The FBI admitted that they believe hackers broke into AT&T's syems last year to steal months of call and text logs. According to a document reviewed by Bloomberg, the FBI scrambled to contain a disaster,

A breach of AT&T that exposed “nearly all” of the company’s customers may have included records related to confidential FBI sources, potentially explaining the bureau’s new embrace of end-to-end encryption.

FBI leaders have warned that hackers who breached AT&T’s system last year likely stole months of agents’ call and text logs, prompting an urgent effort to safeguard confidential informants’ identities,