The International Criminal Court (ICC) headquartered at The Hague in the Netherlands has heightened its online security after detecting a serious cyber security incident five weeks ago, which it revealed was an act of espionage.

In a statement on Friday the ICC said that as soon as the incident was confirmed by its alert mechanism, steps were taken to mitigate its effects by initiating an immediate incident response with the support of the Netherlands as the “host state” and external cyber security experts. This included forensic analysis of the incident, its causes and its impact, and initial mitigating measures.

“The evidence available thus far indicates a targeted and sophisticated attack with the objective of espionage,” the ICC said.

“The attack can therefore be interpreted as a serious attempt to undermine the court’s mandate.  Based on the forensic analysis carried out, the court has already taken and will continue to take all necessary steps to address any compromise to data belonging to individuals, organisations and States. Should evidence be found that specific data entrusted to the court has been compromised, those affected would be contacted immediately and directly by the court,” it said.

The ICC said that with the information currently available it is not possible to confirm who is responsible for the attack but the Dutch law enforcement authorities are currently conducting a criminal investigation.

As a result of the attack, the court is reinforcing its risk management framework and identifying actions and procedures to be ready to respond to any potential repercussions from the cyber-attack including any potential security risk to victims and witnesses, court officials and the court’s operations, the ICC said.

“As part of broader assessment into potential actions by threat actors, the court has also identified that disinformation campaigns targeting the ICC and its officials may be anticipated to be launched in an effort to tarnish the ICC image and delegitimise its activities. The court is also accelerating a number of existing initiatives aimed at enhancing digital security,” it said.

The ICC said it will be working together in addressing the increasing risk of cyber-attacks and the need to protect the institution to ensure its capacity to implement the ICC’s critical mandate of justice and accountability, which is a shared responsibility of all States Parties.