Part of the Belgian Ministry of Defence's network was down for several days as a result of a "serious" cyber attack after a security hole was discovered in the software.
Since last Thursday, part of the computer network was down, including the mail system, as a result of the attack. It remains unclear who the perpetrator is, according to reports from VRT News.
"The Defence Ministry discovered an attack on its computer network with internet access on Thursday. Quarantine measures were quickly taken to isolate the affected parts. The priority is to keep the Defence network operational," said spokesperson Olivier Séverin.
He added that the team was mobilised throughout the weekend to keep problems under control, and to continue activities where possible, while monitoring the ongoing situation.
According to the Ministry of Defence, the attack is a result of Log4Shell critical vulnerability, a bug in the security of Apache's widely used software Log4j, an open-source Java logging library created by the Apache Foundation which is widely used by developers to keep a record of activity within an application.
This issue has raised concerns beyond the cyber security community, as Log4j is a software component used by millions of computers worldwide running online services, making it potentially the most severe computer vulnerability in years, according to the United Kingdom's National Cyber Security Centre (NCSC).
The bug in the technical framework could leave various software vulnerable to hackers, of whom many are now actively scanning to detect systems that have this weakness so that they can take control of vulnerable systems remotely.