CopperStealer malware infected up to 5,000 hosts per day over first three months of 2021

Researchers disrupted a newly documented Chinese-based malware called CopperStealer that, since significant countermeasures started in late January, infected up to 5,000 individual hosts per day, stealing credentials of users on major platforms including Facebook, Instagram, Apple, Amazon, Bing, Google, PayPal, Tumblr and Twitter.

Sherrod DeGrippo, senior director of threat research at Proofpoint, said they were first notified of the CopperStealer malware by Twitter user TheAnalyst. She said CopperStealer, which Proofpoint fully describes in a blog post, exhibits many of the same targeting and delivery methods as SilentFade, a Chinese-sourced malware family first reported by Facebook in 2019.

DeGrippo said that to counteract CopperStealer, Proofpoint researchers reverse-engineered the malware. They then did the same to the domain generation algorithm (DGA) used in the malware, so they could preempt the attackers from registering domains used by the malware at least one day before the attackers could register them. They then went to the domain registrars that manage those domains and in most cases the registrars agreed to take them down.