CVE-2019-6339 in Drupal
Summary
by MITRE
In Drupal Core versions 7.x prior to 7.62, 8.6.x prior to 8.6.6 and 8.5.x prior to 8.5.9; A remote code execution vulnerability exists in PHP's built-in phar stream wrapper when performing file operations on an untrusted phar:// URI. Some Drupal code (core, contrib, and custom) may be performing file operations on insufficiently validated user input, thereby being exposed to this vulnerability. This vulnerability is mitigated by the fact that such code paths typically require access to an administrative permission or an atypical configuration.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/02/2023
The vulnerability described in CVE-2019-6339 represents a critical remote code execution flaw affecting multiple versions of the Drupal content management system. This vulnerability stems from a fundamental issue within PHP's phar stream wrapper implementation, specifically when processing untrusted phar:// URIs during file operations. The flaw exists in the core PHP functionality rather than being exclusively a Drupal-specific issue, making it particularly dangerous as it can be exploited across various PHP applications that utilize the phar stream wrapper. The vulnerability affects Drupal core versions 7.x before 7.62, 8.6.x before 8.6.6, and 8.5.x before 8.5.9, indicating that this was a widespread concern affecting the majority of Drupal 7 and 8 installations during the affected period.
The technical exploitation of this vulnerability occurs when Drupal code performs file operations on user-provided input that has not been adequately validated. This includes scenarios where the system processes file paths or URLs that may contain phar:// protocol references. When PHP's phar stream wrapper encounters an untrusted phar URI, it can execute arbitrary code during the file operation, allowing attackers to bypass normal security restrictions and execute malicious payloads on the affected system. This vulnerability is categorized under CWE-470 as "Use of Externally-Controlled Input in Expression" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Python" and T1059.008 for "Command and Scripting Interpreter: PowerShell" in the context of code execution through file operations. The exploitation typically requires a specific code path that allows for file operations on user input, which is why the vulnerability is considered mitigated by the requirement for administrative access or unusual system configurations.
The operational impact of this vulnerability is severe and potentially devastating for affected organizations. Successful exploitation can result in complete system compromise, allowing attackers to execute arbitrary commands with the privileges of the web server process. This could lead to data breaches, system infiltration, and the deployment of additional malicious software. The vulnerability's impact extends beyond simple code execution to include potential privilege escalation and persistence mechanisms. Organizations running affected Drupal versions face significant risk of unauthorized access to their web applications and underlying infrastructure. The vulnerability's presence in core Drupal functionality means that even well-configured systems could be compromised if they have any code paths that process untrusted input through file operations. This makes the vulnerability particularly dangerous because it can be exploited through various attack vectors including user input forms, file uploads, or any mechanism that allows external input to influence file system operations.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Drupal installations to the recommended versions that contain the security fixes. Organizations should also implement network-level restrictions to prevent unauthorized access to administrative interfaces and implement proper input validation for all user-provided data. The principle of least privilege should be enforced by ensuring that web server processes run with minimal required permissions and that administrative access is protected through multi-factor authentication. Security monitoring should be enhanced to detect unusual file operations or access patterns that might indicate exploitation attempts. Additionally, organizations should consider implementing web application firewalls and content security policies to further reduce the attack surface. The vulnerability's classification under CWE-470 and its alignment with ATT&CK techniques emphasize the importance of input validation and secure coding practices throughout the application lifecycle. Regular security audits and vulnerability assessments should be conducted to identify similar issues in custom modules and contributed projects that might be susceptible to similar exploitation patterns.