I've installed libapache-mod-security on Ubuntu 10.04. The only configuration file I've been able to find is this one:
# cat /var/lib/dpkg/info/libapache-mod-security.conffiles
/etc/apache2/mods-available/mod-security.load
However, this does not match the configuration file mentioned in the mod_security documentation. It only tells Apache in which directory to find the module. Where are the mod-security rules stored?
Maybe try /etc/apache2/conf.d/modsecurity2.conf ?
-edit-
This apparently applies to all versions of Ubuntu: mod_security
Ubuntu is well known to change configuration file without any reason (they did alot with apache).
So try to search the internet for apache conf file in unbuntu or try the locate command (with proper file name) and you'll maybe find what you're searching for.
You may try following command.
It works on Ubuntu 18, not sure about Ubuntu 10.04