Belgium has launched a judicial investigation into a cyber incident affecting the email system of its state security service (VSSE), the federal prosecutor's office confirmed this week. The inquiry follows a complaint filed by the VSSE regarding unauthorised access to its communications infrastructure.

According to a report by Belgian newspaperLe Soir, the breach, attributed to an unidentified state-affiliated threat actor, led to the interception of approximately 10% of the agency's external email traffic between 2021 and 2023. The compromised system handled communications with government entities, law enforcement, and public prosecutors, while classified internal correspondence reportedly remained unaffected.

The intrusion is believed to have exploited a known vulnerability in an email security product developed by the US cybersecurity firm Barracuda Networks. In 2023, cybersecurity researchers identified that a Chinese-linked threat group, tracked as UNC4841, had leveraged this vulnerability in attacks targeting government and private-sector organisations across multiple regions, including Europe.

Belgian authorities have not disclosed specific details regarding the scope of the breach but confirmed that an internal assessment is underway. Concerns have been raised about potential exposure of personal data related to VSSE personnel, as the affected server also processed human resources-related correspondence. Officials have advised affected individuals to review security measures, though there is no confirmation of data misuse at this stage.

The Belgian government has not officially attributed the attack to a specific actor. The VSSE and federal prosecutor's office have stated that further updates will depend on the findings of the ongoing inquiry.

The Chinese Embassy in Belgium denied the accusations and pointed to a lack of evidence to sustain the Belgian government's claims.

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