diff --git a/level4/source.c b/level4/source.c
new file mode 100644
index 0000000..5be7903
--- /dev/null
+++ b/level4/source.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int m;
+
+void p(char *str)
+{
+	printf(str);
+	return;
+}
+
+void n(void)
+{
+	char buf[520];
+
+	fgets(buf, 512, stdin);
+	p(buf);
+	if (m == 0x1025544) {
+		system("/bin/cat /home/user/level5/.pass");
+	}
+	return;
+}
+
+int main(void)
+{
+	n();
+	return 0;
+}