What are these pesky core.12345 files I am seeing on my account and they are using up space.
Fortunately, core files are usually not present as a result of a hack. They are, rather, error files that explain why something in the account failed. When a program crashes, a core dump is triggered which writes the core file.
A core file is created when a program terminates unexpectedly, due to a bug or a violation of the operating system's or hardware's protection mechanisms. The operating system kills the program and creates a core file that programmers can use to figure out what went wrong. It contains a detailed description of the state that the program was in when it died.