CVE-2017-16871 in UpdraftPlus Plugin
Summary
by MITRE
The UpdraftPlus plugin through 1.13.12 for WordPress allows remote PHP code execution because the plupload_action function in /wp-content/plugins/updraftplus/admin.php has a race condition before deleting a file associated with the name parameter.
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Analysis
by VulDB Data Team • 08/06/2024
The vulnerability identified as CVE-2017-16871 represents a critical remote code execution flaw within the UpdraftPlus WordPress plugin ecosystem. This vulnerability exists in versions up to and including 1.13.12, making it a widespread concern for WordPress administrators who rely on this popular backup solution. The flaw stems from a race condition in the plupload_action function located within the admin.php file of the plugin, creating a window of opportunity for malicious actors to exploit the system. The race condition occurs during the file handling process where the plugin processes uploaded files associated with the name parameter, leaving a temporal gap that attackers can manipulate for unauthorized code execution.
The technical implementation of this vulnerability involves the plugin's handling of file uploads and subsequent deletion operations within the WordPress admin interface. When users upload files through the UpdraftPlus plugin, the system processes these uploads through the plupload_action function which fails to properly synchronize file operations. This race condition allows attackers to exploit the timing gap between when a file is uploaded and when it is deleted or processed, enabling them to inject and execute arbitrary PHP code on the target server. The vulnerability specifically targets the name parameter handling, where the system does not adequately validate or sanitize the file names before processing them through the file management functions.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to fully compromise WordPress installations that utilize affected versions of UpdraftPlus. Successful exploitation can lead to complete server takeover, data exfiltration, and the potential for establishing persistent backdoors within the compromised environment. The vulnerability affects not only individual websites but also poses significant risks to WordPress multisite installations where multiple sites share the same vulnerable plugin. This type of vulnerability directly aligns with CWE-367, which describes the weakness of Time-of-Check to Time-of-Use (TOCTOU) race conditions, and represents a classic example of how improper synchronization in file operations can lead to privilege escalation and code execution.
Mitigation strategies for CVE-2017-16871 require immediate action from WordPress administrators, including updating to the patched version of UpdraftPlus or implementing temporary workarounds to prevent file upload functionality until the update is applied. Organizations should also implement network-based detection measures to monitor for suspicious file upload activities and unauthorized code execution attempts. The ATT&CK framework categorizes this vulnerability under T1059.007 for PHP execution and T1078 for valid accounts, as attackers can leverage this vulnerability to establish persistent access. Security teams should conduct comprehensive audits of all WordPress installations to identify vulnerable plugin versions and ensure proper patch management procedures are in place. Additionally, implementing web application firewalls and monitoring for unusual file upload patterns can provide early detection capabilities against exploitation attempts. The vulnerability underscores the importance of proper input validation and file handling procedures in web applications, particularly in administrative interfaces where file operations are common.