The development of technology caused the possibility of non-conventional war that can’t be predicted by human’s intelligence. Cyber becomes the most vulnerable media for war. Because this media offers the attacker to hide its identity and attack anyone they want. In some case cyber-attack could cause stoppage of a country’s activity if cyber is one of the country’s most important thing. The cyber-war of Estonia in 2007 was the first and biggest cyber-war towards a country in history. The attack could cause the stoppage of the country’s activity. Russia was the only possible one to blame. In order to react to this case Estonia called NATO for help to finish the case.As the world went to 4.0 industrial revolution era, Indonesia needed to also be aware of cyber attacks. Therefore, Estonian Cyberattacks should become reflection and awareness for Indonesia in deterring possible cyberattacks in the future.