There are two problems with this template, it only checks for chmod commands but most importantly doesn't check for html tags. A real history file the response doesn't include html tags at all.
So, I'm adding two rules: Check for another possible commands (from real example) and adding a negative rule to discard false positives like this one:
nuclei -debug -t /home/kali/nuclei-templates/misconfiguration/shell-history.yaml -u http://777.urbanup.com