I came across the article. Anyone who mines with Bitmain Antminers should see this article. Hope this helps " Antbleed is a backdoor introduced by Bitmain into the firmware of their bitcoin mining hardware Antminer.
The firmware checks-in with a central service randomly every 1 to 11 minutes. Each check-in transmits the Antminer serial number, MAC address and IP address. Bitmain can use this check-in data to cross check against customer sales and delivery records making it personally identifiable. The remote service can then return "false" which will stop the miner from mining.
The patch was introduced here (pastebin) and can be seen in the source: here (github)
At worst, this firmware backdoor allows Bitmain to shut off a large section of the global hashrate (estimated to be at up to 70% of all mining equipment). It can also be used to directly target specific machines or customers. Standard inbound firewall rules will not protect against this because the Antminer makes outbound connections.
Even without Bitmain being malicious, the API is unauthenticated and would allow any MITM, DNS or domain hijack to shutdown Antminers globally. Additionally the domain in question DNS is hosted by Cloudflare making it trivially subjected to government orders and state control."
"Around 70% of Bitcoin hashrate affected
Bitcoin Core developer Peter Todd says "any MITM attacker or DNS attacker can activate it [Antbleed backdoor]" as there is no authentication mechanism included in the firmware."
https://www.bleepingcomputer.com/news/security/backdoor-code-discovered-in-popular-bitcoin-mining-equipment/
http://www.antbleed.com/