CVE-2019-6340: High Vulnerability in Drupal Core

CVE-2019-6340 is a high-severity vulnerability affecting Drupal Core, specifically in versions 8.5.x prior to 8.5.11 and 8.6.x prior to 8.6.10. This vulnerability allows for arbitrary PHP code execution due to improper sanitization of data from non-form sources. Affected systems are those with the Drupal 8 core RESTful Web Services (rest) module enabled, which permits PATCH or POST requests. Additionally, systems using other web services modules like JSON:API in Drupal 8 or Services in Drupal 7 are at risk.

The severity level is classified as high with a CVSS score of 8.1, indicating significant risk to the confidentiality, integrity, and availability of affected systems. Organizations utilizing these versions of Drupal are strongly urged to apply patches to mitigate potential exploitation.

Given the critical nature of this vulnerability, organizations should prioritize patching immediately. The potential for attackers to execute arbitrary PHP code poses a severe security risk, which can lead to unauthorized access and compromise of sensitive data.

Known exploits are available, and as of the addition of this vulnerability to the CISA known exploited vulnerabilities (KEV) catalog on March 25, 2022, organizations should be aware of the urgency to remediate.

To protect against exploitation, organizations must ensure that they are running updated versions of Drupal. Regular monitoring and security assessments can help identify and remediate such vulnerabilities proactively.

Vulnerability Details

This vulnerability allows for the execution of arbitrary PHP code in certain conditions, specifically when the RESTful Web Services module is enabled and configured incorrectly. The CVSS version is 3.1, with a vector string indicating a network attack vector and high attack complexity. Organizations running affected versions of Drupal must mitigate this risk by applying the appropriate patches.

Technical Analysis

The root cause of the vulnerability lies in improper data sanitization for some field types from non-form sources. Attackers may leverage this vulnerability by sending crafted requests that exploit the lack of sanitization, leading to arbitrary code execution. The attack vector is network-based, requiring no user interaction, and the complexity is rated as high due to the need for specific conditions to be met.

Successful exploitation may result in a complete compromise of confidentiality, integrity, and availability of the affected system. The high impact on all three fronts underscores the need for immediate action.

Risk & Impact Analysis

Risk to organizations includes unauthorized execution of PHP code, leading to potential data breaches and system compromise. The blast radius could extend to any system relying on the affected Drupal versions, making this a significant risk in environments where Drupal is deployed. Organizations should schedule remediation as a high priority to address this critical vulnerability.

Exploitation Status

Affected Versions

All versions of Drupal 8.5.x prior to 8.5.11 and versions 8.6.x prior to 8.6.10 are affected. Organizations should ensure they are using the latest version to mitigate this vulnerability.

Mitigation & Remediation

To mitigate this vulnerability, organizations should apply the latest updates from Drupal as soon as possible. For systems using the affected versions, upgrading to the latest stable release is necessary. Organizations may also consider performing configuration hardening and implementing network controls to further protect their systems.

Organizations should validate remediation through continuous penetration testing to identify similar weaknesses.

Detection Guidance

Organizations should monitor logs for unusual activity and validate that all patches have been applied. Behavioral anomalies in system performance may indicate attempts to exploit the vulnerability. Network signatures indicating unauthorized access should also be noted.

AppSecure Threat Intelligence Insight

The long-term significance of CVE-2019-6340 reflects the ongoing challenges in web application security, particularly in how services handle user input. Security teams should prioritize understanding and applying best practices in input validation and sanitization. This vulnerability serves as a reminder of the importance of maintaining security hygiene and regular updates.

Security teams should also review their vulnerability management program to ensure they can quickly identify and mitigate similar vulnerabilities in the future.

Additionally, organizations can benefit from engaging in penetration testing activities to proactively uncover weaknesses before they can be exploited.