Seoul , South Korea ( CNN ) -- The suspected cyberattack targeting South Korean banks and broadcasters originated from an IP address in China , South Korean regulators said Thursday , heightening suspicions of North Korean involvement . The attack Wednesday damaged 32,000 computers and servers at media and financial companies , South Korea 's Communications Commission said . It infected banks ' and broadcasters ' computer networks with a malicious program , or malware , that slowed or shut down systems , officials and the semiofficial Yonhap News Agency said . Suspicion immediately fell on North Korea , which has recently renewed threats to go to war with the South amid rising tensions over Pyongyang 's nuclear weapons , and missile testing and international efforts to stop them . Some past cyberattacks on South Korean organizations that officials linked to North Korea were traced to IP addresses in China . An IP address is the number that identifies a network or device on the Internet . China , which has been accused by U.S. organizations of supporting cyberattacks , said Thursday that it was aware of reports on the matter . `` We have pointed out many times that hacking is a global issue . It is anonymous and transnational , '' said Hong Lei , a Chinese foreign ministry spokesman . `` Hackers would often use IP addresses from other countries to launch cyberattacks . '' South Korean officials are still analyzing the cause of the network crashes and are working to prevent any further damage , the country 's communications commission said . Increased alert level . The military has stepped up its cyberdefense efforts in response to the widespread outages , which hit nine companies , Yonhap reported , citing the National Police Agency . Government computer networks did not seem to be affected , Yonhap cited the National Computing and Information Agency as saying . A joint team from government , the military and private industry was responding . A South Korean official close to the investigation told CNN that malicious computer code spread through hacking caused the outages . How the hackers got in and spread the code remains under investigation , and analysts are examining the malware , the official said . U.S. flies B-52s over South Korea . Previous attacks linked to North . South Korean officials have not said who they suspect unleashed the malicious code , but experts believe it is consistent with what North Korea has done in the past . `` It 's happened before in similar circumstances where there have been tensions on the peninsula , '' said Adam Segal , a cybersecurity expert with the Council on Foreign Relations . There did n't appear to be any mention of the computer crash in North Korean state media . South Korea has accused the North of similar hacking attacks before , including incidents in 2010 and 2012 that also targeted banks and media organizations . The North rejected the allegations . The outages come amid heightened tensions on the Korean Peninsula , with the North angrily responding to a recent U.N. Security Council vote to impose tougher sanctions on Pyongyang after the country 's latest nuclear test last month . Last week , North Korea invalidated its 60-year-old armistice with the South . It has threatened to attack its neighbor with nuclear weapons and has also threatened the United States . The armistice agreement , signed in 1953 , ended the three-year war between North and South but left the two nations technically in a state of war . The United States has deployed B-52 bombers to conduct high-profile flyovers of its South Korean ally and announced that it will deploy new ground-based missile interceptors on its West Coast against the remote possibility that North Korea could strike the United States with long-range weapons . Under threat , South Koreans mull nuclear weapons . Accusations against U.S. , South Korea . Last week , North Korea complained that it was the victim of `` intensive and persistent virus attacks '' from the United States and South Korea , according to KCNA , the official North Korean news agency . Yonhap said Wednesday 's outages affected three broadcasters , four banks and two insurance companies . The three broadcasters -- KBS , MBC and YTN -- reported varying levels of trouble containing the virus . While the networks remained on the air , cable network YTN said editing equipment had been affected and it expected to experience broadcasting problems , Yonhap reported . Computer networks stopped working entirely at three banks -- Shinhan , Nonghyup and Jeju -- around 2 p.m. Wednesday , Yonhap reported , citing the National Police Agency . Another financial institution , Woori Bank in Seoul , reported it was able to fend off a hacking attack about the same time . The banks that were affected reported problems with a variety of systems , including Internet banking , ATMs and telecommunication services , and some branches stayed open late because of the slowdown , Yonhap said . CNN 's K.J . Kwon reported from Seoul , Jethro Mullen from Hong Kong and Michael Pearson from Atlanta . Judy Kwon in Hong Kong and Dayu Zhang in Beijing contributed to this report .
NEW : China says they often use email addresses from other countries . North Korea has staged similar attacks in the past , experts says . Previous attacks linked to the North have been traced to Chinese addresses . Overall , broadcasters targeted ; social networks unaffected , expert reports .