The vulnerability that allowed remote code execution via the Windows Support Diagnostic Tool (MSDT) has been fixed in the June 14 Patch Tuesday release by Microsoft. 

A researcher dubbed the vulnerability “Follina” since the zero-day code references 0438, which is the area code fo Follina, Italy, after it was discovered over the Memorial Day weekend. 

In a June 14 update to its May 30 guidance for disabling the MDST URL protocol vulnerability from a calling application such as Word, Microsoft recommended installing the updates as soon as possible.

“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.”

The vulnerability was actively exploited by a number of state-sponsored hacking groups, as well as other threat actors, according to Bleeping Computer.

Paul Ducklin at Sophos’ Naked Security blog confirmed that applying the June Cumulative Updates suppresses the bug in its brief testing.

Scott Walsh, senior security engineer for cyber insurance firm Coalition, encouraged organizations to maintain good cybersecurity hygiene by patching services such as Exchange, review logs and permissions for any devices open to the internet.

“It’s important for organizations to pay equal attention to the security of individual user machines as Follina is currently a vulnerability that is triggered by the user,” Walsh said. “While Follina may not immediately provide a server-level threat to organizations, security gets worse over time if organizations do nothing.”