Even the BSI warns of the CVE-2023-23397 vulnerability in Outlook, as it can be exploited without a single click from a user. Tenable experts tested a simple scenario in which the attack succeeds even though the email was only received and not clicked.
The youngest Reporting of Outlook vulnerability CVE-2023-23397 prompted Tenable to shed a little more light on the subject. A comment from Satnam Narang, Senior Staff Research Engineer at Tenable. While private users or single-user PCs are usually automatically protected by Windows updates, administrators have to check or roll out the patch themselves.
Dangerous zero-click vulnerability
“Within 24 hours of publication, MDSec researchers have already developed a functional proof-of-concept exploit for CVE-2023-23397, demonstrating how easy it is to exploit. In this example, they were able to exploit the vulnerability through an Outlook appointment reminder that appeared on the screen after the specially crafted message was received by the email server and downloaded by the Outlook client.
It required no user interaction, making this a zero-click vulnerability. Additionally, Microsoft confirmed that the flaw was exploited as a zero day as part of limited attacks by a Russia-based threat actor on target government, transport, energy, and military organizations in Europe.
Is the big attack yet to come?
Due to the ease with which this vulnerability can be exploited, we believe it is only a matter of time before it enters the playbooks of other threat actors, including ransomware groups. Tenable anticipates that CVE-2023-23397 will be one of the top vulnerabilities of 2023.
Like us in ours current Threat Landscape Report 2022 have highlighted, known vulnerabilities pose the greatest risk to organizations today. Now that CVE-2023-23397 has gone from a zero-day to a known vulnerability, we encourage all organizations using Microsoft—especially Outlook—to patch it Prioritize bugs sooner rather than later.”
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