CVE-2020-24948 in Autoptimize Plugin
Summary
by MITRE
The ao_ccss_import AJAX call in Autoptimize Wordpress Plugin 2.7.6 does not ensure that the file provided is a legitimate Zip file, allowing high privilege users to upload arbitrary files, such as PHP, leading to remote command execution.
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2020-24948 resides within the Autoptimize WordPress plugin version 2.7.6, specifically within the ao_ccss_import AJAX handler functionality. This flaw represents a critical security oversight that fundamentally undermines the plugin's file validation mechanisms. The issue manifests when the plugin processes compressed stylesheet files through its AJAX interface, failing to properly verify the integrity and authenticity of uploaded archives before processing them. The absence of proper zip file validation creates an exploitable condition where malicious actors can manipulate the upload process to include arbitrary file types, particularly executable PHP scripts, within what appears to be a legitimate compressed archive.
From a technical perspective, this vulnerability constitutes a classic insecure file upload flaw that aligns with CWE-434, which describes the improper restriction of uploads of executable files. The flaw occurs because the ao_ccss_import endpoint lacks proper input sanitization and file type validation procedures. High privilege users, typically administrators or editors with sufficient permissions, can leverage this vulnerability to bypass normal file upload restrictions. The plugin's failure to validate the zip file structure, compression methods, or file contents allows attackers to embed malicious PHP code within the archive, which gets extracted and executed by the server during the import process. This creates a direct path for remote code execution, as the server processes the uploaded archive without adequate verification of its contents or structure.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full system compromise. Attackers who gain access through this vector can execute arbitrary commands on the affected WordPress server, potentially leading to complete system takeover. The vulnerability's exploitation requires only a user with sufficient privileges to access the AJAX endpoint, which is often available to administrators and editors within the WordPress environment. This makes the attack surface relatively broad, as many WordPress installations maintain administrative accounts with elevated permissions that could be compromised. The remote code execution capability enables attackers to establish persistent backdoors, exfiltrate sensitive data, modify website content, or use the compromised server for further attacks against other systems.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the T1059.007 technique for command and script injection, and T1078.004 for valid accounts, since the attack exploits legitimate administrative access to execute malicious code. The vulnerability's exploitation aligns with the principle of least privilege violation, where elevated permissions are used to bypass security controls. Organizations should implement multiple layers of defense including immediate patching of the Autoptimize plugin to version 2.7.7 or later, which contains the necessary fixes for this vulnerability. Network segmentation and access controls should be reinforced to limit administrative privileges, while monitoring systems should be configured to detect unusual file upload patterns or suspicious AJAX requests. Additionally, regular security audits of WordPress plugins and themes should be conducted to identify similar vulnerabilities in other components of the web application stack, ensuring comprehensive protection against similar attack vectors that could compromise the overall security posture of the organization.