CVE-2022-25271: Drupal Core Input Validation Vulnerability

CVE-2022-25271 Overview

CVE-2022-25271 is an Improper Input Validation vulnerability in Drupal core's form API that affects certain contributed or custom modules' forms. This flaw could allow an attacker to inject disallowed values or overwrite data through improperly validated form submissions. While affected forms are uncommon, successful exploitation could enable attackers to alter critical or sensitive data within the Drupal application.

Critical Impact

Attackers can inject disallowed values or overwrite sensitive data through vulnerable Drupal forms, potentially compromising data integrity in affected installations.

Affected Products

• Drupal Core (multiple versions)
• Fedora 35
• Fedora 36

Discovery Timeline

• 2022-02-16 - CVE-2022-25271 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-25271

Vulnerability Analysis

This vulnerability stems from improper input validation within Drupal core's form API (CWE-20). The form API is a fundamental component of Drupal that handles form rendering, validation, and submission processing. When certain contributed or custom modules implement forms that rely on the core form API without additional validation constraints, attackers may be able to bypass expected input restrictions.

The vulnerability allows remote attackers to manipulate form submissions in ways that bypass intended validation logic. This can result in the injection of values that should normally be disallowed by the application or the overwriting of existing data with malicious content. The impact is particularly concerning for forms that handle sensitive or critical data, as successful exploitation could lead to unauthorized data modification.

Root Cause

The root cause of CVE-2022-25271 lies in insufficient input validation within Drupal core's form API. The form API does not adequately validate or sanitize certain input types under specific conditions, allowing attackers to submit form data that bypasses the expected validation constraints. This affects forms implemented by contributed or custom modules that depend on the core form API for input validation rather than implementing their own additional validation logic.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no authentication or user interaction. An attacker can exploit this vulnerability by crafting malicious HTTP requests that submit specially crafted form data to vulnerable Drupal installations. The attack targets forms that rely on the core form API's validation mechanisms without implementing additional input validation controls.

The exploitation process involves:

1. Identifying a Drupal installation with vulnerable contributed or custom modules
2. Analyzing the form structure to understand expected input parameters
3. Crafting malicious form submissions with disallowed values or data designed to overwrite existing entries
4. Submitting the malicious data through standard HTTP POST requests to the vulnerable form endpoint

For technical details on the vulnerability mechanism and affected form implementations, refer to the Drupal Security Advisory SA-CORE-2022-003.

Detection Methods for CVE-2022-25271

Indicators of Compromise

• Unexpected modifications to critical data fields that should be protected from user input
• Form submission logs showing unusual or disallowed values being accepted
• Database records containing data that violates expected validation constraints
• Audit logs indicating form submissions with manipulated hidden field values

Detection Strategies

• Monitor web application logs for form submissions containing unexpected parameter values or injection patterns
• Implement Web Application Firewall (WAF) rules to detect and block requests with suspicious form data
• Review Drupal watchdog logs for form validation errors or anomalies indicating exploitation attempts
• Deploy file integrity monitoring to detect unauthorized changes to contributed module files

Monitoring Recommendations

• Enable comprehensive logging for all form submissions on sensitive Drupal forms
• Configure alerts for database modifications to critical tables that should have restricted access
• Implement real-time monitoring for unusual patterns in HTTP POST requests to form endpoints
• Regularly audit contributed and custom modules for forms that may be vulnerable to this issue

How to Mitigate CVE-2022-25271

Immediate Actions Required

• Update Drupal core to the latest patched version immediately
• Review all contributed and custom modules for forms that may be affected by improper input validation
• Audit recent form submissions for any signs of exploitation or data manipulation
• Implement additional server-side validation for forms handling sensitive data

Patch Information

Drupal has released security updates to address this vulnerability. Administrators should apply the patches documented in the Drupal Security Advisory SA-CORE-2022-003. Fedora users should apply the relevant package updates as announced in the Fedora Package Announcements.

Workarounds

• Implement additional validation in custom form handlers to verify all input values against expected constraints
• Use form alter hooks to add extra validation callbacks for sensitive forms from contributed modules
• Deploy a Web Application Firewall (WAF) with rules to filter potentially malicious form submissions
• Restrict access to sensitive forms using Drupal's permission system until patches can be applied

# Drupal update command example
drush pm:security
drush updatedb
drush cache:rebuild