level0 done

level0/source.c

@@ -0,0 +1,23 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+int main(int ac, char **av)
+{
+	char *cmd;
+
+	int nb = atoi(av[1]);
+	if (nb == 423) {
+		cmd = strdup("/bin/sh");
+		gid_t gid = getegid();
+		uid_t uid = geteuid();
+		setresgid(gid, gid, gid);
+		setresuid(uid, uid, uid);
+		execv("/bin/sh", &cmd);
+	} else {
+		fwrite("No !\n", 1, 5, (FILE *)stderr);
+	}
+	return 0;
+}