Microsoft Outlook, the popular email client, is in the news again, but not for good reasons. Security researchers have identified a zero-day vulnerability in the software that is easy to exploit and actively being exploited. In this article, we explore why this vulnerability is causing alarm and what steps you need to take to protect your system.
The Unusual Danger of the Privilege-Elevation Vulnerability
Unlike other exploits, the privilege-elevation vulnerability in Outlook is particularly dangerous because no user interaction is required to trigger the exploit. This means that an infected email arriving in a Microsoft Outlook inbox can compromise sensitive credential hashes without the user even opening the email.
How the Vulnerability is Exploited
The threat actor can capture Net-NTLMv2 hashes, a type of credential that can provide the attacker with authentication within Windows environments. This allows the attacker to potentially authenticate themselves as the victims, escalate privileges, or further compromise the environment.
The Urgent Call for Immediate Patching
The urgency of patching this vulnerability cannot be overstated. Security experts are advising all users of Microsoft Outlook for Windows to update their software immediately to remain secure. The vulnerability is being actively exploited, and the longer the system remains unpatched, the more vulnerable it becomes.
The Ongoing Threat Even with Patch Deployed
There is evidence that even with the patch deployed, the critical-severity vulnerability can still be exploited under certain conditions. Microsoft has acknowledged the possibility but noted that the technique for doing so requires an attacker to already have gained access to internal networks.
Five Critical Things to Know about the Outlook Vulnerability
- The privilege-elevation vulnerability in Outlook is considered easy to exploit and is being actively exploited.
- The vulnerability can compromise sensitive credential hashes without the user even opening the email.
- The attacker can capture Net-NTLMv2 hashes, which allows them to potentially authenticate themselves as the victims and escalate privileges.
- All users of Microsoft Outlook for Windows are strongly advised to update their software immediately.
- Even with the patch deployed, the vulnerability can still be exploited under certain conditions.
Dimitris is an Information Technology and Cybersecurity professional with more than 20 years of experience in designing, building and maintaining efficient and secure IT infrastructures.
Among others, he is a certified: CISSP, CISA, CISM, ITIL, COBIT and PRINCE2, but his wide set of knowledge and technical management capabilities go beyond these certifications. He likes acquiring new skills on penetration testing, cloud technologies, virtualization, network security, IoT and many more.