@SaintWacko I greatly oversimplified, in part because I didn't quite understand it yet
Basically, their monitoring software uses strings formatted in a specific way to know what to monitor. Those strings are parsed with Regex and then stored in an array, which is sent to be interpreted. The problem is that an interpreter they added in February expected that array to have 21 elements, but due to a bug in the regex related to wildcards that array actually had 20. The reason it worked until it didn't was because the 21st element hadn't been used up until that point
Then, when the 21st element eventually WAS used by the interpreter, it triggered an array index out of bounds error, and because this was in a kernel level driver loaded on boot, it threw Windows into a boot loop