Exxon Mobil, the largest U.S. oil company, and Royal Dutch Shell, the largest European oil company, are among the Western oil giants targeted in a series of cyber attacks by Chinese hackers that occurred over the past three years. Four other Western oil firms were also hit in the attacks.
Other companies impacted by the attacks include BP (BP), Europe's second-largest oil company, ConocoPhillips (COP), the third-largest U.S. oil company, Marathon Oil (MRO) and oil services firm Baker Hughes (BHI).
None of the companies disclosed they were attacked in filings with the SEC. Texas-based Baker Hughes did confirm it was attacked, but opted not to disclose the attack because it was not material to investors. In some of the cases, hackers had undetected access to company networks for more than a year, according to Bloomberg News.
Technology experts say the attacks appear to be attempts at corporate espionage. Both Exxon (XOM) and Shell (RDS-A) declined to comment on the attacks.