U.S. Banks Hit with Biggest Cyberattacks Ever

By Trey Thoelcke Published Sep 28, 7:12AM EDT

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Security experts say the recent “denial of service” cyberattacks on big U.S. banks were the largest ever recorded by a wide margin. Since Sept. 19, the banking websites of Bank of America Corp. (NYSE: BAC), J.P. Morgan Chase & Co. (NYSE: JPM), Wells Fargo & Co. (NYSE: WFC), U.S. Bancorp. (NYSE: USB) and PNC Financial Services Group Inc. (NYSE: PNC) have all suffered day-long slowdowns and been at times unreachable for many customers.

It is not unusual for banks to get hit by cyberattackers and they have some of the best defenses against them. But this time the volume of traffic sent to these sites in order make then crash was unprecedented — 10 to 20 times the volume that normally seen.

Senator Joe Lieberman said in a C-SPAN interview on Wednesday that he believed the attacks were launched by Iran in response to the increasingly strong economic sanctions that the United States and its allies have put on Iranian financial institutions.

Denial of service attacks do not involve any actual hacking. No data was stolen from the banks, and their transactional systems — like their ATM networks — were unaffected. The aim of the attacks was simply to temporarily disrupt the banks’ public-facing websites. Experts warn that more such attacks may still be coming.

About the Author Trey Thoelcke →

Trey has been an editor and author at 24/7 Wall St. for more than a decade, where he has published thousands of articles analyzing corporate earnings, dividend stocks, short interest, insider buying, private equity, and market trends. His comprehensive coverage spans the full spectrum of financial markets, from blue-chip stalwarts to emerging growth companies.

Beyond 24/7 Wall St., Trey has created and edited financial content for Benzinga and AOL's BloggingStocks, contributing additional hundreds of articles to the investment community. He previously oversaw the 24/7 Climate Insights site, managing editorial operations and content strategy, and currently oversees and creates content for My Investing News.

Trey's editorial expertise extends across multiple publishing environments. He served as production editor at Dearborn Financial Publishing and development editor at Kaplan, where he helped shape financial education materials. Earlier in his career, he worked as a writer-producer at SVE. His freelance editing portfolio includes work for prestigious clients such as Sage Publications, Rand McNally, the Institute for Supply Management, the American Library Association, Eggplant Literary Productions, and Spiegel.

Outside of financial journalism, Trey writes fiction and has been an active member of the writing community for years, overseeing a long-running critique group and moderating workshop sessions at regional conventions. He lives with his family in an old house in the Midwest.