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The Centre for Cyber Security Belgium (CCB) is warning Belgian companies using Microsoft Exchange Servers of a system vulnerability.

Hackers have penetrated numerous computer servers of companies, organizations and government agencies worldwide since January, Microsoft reports. The company found a series of vulnerabilities in its Exchange servers. These are email servers used by thousands of companies and organizations. Belgian organizations are also using this solution and may be victims.

The CCB published an advisory document on 3 March recommending that priority should be given to installing updates on external Exchange servers. All affected Exchange servers should be updated with the highest priority. CERT.be's advisory document is continuously updated. Those who want to stay up to date with the latest security updates can follow CERT.be on Twitter.

New updates are released regularly and should be installed quickly. It is also important to reboot the system after an update and to check all systems regularly for indications of compromise.

Miguel De Bruycker, Director of Centre for Cyber Security Belgium

The CCB seeks to identify vulnerable and compromised systems to inform their owners. Three Belgian victims provided provisional reports to us and were assisted.

Microsoft has set up a webcast with clear explanations. This is referred to in CCB's advisory document.

Microsoft has released several security updates for the Microsoft Exchange Server to fix vulnerabilities used in limited and targeted attacks.

Belgian victims can always report cyber incidents to CERT.be.

The Centre for Cyber Security Belgium is closely monitoring the situation.