You were probably affected by https://blog.mikrotik.com/security/winbox-vulnerability.html.
See this very recent related thread: http://forum.mikrotik.com/t/router-sending-spam/123683/1
You were probably affected by https://blog.mikrotik.com/security/winbox-vulnerability.html.
See this very recent related thread: http://forum.mikrotik.com/t/router-sending-spam/123683/1