Note this isn't the 'right' way to do it in a 1st world country, but for the purposes of casual thieves common to the area it was installed more than sufficient. I use expanding raw-plugs when the better way is using expanding masonry bolts and then the screws etc.
Once upon a time I had one of these document safes that has a reasonable fire rating. It cost around $130. Burglars pried and or kicked in the back door of the house, using a couple of crowbars I had conveniently left available for them in the carport. They also used them to breach this fire safe with very little effort. . The whole purpose of this post is to suggest a good fire rated high quality gun safe, and bolt that down to a concrete floor. jmho ..... it wouldn't hurt to conceal it in some way also.
Safes are not safes--a buds was gotten into with just a crow bar. All you can do is slow their entry by hiding or doubling the entry time. A bud put a "bra" around his controls with a shielded lock. Only way in would be with a torch. Inside he has a surprise--an opened gallon can of BP just sitting there waiting on a spark.