Telefónica’s cybersecurity arm ElevenPaths developed a privacy-protecting malware detector that scans Microsoft Office 365 and PDF documents without processing the content of the files.

It’s called Diario, which means diary, and Teleónica already uses it internally. Diario is now available to external users, which can download and use the malware detector for free. The more users the better, “because all their knowledge is shared and the formula can continue to be improved and extended to other kinds of files,” the company said in a statement.

According to ElevenPaths, Diario uses a new type of artificial intelligence (AI) specifically trained to detect malware that generally evades traditional antivirus technology. It extracts certain functionalities from the files — but not the content — and sends them to the server, which scans and detects whether the documents contains malware while also guaranteeing the privacy of the content.

It’s also particularly timely as Microsoft Office becomes even more of a necessity with millions of employees now working remote because of the COVID-19 pandemic. SonicWall’s recently released mid-year threat report found a 176% increase in new malware attacks disguised as trusted Microsoft Office file types.

ElevenPaths trained Diario’s machine learning model with malicious indications that are harder for traditional antivirus tools to recognize, and while it’s not designed to replace antivirus products, it bridges the gap that endpoint security technologies cannot cover.

The new tool targets two groups of users: those who want to use the prediction service without compromising the document data and security analysts who can benefit from the database of detected threats without having access to any private data in the documents.

“On many occasions we receive an email with a document supposedly containing a file attachment with confidential information that comes from a legitimate and known source and which, despite having passed through the mail’s antivirus filter, may contain some type of malware,” said Sergio de los Santos, ElevenPaths’ Innovation Lab director, in a statement. “In these cases, using Diario allows us to add an additional layer of security to the gateway antivirus that has failed, without jeopardizing the content of the document in the event that it’s actually confidential.”