Cyber attackers are day today increasing and the attackers are always one step ahead to launching sophisticated cyber attackers which is very difficult to detect and mitigate.
Basically .CSV files could be opened in MS Excel when you click on a common .CSV file and interprets cells contents.
In this case, the Attacker embedded the malware dropper within the Google spreadsheet to infect the users and its launching via spam emails.
Spreading the malware via Google Spread Sheet is create more trust among the normal peoples without bothering about who send it but security community never trust it.
Google basically implemented the sophisticated gMail and gDrive anti Malware techniques in order to avoid Malware spreading over its amazing technologies by avoiding specific file type (.exe, .dll, .zip, etc etc) over gMail.
But an attacker bypass this Google filter technique and they easily use Google Sheets as a Malware vector. anyhow, Google has been alerted about this issue but it confirmed that it’s actually an “Intended Behaviour”.
According to the researcher, Finally, an attacker could send a clear link over an instant message platform and/or over an email asking to open up a Google Sheets suggesting to the victim to open the spreadsheet locally since “MSExcel compatibility issues”. At that time if the victim downloads the Google sheets and opens up locally (with Microsoft), the attacker might infect her box”
Users need to aware of this kind of serious attacks, avoid to download links if you receive a link to a not working Google Sheets.