Cross-Site Scripting (XSS) is a persistent and pervasive security concern for web applications. CVE-2023-4799 is a notable vulnerability that affects the “Magic Embeds” plugin, enabling the exploitation of Stored XSS via a shortcode. In this article, we’ll explore the discovery of this vulnerability, delve into the concept of Stored XSS, understand its implications, and provide recommendations for improved security.
Main info:
| CVE | CVE-2023-4799 |
| Plugin | Magic Embeds |
| Critical | High |
| Vulnerable sites | 378 693 |
| Publicly Published | October 28, 2023 |
| Last Updated | October 28, 2023 |
| Researcher | Dmtirii Ignatyev |
| OWASP TOP-10 | A7: Cross-Site Scripting (XSS) |
| PoC | Yes |
| Exploit | Will be later |
| Reference | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4799 https://wpscan.com/vulnerability/04c71873-5ae7-4f94-8ba9-03e03ff55180/ |
| Plugin Security Certification by CleanTalk |  |
Timeline
| September 6, 2023 | Plugin testing and vulnerability detection in the Magic Embeds plugin have been completed |
| September 6, 2023 | I contacted the author of the plugin and provided a vulnerability PoC with a description and recommendations for fixing |
| October 21, 2023 | The author removed the plugin from WP |
| October 21, 2023 | Registered CVE-2023-4799 |
Discovery of the Vulnerability
The vulnerability, designated as CVE-2023-4799, was unearthed during an evaluation of the “Magic Embeds” plugin for WordPress. The plugin allows users to seamlessly embed a variety of media content into their posts or pages, enhancing the visual appeal and interactivity of their websites.
Understanding of Stored XSS attack’s
Stored Cross-Site Scripting (Stored XSS) is a type of XSS attack in which malicious scripts are injected into a web application and saved on the server. When other users access the compromised page or content, the stored payload is served to them, often resulting in the execution of malicious scripts in their browsers. This allows attackers to perform actions on behalf of unsuspecting users.
In the context of CVE-2023-4799, the vulnerability enables an attacker to embed a malicious script within a shortcode in a new post. This script is stored on the server and subsequently executed when other users, especially those with Contributor or higher privileges, view the post. This can lead to an account takeover, giving the attacker control over the compromised user’s account.
Exploiting
Exploiting this vulnerability requires the attacker to have Contributor or higher privileges. They can craft a post that includes a specific shortcode containing the embedded malicious script. Once published, the malicious script is stored on the server. When other users view the compromised post, the script executes in their browsers, enabling the attacker to perform various unauthorized actions.
POC shortcode:
[fb_plugin video href=”https://www.facebook.com/facebook/videos/10153231379946729/” autoplay='” onmouseover=”alert(/XSS/)”‘ ]
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The CVE-2023-4799 vulnerability poses significant risks to affected web applications and users. An attacker who successfully exploits this vulnerability can potentially gain control over an account with Contributor or higher privileges. This could lead to various malicious activities, such as data theft, content manipulation, or spreading malware, compromising the overall security and integrity of the web application.
In real-world scenarios, an attacker might use this vulnerability to compromise websites or web applications that use the “Magic Embeds” plugin. They could impersonate users with higher privileges, causing damage to the platform and putting sensitive data at risk.
Recommendations for Improved Security
To bolster security and mitigate the risks associated with CVE-2023-4799, the following security measures are recommended:
- Plugin Updates: Ensure that the “Magic Embeds” plugin is up to date with the latest security patches and updates. Plugin developers often release patches to address vulnerabilities like Stored XSS.
- User Privilege Management: Carefully manage user privileges, especially for Contributor and higher roles. Users should only be granted necessary permissions to perform their tasks.
- Input Validation: Implement rigorous input validation and output encoding techniques to prevent XSS attacks. Always sanitize and validate user-generated content before processing or storing it.
- Security Audits: Periodically conduct security audits and vulnerability assessments to identify and rectify potential vulnerabilities before they can be exploited.
- User Education: Educate users, particularly those with administrative roles, about the risks of executing shortcodes and how to identify and handle potentially malicious content.
CVE-2023-4799 underscores the need for robust security practices in the development and use of WordPress plugins. Proactive vulnerability management and user awareness are essential to maintaining the security and reliability of web applications.
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