F5's Andrew Shalnev said in a blog post that the campaign in question targeted Windows IIS 6.0 servers through the CVE-2017-7269 released more than one year ago.
The malware in question was named lsass.eXe, presumably in order that it would be confused with the legitimate lsass.exe process. Additionally, the binary was proxy aware and used TLS encryption.
Shalnev said practically all the attacks were coming from the US and China, with the malware hosting server located in Beijing within China's Unicom's network.
Shalnev pointed out that IIS 6.0 was mainly a part of Windows Server 2003, though not exclusive to this operating system.
"At the time the vulnerability was released, Microsoft announced that the bug wouldn’t be fixed since the OS was EOL (end-of-life)," he explained. "Soon after Microsoft published a patch addressing the issue as there were still many servers running that OS, and exploit campaigns were active."
He said that once the malware downloaded the cryptocurrency mining script, it was instructed to mine to several pools to this wallet: etnjzC1mw32gSBsjuYgwWKH5fZH6ca45MDxi6UwQQ9C8GJErY3rVrqJA8sDtPKMJXsPuv4vdSyDzGVTVqgAh97GT8smQMoUaQn.
But the campaign had not managed to make much money, he noted, pointing out that at the time of his writing the blog post, the attacker had earned about US$99.
"This is a very small amount of money earned, given how lucrative most other crypto-mining campaigns are currently, making this campaign appear unsuccessful," Shalnev said.
"One theory is that the attacker will change the wallet address from time to time. Another theory is that there aren’t many IIS 6.0 servers available to exploit left."