and make sure that their potentially compromised password is not used on any other websites., If you believe your account was affected by this breach, reach out to Twitter's data protection center.Breach occurred on November 15, 2018