The experts from McAfee are warning of a new cyberattack that silently installs malware on the computers containing Microsoft Office  Word. The users of this software should be very careful when opening Word documents downloaded from third-party websites or attached to unknown e-mail messages.

Since the beginning of 2017 the unknown group of hackers have been exploiting a serious – and yet unpatched – zero-day vulnerability present in all modern versions of Microsoft Office Word software. The cyberattack begins by downloading a malicious HTA file disguised as a Microsoft's RTF. When opened, the malicious code gets executed, granting the cyberattackers almost complete control over the victim's computer.

The switch to document exploits by the hackers represents a change of tactics that previously leaned heavily on malicious Macros to distribute their wares. So far the newly discovered tactic have proven to be effective against all fully-patched Windows operating systems including the newest and the most secure version – Windows 10.

The producer of the Word software – Microsoft company – is aware of the zero-day vulnerability but has not yet issue any sort of public advisory. For now it is better not to open RTF documents from unknown sources.