A report in Ars Technica said the warning about the botnet came from Dale Drew, the chief security strategist at broadband provider CenturyLink.
The source code for Mirai was leaked on the Hackforums community last year by someone using the pseudonym Anna-Senpai.
Since then, there have been numerous tweaks to the code and numerous versions accordingly released. The original Mirai was used in DDoS attacks that hit Twitter, GitHub and the PlayStation Network among others.
Ars said the new malware had 65,000 username and password combos to try to gain access to devices that it attacked.
Huawei has been contacted for comment.