CareFirst BlueCross BlueShield on Wednesday said it had been hit with a data breach that compromised the personal information on approximately 1.1 million customers . There are indications that the same attack methods may have been used in this intrusion as with breaches at Anthem and Premera , incidents that collectively involved data on more than 90 million Americans . On May 20 , 2015 , CareFirst BlueCross BlueShield ( CareFirst ) announced that the company has been the target of a sophisticated cyberattack . The attackers gained limited , unauthorized access to a single CareFirst database . This was discovered as a part of the company 's ongoing Information Technology ( IT ) security efforts in the wake of recent cyberattacks on health insurers . CareFirst engaged Mandiant _ _ one of the world 's leading cybersecurity firms _ _ to conduct an end - to - end examination of its IT environment . This review included multiple , comprehensive scans of the CareFirst 's IT systems for any evidence of a cyberattack . The review determined that in June 2014 cyberattackers gained access to a single database in which CareFirst stores data that members and other individuals enter to access CareFirst 's websites and online services . Mandiant completed its review and found no indication of any other prior or subsequent attack or evidence that other personal information was accessed . Evidence suggests the attackers could have potentially acquired member - created user names created by individuals to access CareFirst 's website , as well as members ' names , birth dates , email addresses and subscriber identification number . However , CareFirst user names must be used in conjunction with a member - created password to gain access to underlying member data through CareFirst 's website . The database in question did not include these passwords because they are fully encrypted and stored in a separate system as a safeguard against such attacks . The database accessed by attackers contained no member Social Security numbers , medical claims , employment , credit card , or financial information . " We deeply regret the concern this attack may cause " , said CareFirst President and CEO Chet Burrell . " We are making sure those affected understand the extent of the attack _ _ and what information was and was not affected . Even though the information in question would be of limited use to an attacker , we want to protect our members from any potential use of their information and will be offering free credit monitoring and identity theft protection for those affected for two years . " Approximately 1.1 million current and former CareFirst members and individuals who do business with CareFirst online who registered to use CareFirst 's websites prior to June 20 , 2014 are affected by this event . All affected members will receive a letter from CareFirst offering two free years of credit monitoring and identity theft protection . The letters will contain an activation code and you must have the letter to enroll in the offered protections . Out of an abundance of caution , CareFirst has blocked member access to these accounts and will request that members create new user names and passwords . ;