News Corp. — which owns the publishers of The Wall Street Journal and the New York Post — announced the discovery of a "persistent cyberattack" targeting a limited number of employees. An official with a cybersecurity firm working with the mass media conglomerate said the attack has links to China. The company, the publishing arm originally founded as part of the Murdoch family's media empire, disclosed the breach Friday in a financial filing to the Securities and Exchange Commission as well as through an internal email to employees. According to News Corp., the digital attack was discovered in January, at…