CVE-2017-6381 in Drupal
Summary
by MITRE
A 3rd party development library including with Drupal 8 development dependencies is vulnerable to remote code execution. This is mitigated by the default .htaccess protection against PHP execution, and the fact that Composer development dependencies aren't normal installed. You might be vulnerable to this if you are running a version of Drupal before 8.2.2. To be sure you aren't vulnerable, you can remove the <siteroot>/vendor/phpunit directory from your production deployments
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Analysis
by VulDB Data Team • 12/30/2019
The vulnerability described in CVE-2017-6381 represents a critical remote code execution flaw originating from a third-party development library bundled with Drupal 8. This issue specifically affects the PHPUnit testing framework dependency that was included in Drupal 8 development environments. The vulnerability stems from the improper handling of file execution within the development dependencies, creating an attack vector that could allow malicious actors to execute arbitrary code on affected systems. The flaw exists because the development dependencies, which are not typically deployed in production environments, contain code that could be exploited if improperly configured or if the default security protections are bypassed.
The technical nature of this vulnerability aligns with CWE-434, which addresses insecure file upload and execution scenarios. The flaw manifests when development dependencies containing PHP code are accessible in production environments, typically through misconfigured web server settings or improper deployment procedures. The default .htaccess protection mechanisms built into Drupal 8 provide a crucial layer of defense by restricting PHP execution in sensitive directories, but this protection is only effective when properly configured and maintained. The vulnerability's exploitation requires that the attacker either bypasses the default security restrictions or that the development dependencies are improperly installed in production environments where they should not exist.
The operational impact of this vulnerability extends beyond simple code execution, as it could enable attackers to gain full control over affected Drupal installations. This represents a significant threat to web application security, particularly for organizations running older versions of Drupal 8 where the vulnerability remains unpatched. The risk is particularly elevated for systems that have been manually configured to include development dependencies in production deployments, or those that have not properly removed the vendor directories during deployment processes. Attackers could leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or compromise entire web application infrastructures.
The recommended mitigation strategies focus on proper deployment hygiene and security configuration practices. The primary defense involves removing the vendor/phpunit directory from production deployments, which directly addresses the root cause by eliminating the vulnerable code from the operational environment. This approach aligns with the principle of least privilege and defense in depth, ensuring that only necessary code remains in production systems. Organizations should also ensure that their .htaccess configurations remain intact and properly secured, as these files provide essential protection against unauthorized PHP execution. Additionally, the vulnerability highlights the importance of maintaining current Drupal versions, specifically recommending updates to Drupal 8.2.2 or later, which contain patches addressing this specific security issue. The remediation process should include comprehensive security audits to verify that no development dependencies remain in production environments, and regular monitoring to prevent accidental reintroduction of vulnerable code. This vulnerability serves as a reminder of the critical importance of proper security configuration management and the dangers of including development tools in production deployments, particularly in environments where security controls may be bypassed or weakened.