CVE-2011-5051 in WP Symposium
Summary
by MITRE
Multiple unrestricted file upload vulnerabilities in the WP Symposium plugin before 11.12.24 for WordPress allow remote attackers to execute arbitrary code by uploading a file with an executable extension using (1) uploadify/upload_admin_avatar.php or (2) uploadify/upload_profile_avatar.php, then accessing it via a direct request to the file in an unspecified directory inside the webroot.
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Analysis
by VulDB Data Team • 11/28/2021
The CVE-2011-5051 vulnerability represents a critical security flaw in the WP Symposium plugin for WordPress systems, affecting versions prior to 11.12.24. This vulnerability stems from inadequate input validation and file upload restrictions within the plugin's avatar upload functionality, specifically in two distinct upload endpoints. The issue creates a pathway for remote attackers to gain unauthorized code execution capabilities by leveraging unrestricted file upload mechanisms. The vulnerability is particularly dangerous because it allows attackers to upload malicious files with executable extensions directly into the web application's directory structure, bypassing normal security controls that should prevent such operations.
The technical exploitation of this vulnerability occurs through two primary vectors within the plugin's uploadify functionality. The first vector involves the upload_admin_avatar.php endpoint, while the second utilizes upload_profile_avatar.php endpoint. Both paths allow attackers to upload files with potentially malicious payloads that can be executed within the web server context. The vulnerability's design flaw lies in the lack of proper file type validation and extension checking mechanisms. Attackers can upload files with extensions that are executable or interpreted by the web server such as .php, .asp, .aspx, or other script extensions, which are then accessible through direct HTTP requests to the uploaded files within the webroot directory structure. This creates a persistent backdoor or execution point that remains active until the malicious files are manually removed or the plugin is updated.
The operational impact of CVE-2011-5051 extends beyond simple code execution to encompass complete system compromise potential. Once an attacker successfully uploads a malicious file, they can execute arbitrary commands on the web server, potentially leading to full system control, data exfiltration, or the establishment of persistent access points. The vulnerability's implications are particularly severe in shared hosting environments or when WordPress installations are not properly maintained, as the attack surface expands to include not just the vulnerable plugin but potentially the entire web application infrastructure. The unspecified directory location within the webroot creates additional complexity for defenders, as the exact path of uploaded files may vary based on server configuration, making detection and remediation more challenging.
This vulnerability aligns with CWE-434, which specifically addresses "Unrestricted Upload of File with Dangerous Type," and represents a classic example of insecure file upload handling that enables arbitrary code execution. From an adversarial perspective, this vulnerability maps directly to several ATT&CK techniques including T1190 for exploitation of vulnerabilities, T1059 for command and scripting interpreter usage, and T1078 for valid accounts for persistence. The vulnerability's exploitation requires minimal technical skill and can be automated through various attack frameworks, making it particularly attractive to threat actors seeking low-hanging fruit in WordPress environments. Organizations running vulnerable versions of the WP Symposium plugin face significant risk of compromise, particularly in environments where proper security monitoring and file access controls are not implemented. The vulnerability's persistence mechanism means that once exploited, the malicious files remain accessible until manually removed, providing attackers with extended access windows.
Mitigation strategies for CVE-2011-5051 focus on immediate patching of the WP Symposium plugin to version 11.12.24 or later, which addresses the core file upload validation issues. Organizations should implement comprehensive file upload restrictions at the web server level, including the removal of executable file extensions from upload directories and the implementation of strict content type validation. Network-level monitoring should be enhanced to detect unusual file upload patterns and direct access attempts to uploaded files. Additionally, organizations should conduct thorough security assessments of their WordPress installations to identify other potentially vulnerable plugins or themes that may exhibit similar insecure file upload behaviors. Regular security updates and vulnerability scanning should be implemented as part of the overall security posture to prevent similar issues from arising in the future.