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Federal investigators have cracked down on one of the world's largest botnets, CBS News reported Wednesday.

The botnet, known as the 911 S5 Botnet, was implicated in generating tens of thousands of fraudulent transactions and costing victims billions of dollars, according to CBS News. The botnet's administrator, Chinese national YunHe Wang, was arrested and faces charges of leading a sophisticated cybercrime operation that impacted over 190 countries. The FBI has revealed the 911 S5 Botnet used 19 million compromised IP addresses as a conduit for a myriad of crimes including financial fraud, identity theft and child exploitation.
Wang allegedly profited substantially from this operation, purchasing luxury properties and items worldwide, totaling over $34 million. He was arrested last Friday and is charged with conspiracy and computer fraud among other counts, the outlet reported. Court documents detail how Wang sold Virtual Private Network (VPN) programs that, once downloaded, installed malware on users' computers. This malware enabled the stealthy co-opting of IP addresses, which were then sold to cybercriminals, allowing them to evade detection by masking their activities under the victims' IP addresses.

This botnet was particularly harmful as it facilitated over $5.9 billion in potential pandemic relief fraud losses, exploiting the U.S. federal lending programs intended to aid those affected by the COVID-19 pandemic.

FBI cyber division deputy assistant director Brett Leatherman said:
"The majority of the fraud came from fraudulent pandemic relief fund applications. That is a significant theft against Americans who in very difficult times were looking for financial relief related to the pandemic."
The FBI, in collaboration with international law enforcement partners, seized 23 domains and over 70 servers, significantly disrupting the botnet's operations. Authorities from Singapore and Thailand played critical roles in Wang's arrest, with ongoing efforts to extradite him to the U.S., the outlet reported. FBI Director Christopher Wray emphasized the scale of the operation, describing it as potentially the largest botnet ever dismantled.
"Working with our international partners, the FBI conducted a joint, sequenced cyber operation to dismantle the 911 S5 Botnet — likely the world's largest botnet ever."