With Magento 1 nearing it's end of life in June 2020, what are the biggest threats when it comes to security?
With the Magento 1's end of life, the software support that includes quality fixes and security patches will stop. Owing to the end of security patches, the Magento stores will become vulnerable to the loopholes that are, for time being, secured with the SUPEE patches.
Also, if any loopholes are discovered in the future, Magento would not release the security fix for the same.
With no security measures, it becomes easy for hackers to access your admin panel and you surely do not want it!
That's why it is important to migrate the Magento stores to Magento 2 asap.