Beijing hotly denies accusations of official involvement in massive cyberattacks against foreign targets, insinuating such activity is the work of rogues. However, at least one piece of evidence cited by experts points to professional cyberspies: China’s hackers do not work weekends.
Accusations of state-sanctioned hacking took center stage this past week following a detailed report by US-based Internet security firm Mandiant. It added to growing suspicion that the Chinese military is not only stealing national defense secrets and harassing dissidents, but also pilfering information from foreign companies that could be worth millions or even billions of US dollars.
Experts say Chinese hacking attacks are characterized not only by their brazenness, but by their persistence.
“China conducts at least an order of magnitude more than the next country,” said Martin Libicki, a specialist on cyberwarfare at the Rand Corp, based in Santa Monica, California.
The fact that hackers take weekends off suggests they are paid, and that would belie “the notion that the hackers are private,” he said.
Libicki and other cyberwarfare experts have long noted a Monday-through-Friday pattern in the intensity of attacks believed to come from Chinese sources, though there has been little evidence released publicly directly linking the Chinese military to the attacks.
Mandiant went a step further in its report on Tuesday saying that it had traced hacking activities against 141 foreign entities in the US, Canada, Britain and elsewhere to a group of operators known as the “Comment Crew” or “APT1,” for “Advanced Persistent Threat 1,” which it traced back to the People’s Liberation Army (PLA) Unit 61398. The unit is headquartered in a nondescript 12-story building inside a military compound in a crowded suburb of China’s financial hub of Shanghai.
Attackers stole information about pricing, contract negotiations, manufacturing, product testing and corporate acquisitions, the company said.
Hacker teams regularly began work, for the most part, at 8am Beijing time. Usually they continued for a standard work day, but sometimes the hacking persisted until midnight. Occasionally, the attacks stopped for two-week periods, Mandiant said, though the reason was not clear.
China denies any official involvement, calling such accusations “groundless” and insisting that Beijing is itself a major victim of hacking attacks, the largest number of which originate in the US.
While not denying hacking attacks originated in China, Chinese Ministry of Foreign Affairs spokesman Hong Lei (洪磊) said on Thursday that it was flat out wrong to accuse the Chinese government or military of being behind them.
Mandiant and other experts believe Unit 61398 to be a branch of the PLA General Staff’s Third Department responsible for collection and analysis of electronic signals such as e-mails and phone calls. It and the Fourth Department, responsible for electronic warfare, are believed to be the PLA units mainly responsible for infiltrating and manipulating computer networks.
China acknowledges pursuing these strategies as a key to delivering an initial blow to an opponent’s communications and other infrastructure during wartime — but the techniques are often the same as those used to steal information for commercial use.