A cyber-espionage campaign targeting older versions of Microsoft’s SharePoint software has affected around 400 organizations, according to Netherlands-based Eye Security.
European cybersecurity firm said this figure is based on digital traces found during scans of compromised servers and is likely an undercount.
Eye Security’s chief hacker Vaisha Bernard said many attacks did not leave detectable evidence. Over the weekend, the number of known victims was around 100.
The campaign began after Microsoft failed to completely fix a vulnerability in its SharePoint server software. Attackers quickly moved to exploit the flaw once it was discovered.
Microsoft and Alphabet have both said that hackers linked to China are behind the campaign. China has denied the allegation.
The names of most affected organizations have not been revealed. Bernard declined to provide further details.
