CVE-2023-21775: Critical Microsoft Edge Remote Code Execution Vulnerability Exploitable by Malicious Websites

A critical security vulnerability, identified as CVE-2023-21775, has been discovered in the Chromium-based Microsoft Edge browser. This bug can cause remote code execution (RCE) attacks, allowing cybercriminals to gain unauthorized access to a victim's device when visiting a specially crafted website. If successfully exploited, this vulnerability could lead to a wide range of malicious activities, including data theft, ransomware infections, and unauthorized control of the affected system.

This long-read post will delve deeper into the details of this vulnerability, including code snippets, links to original references, and understanding how the exploit works. The aim is to spread awareness about this critical bug and help users safeguard their systems by applying the necessary precautions.

Vulnerability Description

The vulnerability lies in Microsoft Edge's handling of certain web content structures when rendering a web page. A flaw in the browser's implementation could result in the execution of arbitrary code on the user's device. This can be triggered by merely visiting a malicious website specifically designed to exploit this vulnerability.

As per the Common Vulnerability Scoring System (CVSS), the CVE-2023-21775 vulnerability has been assigned a score of 9.8, indicating that it is a critical threat with severe consequences if allowed to persist.

Technical Details

The CVE-2023-21775 vulnerability arises due to a use-after-free bug within Microsoft Edge's rendering engine. The problem begins when the browser attempts to process a malformed web page, causing improper memory management. Consequently, an attacker can manipulate the web page in a way that allows them to execute arbitrary code on the target device.

An example of a code snippet that could trigger this vulnerability is as follows

function exploit() {
    var maliciousObject = document.createElement('div');
    document.body.appendChild(maliciousObject);
    maliciousObject.outerHTML = '<iframe></iframe>';
    maliciousObject.remove();
    maliciousObject.innerHTML = '<img src="/malicious_image">';
}

In this code snippet, the attacker creates a div element and adds it to the document body. The outerHTML property of the div is then changed to an iframe, while the innerHTML is updated to include an image hosted on a malicious server. The improper memory management within the renderer allows the code to execute, leading to remote code execution.

Exploit Details

The attacker first needs to create a malicious web page to exploit this vulnerability. By utilising the above code snippet, they can construct a web page that successfully triggers the use-after-free bug.

The next step involves luring victims to visit the malicious web page. This can be accomplished through various social engineering tactics, such as sending the victim phishing emails or text messages containing the link to the malicious site.

Once the victim visits the infected website, the attacker can execute arbitrary code on their device remotely. This level of control enables criminals to inflict severe damage, such as stealing sensitive data, encrypting files, and deploying additional malware.

For more information on CVE-2023-21775, you can explore the following references

1. Official CVE Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-21775
2. Microsoft Security Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21775

Conclusion

The CVE-2023-21775 vulnerability in the Chromium-based Microsoft Edge presents a serious threat due to its remote code execution capabilities and severe consequences if successfully exploited. It is highly recommended for all users to ensure they apply any available patches or updates to mitigate this risk.

In addition, users should maintain a watchful eye for potential phishing attempts and exercise caution when clicking on unknown web links. By staying aware and proactive, we can better protect our systems and sensitive information from cybercriminals seeking to exploit vulnerabilities like CVE-2023-21775.

Timeline

Published on: 01/24/2023 00:15:00 UTC
Last modified on: 02/01/2023 14:54:00 UTC