CVE-2016-4566 in Plupload
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in plupload.flash.swf in Plupload before 2.1.9, as used in WordPress before 4.5.2, allows remote attackers to inject arbitrary web script or HTML via a Same-Origin Method Execution (SOME) attack.
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Analysis
by VulDB Data Team • 10/01/2024
The vulnerability identified as CVE-2016-4566 represents a critical cross-site scripting flaw in the Plupload flash component that affected widely used content management systems including WordPress. This vulnerability specifically targets the plupload.flash.swf file, which serves as a Flash-based uploader component within the Plupload library. The issue arises from insufficient input validation and sanitization mechanisms within the Flash SWF file, creating a pathway for malicious actors to execute arbitrary code within the context of a victim's browser session. The vulnerability is particularly concerning because it operates through a Same-Origin Method Execution attack vector, which leverages the trust relationship between Flash components and web applications to bypass traditional security restrictions.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input that gets processed by the Flash component without proper sanitization. The Flash SWF file, being a binary Flash application, handles file uploads and processing operations that are typically performed within the browser's security context. When the SOME attack is successful, it allows attackers to inject malicious scripts that execute in the same origin context as the legitimate web application, thereby bypassing standard cross-origin restrictions that normally protect against such attacks. This method of exploitation is particularly dangerous because it can leverage the trusted relationship between Flash components and the web application, making it difficult to detect and prevent through conventional security measures.
The operational impact of this vulnerability is significant for WordPress installations and other platforms that utilize the affected Plupload library versions. Attackers could potentially execute malicious scripts that could steal user session cookies, redirect users to phishing sites, or perform actions on behalf of authenticated users. The vulnerability affects WordPress versions prior to 4.5.2, which represents a substantial portion of installations at the time of discovery. This allows attackers to compromise user accounts, manipulate content, or establish persistent access to vulnerable systems through the execution of malicious code within the browser context of legitimate users. The impact extends beyond individual user compromise to potential system-wide security breaches when administrators or privileged users interact with compromised upload functionality.
Mitigation strategies for this vulnerability involve immediate patching of the affected WordPress installations to version 4.5.2 or later, which includes updated Plupload libraries that address the XSS vulnerability. Additionally, administrators should implement comprehensive input validation and sanitization measures for all user-supplied content, particularly file upload operations. Security measures should include content security policy implementations that restrict script execution and prevent unauthorized code injection. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for script-based execution. Organizations should also consider implementing web application firewalls and regular security audits to detect and prevent similar vulnerabilities in other components of their web applications. The remediation process requires careful testing to ensure that updated libraries do not introduce compatibility issues with existing functionality while maintaining the security posture against future exploitation attempts.