Seoul , South Korea ( CNN ) -- The suspected cyberattack that appeared to target South Korean banks and broadcasters Wednesday originated from an IP address in China , South Korea 's Communications Committee said in a statement Thursday . The attack damaged 32,000 computers and servers of media and financial companies , the committee said . South Korean officials are analyzing the cause and are working to prevent any further damage , the committee said . The attack infected banks ' and broadcasters ' computer networks with a malicious program that slowed or shut systems down , 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 . South Korea 's military 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 presidential spokeswoman said , according to Yonhap . 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 . Wednesday 's attack is consistent with what North Korea has done in the past , said Adam Segal , a cybersecurity expert with the Council on Foreign Relations . `` It 's happened before in similar circumstances where there have been tensions on the peninsula , '' Segal said . 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 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 saber-rattling prompted the United States to deploy B-52 bombers to conduct high-profile flyovers of its South Korean ally and announce that it would 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 . 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 reported from Hong Kong and Michael Pearson wrote from Atlanta . Judy Kwon and Hilary Whiteman in Hong Kong contributed to this report .
NEW : Attack traced to IP addresses in China , officials say . North Korea has staged similar attacks in the past , expert says . Military , broadcasters safe ; government , unaffected , Yonhap reports . South Korean military steps up its cyberdefense efforts in China .