The U.S., Russia, and Canada accounted for most of the vulnerable Exim servers, which are on versions 4.97.1 or earlier, according to a report from Censys.
Organizations affected by the breach have been urged by security researcher and former Microsoft employee Kevin Beaumont to be vigilant of the emails, which were not sent in adherence to the Microsoft 365 breach process.
Officials at the City of Philadelphia have confirmed that 35,881 individuals had their personal and protected health information exfiltrated following the compromise of several email accounts from late May to late July 2023.
Aside from alerting users regarding the phishing scheme, Ethereum also disclosed performing selective email service migration and other measures to curb similar attacks in the future.
Attackers were able to obtain Authy customers' phone numbers and other data via an unauthenticated endpoint, which has since been secured, but there has been no indication of breaches of Twilio's systems and sensitive data.