LOS ANGELES — The FBI and its European partners infiltrated and seized control of a major global malware network used for more than 15 years to commit a gamut of online crimes including crippling ransomware attacks, U.S. officials said Tuesday.

They then remotely removed the malicious software agent – known as Qakbot – from thousands of infected computers.

Cybersecurity experts said they were impressed by the deft dismantling of the network but cautioned that any setback to cybercrime would likely be temporary.

“Nearly ever sector of the economy has been victimized by Qakbot,” Martin Estrada, the U.S. attorney in Los Angeles, said Tuesday in announcing the takedown.

He said the criminal network had facilitated about 40 ransomware attacks alone over 18 months that investigators said netted Qakbot administrators about $58 million.

Qakbot’s ransomware victims included an Illinois-based engineering firm, financial services organizations in Alabama and Kansas, along with a Maryland defense manufacturer and a Southern California food distribution company, Estrada said.

Officials said $8.6 million in cybercurrency was seized or frozen but no arrests were announced.

Estrada said the investigation is ongoing. He would not say where administrators of the malware, which marshaled infected machines into a botnet of zombie computers, were located. Cybersecurity researchers say they are believed to be in Russia and/or other former Soviet states.

Officials estimated the so-called malware loader, a digital Swiss knife for cybercrooks also known as Pinkslipbot and Qbot, was leveraged to cause hundreds of millions of dollars in damage since first appearing in 2008 as an information-stealing bank trojan. They said millions of people in nearly every country in the world have been affected.

Typically delivered via phishing email infections, Qakbot gave criminal hackers initial access to violated computers. They could then deploy additional payloads including ransomware, steal sensitive information or gather intelligence on victims to facilitate financial fraud and crimes such as tech support and romance scams.

The Qakbot network was “literally feeding the global cybercrime supply chain,” said Donald Alway,…