Major publishing firm Macmillan had its network and offices shut down following a possible ransomware attack over the past weekend, reports BleepingComputer. Macmillan said in corporate emails that some files on its network had been encrypted as a result of the attack, according to Publishers Weekly, which first broke the news regarding the security incident. The attack has also prompted the publisher's editors to lose system, email, and file access. "In case you havent heard, Macmillan is experiencing a digital security incident, and our systems are shut down out of an abundance of caution. Our offices are closed today and possibly tomorrow. We cannot access email or files. Hopefully we'll be up and running again very soon!" said Grace Kendall, an editor at Macmillan, in a tweet. Systems recovery is underway but the perpetrators of the attack remain uncertain. An investigation is still needed to determine whether attackers were able to steal data from the publishing firm.