CVE-2012-5502 in Plone
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in safe_html.py in Plone before 4.2.3 and 4.3 before beta 1 allows remote authenticated users with permissions to edit content to inject arbitrary web script or HTML via unspecified vectors.
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Analysis
by VulDB Data Team • 03/13/2019
The CVE-2012-5502 vulnerability represents a critical cross-site scripting flaw within the Plone content management system that affects versions prior to 4.2.3 and 4.3 beta 1. This vulnerability specifically resides in the safe_html.py module which is responsible for sanitizing HTML content to prevent malicious scripts from being executed. The flaw enables authenticated users with editing privileges to bypass the HTML sanitization mechanisms and inject arbitrary web scripts or HTML code into the application. The vulnerability is particularly concerning because it leverages the trust relationship between the application and authenticated users who possess legitimate editing permissions, making it difficult to detect and prevent through standard security measures. The unspecified vectors indicate that the attack surface encompasses multiple potential injection points within the HTML processing pipeline, suggesting that the sanitization logic fails to properly validate or escape various HTML elements and attributes.
This vulnerability directly maps to CWE-79 which defines Cross-Site Scripting as a weakness that occurs when an application includes untrusted data in a new web page without proper validation or escaping, allowing attackers to execute scripts in the victim's browser. The attack scenario involves an authenticated user who can manipulate content through the Plone interface, potentially exploiting the XSS flaw to inject malicious scripts that will execute when other users view the compromised content. The operational impact extends beyond simple script execution as these XSS vulnerabilities can be leveraged to perform session hijacking, defacement of content, data theft, or redirection to malicious sites. The vulnerability demonstrates a failure in the principle of least privilege and input validation, where the application trusts user-provided content without adequate sanitization before rendering it to other users.
The exploitation of this vulnerability requires an authenticated user with editing permissions, which means that the attack vector is limited to users who have already compromised legitimate access to the system. However, this limitation does not diminish the severity of the vulnerability since it can be exploited by insiders or by attackers who have gained user credentials through other means such as credential stuffing, phishing, or other authentication bypass techniques. The impact on the organization can be significant as compromised user sessions could lead to unauthorized access to sensitive content, modification of critical information, or the ability to spread malicious payloads to other users within the Plone environment. The vulnerability also represents a potential escalation path for attackers who may use it as a foothold to gain further access to the system or to launch more sophisticated attacks against other components of the application stack.
Organizations utilizing affected Plone versions should immediately implement the available patches and updates to remediate this vulnerability. The recommended mitigations include upgrading to Plone versions 4.2.3 or later, which contain the necessary security fixes. Additionally, administrators should review and tighten user permission settings to minimize the number of users with editing privileges, implementing the principle of least privilege to reduce the potential attack surface. Input validation and output encoding should be enhanced at multiple layers including application-level sanitization, database-level filtering, and proper HTML escaping mechanisms. Security monitoring should be implemented to detect unusual content modification patterns that might indicate exploitation attempts. The vulnerability also underscores the importance of regular security assessments and penetration testing to identify similar issues in web applications, particularly those involving HTML processing and user-generated content handling. Organizations should also consider implementing web application firewalls and content security policies to provide additional defense-in-depth measures against similar XSS vulnerabilities.