CVE-2023-34090 in Decidim
Summary
by MITRE • 07/11/2023
Decidim is a participatory democracy framework, written in Ruby on Rails, originally developed for the Barcelona City government online and offline participation website. Decidim uses a third-party library named Ransack for filtering certain database collections (e.g., public meetings). By default, this library allows filtering on all data attributes and associations. This allows an unauthenticated remote attacker to exfiltrate non-public data from the underlying database of a Decidim instance (e.g., exfiltrating data from the user table). This issue may lead to Sensitive Data Disclosure. The problem was patched in version 0.27.3.
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Analysis
by VulDB Data Team • 07/11/2023
CVE-2023-34090 represents a critical security vulnerability within the Decidim participatory democracy framework that leverages the Ransack gem for database filtering operations. This vulnerability stems from the default configuration of Ransack which permits unrestricted filtering across all database attributes and associations without proper authorization controls. The flaw exists at the application level within the Ruby on Rails framework where Decidim implements database query construction for user-facing features such as public meetings listings. Attackers can exploit this misconfiguration to construct malicious queries that traverse database relationships and access sensitive information that should remain protected from unauthenticated users.
The technical nature of this vulnerability aligns with CWE-200, which addresses "Information Exposure," and CWE-284, which covers "Improper Access Control." The vulnerability operates through the Ransack gem's default behavior of allowing parameter-based filtering that does not properly validate or restrict access to database fields. When an attacker crafts specific HTTP requests containing filtered parameters, they can leverage the gem's functionality to perform unauthorized database queries that traverse associations and extract data from protected tables including user records. This issue particularly affects the user table where sensitive personal information, authentication details, and participation records could be exposed. The vulnerability demonstrates poor input validation and inadequate access control mechanisms within the application's data access layer.
The operational impact of CVE-2023-34090 extends beyond simple data exposure to encompass potential compromise of user privacy and system integrity. Unauthenticated remote attackers can systematically extract sensitive information from the underlying PostgreSQL or MySQL databases, potentially exposing user credentials, personal identification details, and participation history. This vulnerability directly maps to ATT&CK technique T1213.002 for "Data from Information Repositories" and T1567.002 for "Exfiltration Over Web Service" as attackers can leverage the web application interface to systematically harvest data. The exposure of user data could lead to identity theft, social engineering attacks, and compromise of the entire participatory democracy platform's credibility. Organizations relying on Decidim for civic engagement may face regulatory compliance violations under data protection laws such as GDPR or CCPA due to unauthorized data access.
Mitigation strategies for CVE-2023-34090 require immediate implementation of proper access control measures within the Ransack gem configuration. The most effective solution involves explicitly defining allowed attributes and associations for filtering operations, thereby preventing unauthorized traversal of database relationships. Organizations should implement whitelisting of permitted parameters and ensure that database queries are properly scoped to prevent information leakage. Additionally, implementing proper authentication checks before allowing any filtering operations and adding input validation layers can prevent exploitation. The patch released in Decidim version 0.27.3 addresses this issue by restricting Ransack's default behavior to only allow filtering on explicitly defined attributes. Security teams should also conduct comprehensive audits of all third-party libraries and their default configurations to prevent similar vulnerabilities, particularly those involving database query construction and filtering mechanisms. Regular security assessments and dependency updates form essential components of defending against such information disclosure vulnerabilities.