CVE-2021-29654 in AjaxSearchPro
Summary
by MITRE • 04/15/2021
AjaxSearchPro before 4.20.8 allows Deserialization of Untrusted Data (in the import database feature of the administration panel), leading to Remote Code execution.
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Analysis
by VulDB Data Team • 04/21/2021
The vulnerability identified as CVE-2021-29654 affects the AjaxSearchPro plugin version 4.20.8 and earlier, presenting a critical security risk through deserialization of untrusted data within the import database feature of the administration panel. This flaw resides in the plugin's handling of user-supplied input during database import operations, creating a pathway for remote code execution attacks that can compromise entire WordPress installations. The vulnerability specifically manifests when administrators interact with the plugin's administrative interface to import database content, where maliciously crafted serialized data can be processed without adequate sanitization or validation.
The technical exploitation of this vulnerability leverages the principle of object deserialization, where PHP's unserialize() function processes serialized data structures that should remain trusted and secure. When an attacker can manipulate the serialized input during the import process, they can inject malicious objects that execute arbitrary code on the target server with the privileges of the web application. This deserialization flaw represents a well-documented weakness classified under CWE-502, which specifically addresses "Deserialization of Untrusted Data" as a critical security concern in software applications. The vulnerability enables attackers to bypass typical security controls and execute commands directly on the server, potentially leading to full system compromise.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the compromised system and enables them to establish backdoors, exfiltrate sensitive data, or deploy additional malware. The remote code execution capability means that attackers do not require physical access or prior authentication to exploit the vulnerability, making it particularly dangerous in web environments where the administrative interface is accessible. The attack surface is further expanded because the vulnerability exists within a plugin that many WordPress sites utilize, creating a widespread potential impact across numerous installations. This vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1078.004 for "Valid Accounts: Cloud Accounts," as attackers can leverage the compromised system to maintain persistence and escalate privileges within cloud environments.
Mitigation strategies for CVE-2021-29654 require immediate action to upgrade the AjaxSearchPro plugin to version 4.20.8 or later, which contains the necessary patches to address the deserialization vulnerability. Organizations should implement comprehensive input validation and sanitization measures for all user-supplied data, particularly within administrative interfaces where import functions are available. Security monitoring should be enhanced to detect unusual patterns in database import activities, and access controls should be tightened for administrative functions to limit the attack surface. The implementation of web application firewalls and security headers can provide additional defense-in-depth measures, while regular security audits and penetration testing should verify the effectiveness of these mitigations. System administrators should also consider implementing principle of least privilege access controls and regularly review user permissions to minimize potential damage from successful exploitation attempts.