Gray market services like bulletproof hosts have been popular among cybercriminals for maintaining web infrastructure anonymously.
Law enforcement crackdowns on bulletproof hosts have pushed cybercriminals towards using residential proxy services to hide malicious traffic.
Some service providers are now offering purpose-built VPNs and proxies to rotate and mask customer IP addresses, making it difficult to distinguish between legitimate and malicious traffic.
While the technology of using proxies is not new, the shift towards using them by cybercriminals has been significant in the last couple of years.