CVE-2023-4035 – Simple Blog Card < 1.31 - Contributor+ Stored XSS via Shortcode

In our recent in-depth security analysis of the widely used Simple Blog Card plugin for WordPress, a concerning vulnerability has come to light. Versions prior to 1.31 have a critical flaw, leaving your website exposed to potential Stored Cross-Site Scripting (XSS) attacks!

Main info:

CVE	CVE-2023-4035
Plugin	Simple Blog Card
Critical	High
Publicly Published	August 2, 2023
Last Updated	August 2, 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-2023-4035 https://wpscan.com/vulnerability/8fd9192a-2d08-4127-adcd-87fb1ea8d6fc
Plugin Security Certification by CleanTalk

Timeline

July 31, 2023	Plugin testing and vulnerability detection in the Simple Blog Card plugin have been completed
July 31, 2023	I contacted the author of the plugin and provided a vulnerability PoC with a description and recommendations for fixing
August 1, 2023	The author has eliminated the vulnerability and patched his plugin
August 2, 2023	Registered CVE-2023-4035

Discovery of the Vulnerability

During a comprehensive security assessment of the Simple Blog Card plugin for WordPress, an alarming vulnerability was discovered in versions prior to 1.31. The plugin fails to validate and escape some of its shortcode attributes before rendering them on a page or post. This oversight can potentially enable users with the contributor role and above to execute Stored Cross-Site Scripting (XSS) attacks.

Understanding Cross-Site Scripting (XSS)

Cross-Site Scripting (XSS) is a dangerous attack that allows attackers to inject malicious scripts into web pages, affecting other users who visit the compromised page. In this context, attackers can exploit the Simple Blog Card plugin by embedding specially crafted shortcodes on a new page and submitting it for review by an administrator. When the administrator approves the page, the stored XSS attack is executed, and the consequences can be severe.

Exploiting the Stored Cross-Site Scripting (XSS) vulnerability

An attacker creates a seemingly harmless blog post containing a Simple Blog Card shortcode with malicious script injections. When an unsuspecting administrator approves the post, the malicious scripts execute within the browser of anyone viewing the page, leading to unauthorized data access, cookie theft, or other harmful actions.

POC shortcode:

[simpleblogcard url=”http://***.*/” color=’red;” onmouseover=”alert(111111)”‘]

This shortcode can be inserted into a new post

Potential Risks and Real-World Impact

The XSS vulnerability in the Simple Blog Card plugin poses serious risks to both website administrators and visitors. Some potential real-world scenarios include:

1. Unauthorized Data Access:
   Attackers could exploit the XSS vulnerability to steal sensitive user data, such as login credentials or personal information.
   
2. Cookie Theft:
   Malicious scripts could hijack user cookies, leading to unauthorized access to user accounts or session hijacking. After account takeover attacker can insert malicious PHP code on page and it will be RCE.
   
3. Malicious Content Distribution:
   Attackers might use the vulnerability to inject harmful content or links into the website, potentially damaging the site’s reputation or spreading malware.

Recommendations for Improved Security

To mitigate the risks associated with this vulnerability and enhance overall security, the following measures are strongly advised:

• Immediate Plugin Update:
  Website administrators should update the Simple Blog Card plugin to version 1.31 or higher, which addresses the XSS vulnerability.
  
• Input Validation and Escaping:
  Plugin developers must implement robust input validation and escaping mechanisms to ensure that all user-generated content, including shortcodes, is properly sanitized before rendering on the page.
  
• Regular Security Audits:
  Conduct regular security assessments and penetration tests on WordPress installations to identify and remediate potential vulnerabilities proactively.
  
• User Privilege Restriction:
  Implement strict access controls to ensure that users can only access information that they are authorized to view based on their roles and permissions.
  
• User Awareness:
  Educate website administrators and users about the risks of sharing sensitive information and the importance of strong, unique passwords.
  
  

By addressing the XSS vulnerability in the Simple Blog Card plugin and adhering to these security recommendations, website owners can protect their systems from malicious attacks, safeguard user data, and preserve the integrity of their websites. Stay safe and secure in the ever-evolving digital landscape!

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