South Korea Bank Attack Is a Warning to U.S. Bankers

Hackers paralyzed two of South Korea's biggest banks for hours on Wednesday, highlighting a threat to financial networks from electronic intrusions.

Online banking, ATMs and internal systems at both Shinhan Bank, a major lender based in Seoul, shut down for roughly two hours, according to news reports. Similar systems at Nonghyup Bank, another big lender, also stopped, according to the country's Yonhap News Agency.

Both banks said their systems later came back online and that customer accounts remained uncompromised, according to news reports.

The stoppage also brought down websites at the Korean Broadcasting System, the Munhwa Broadcasting Corporation and the YTN News Channel. "The computer network has been paralyzed since 2 p.m. and we cannot do any business," a Korean Broadcasting System official told the news agency.

Malicious software was responsible for the system failure, the BBC reported, quoting an official close to the investigation. The news service reported that some computer screens at the victim networks displayed images of skulls, according to Korea's Internet Security Agency,

The attacks follow a wave of cyberattacks on the biggest U.S. banks and a series of warnings about the threat that cyber intrusions post to financial networks and other critical infrastructure.

According to some experts, Wednesday's attacks on Shinhan Bank and Nonghyup Bank forewarn financial institutions worldwide of the perils such pervasive attacks can present.

"The issue with the South Korean bank hack that should really grab everyone's attention is that complete bank networks were infected, which resulted in outages of online banking portals, ATMs, and internal bank systems," Al Pascual, a senior security analyst at Javelin Strategy & Research, which advises financial institutions on risk, said in an email.

According to Pascual, a similar attack on U.S. banks "would have a deleterious effect on consumer confidence as it would limit customer access to account functions online, while also keeping them from withdrawing their funds as cash."

The outages prompted President Park Geun Hye to order a probe whether the attacks originated in North Korea, which has previously denied charges the country sponsors cyberattacks on South Korea. U.S. officials have warned recently that a growing wave of cyberattacks have the potential to disrupt financial networks and other critical infrastructure.