Cyberattacks on high-profile companies are becoming an increasingly common occurrence. Most recently The New York Times fell victim to a specific kind of attack: Advanced Persistent Threat, or APT. 
See a timeline of some notable incidents of cyber attacks in the recent past >
APTs are unique in that the perpetrators usually have longer-term objectives. Once hackers launch an APT attack, the goal is to remain in the breached network for as long as possible, siphoning sensitive material from the company in a continual loop until being discovered and fully removed from the system.
Source: Mandiant
