CVE-2023-36757 is a critical spoofing vulnerability that has been identified in Microsoft Exchange Server, posing a potential threat to businesses and organizations using this popular email server. In this long-read article, we will delve into the technical details of the vulnerability, discuss how attackers can exploit it, and provide guidance on how to protect Exchange Servers from this threat.

Vulnerability Summary

Microsoft Exchange Server, being a widely used email platform, has been a target of numerous attacks and vulnerabilities in the past. CVE-2023-36757 is a new vulnerability that falls into the category of spoofing attacks. Spoofing refers to a situation where an attacker pretends to be someone else by falsifying their email address or other identifying information. In the context of Exchange Server, this vulnerability allows an attacker to bypass certain security features, enabling them to send and deliver malicious emails impersonating a legitimately existing email user.

Exploit Details

The vulnerability stems from Exchange Server's improper handling of email validation and sender verification. An attacker can exploit this weakness by crafting a specially constructed email that will make the email server think it's from a legitimate user and pass through all the security checks. Here's a code snippet that demonstrates how to craft a spoofed email that can bypass certain protection mechanisms:

//Creating a new email message
EmailMessage email = new EmailMessage();
email.From = new EmailAddress("");

//Setting up the spoofed email headers
email.Headers.Add("X-Original-SENDER", "");
email.Headers.Add("X-Original-RECEIVER", "");
email.Subject = "IMPORTANT - CVE-2023-36757";
email.Body = "This is a spoofed email that exploits CVE-2023-36757 vulnerability in Exchange Server.";

Compromise sensitive information or gain unauthorized access to network resources.

For a comprehensive list of the affected Exchange Server versions and their severity, please refer to the CVE-2023-36757 Vulnerability Details by Microsoft.

Mitigation Steps

Microsoft has released security updates and patches to address this vulnerability for all the affected Exchange Server versions. The following steps are recommended to mitigate the risk associated with CVE-2023-36757:

1. Apply the security updates as soon as possible. For specific guidance on how to apply these updates, refer to Microsoft's Update Guide.

2. Review and implement email security best practices, such as DKIM (DomainKeys Identified Mail), SPF (Sender Policy Framework), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). These technologies help to authenticate emails and prevent spoofing attacks from succeeding. For detailed guidance, refer to Microsoft's Anti-spoofing Protection Guide.

3. Monitor email traffic and related logs for any suspicious activities or signs of a successful spoofing attack. Regularly check the email server logs to identify potential compromises.

4. Educate users and employees about the dangers of email-related attacks, such as phishing and spoofing. This will raise their awareness and help them recognize potentially malicious emails.


CVE-2023-36757 is a critical spoofing vulnerability in Microsoft Exchange Server that can be exploited by attackers to send malicious emails impersonating legitimate users. By taking appropriate measures to mitigate this risk, organizations can protect their email communication and message integrity. By staying vigilant and keeping your software updated, you can minimize the chances of falling victim to such attacks.


Published on: 09/12/2023 17:15:00 UTC
Last modified on: 09/12/2023 19:38:00 UTC