Microsoft on 30/06/2022 published guidance for a newly discovered zero-day security flaw in its Office productivity suite that could be exploited to achieve code execution on affected systems.

The weakness, now assigned the identifier CVE-2022-30190, is rated 7.8 out of 10 for severity on the CVSS vulnerability scoring system. Microsoft Office versions Office 2013, Office 2016, Office 2019, and Office 2021, as well as Professional Plus editions, are impacted.

“To help protect customers, we’ve published CVE-2022-30190 and additional guidance here,” a Microsoft spokesperson said in an emailed statement.

The Follina vulnerability, which came to light late last week, involved a real-world exploit that leveraged the shortcoming in a weaponized Word document to execute arbitrary PowerShell code by making use of the “ms-msdt:” URI scheme. The sample was uploaded to VirusTotal from Belarus.

But first signs of exploitation of the flaw date back to April 12, 2022, when a second sample was uploaded to the malware database. This artifact is believed to have targeted users in Russia with a malicious Word document (“приглашение на интервью.doc”) that masqueraded as an interview invitation with Sputnik Radio.

“A remote code execution vulnerability exists when MSDT is called using the URL protocol from a calling application such as Word,” Microsoft said in an advisory for CVE-2022-30190.

“An attacker who successfully exploits this vulnerability can run arbitrary code with the privileges of the calling application. The attacker can then install programs, view, change, or delete data, or create new accounts in the context allowed by the user’s rights.”