CVE-2020-10100 in Zammad
Summary
by MITRE
An issue was discovered in Zammad 3.0 through 3.2. It allows for users to view ticket customer details associated with specific customers. However, the application does not properly implement access controls related to this functionality. As such, users of one company are able to access ticket data from other companies. Due to the multi-tenant nature of this application, users who can access ticket details from one organization to the next allows for users to exfiltrate potentially sensitive data of other companies.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/09/2024
This vulnerability exists within Zammad's multi-tenant architecture where improper access control implementation allows unauthorized data exposure between organizations. The flaw manifests in the ticket customer details functionality where users from one company can access ticket data belonging to other companies, representing a critical breakdown in tenant isolation. The vulnerability affects versions 3.0 through 3.2 and stems from inadequate authorization checks that should prevent cross-tenant data access. This represents a classic case of insufficient access control enforcement as classified under CWE-285, where the application fails to properly verify that users have appropriate permissions before granting access to resources. The multi-tenant nature of Zammad means that each organization operates within its own isolated environment, but the lack of proper access control boundaries creates a severe data leakage risk.
The technical implementation flaw occurs when the application processes requests for ticket customer details without validating whether the requesting user belongs to the same organization as the target customer. This allows malicious actors to exploit the system by crafting requests that bypass normal access controls, effectively enabling horizontal privilege escalation between tenants. The vulnerability operates at the application logic level where authorization decisions are made, rather than at the database or network level, making it particularly challenging to detect and prevent through traditional security controls. This type of flaw aligns with ATT&CK technique T1078.004 which covers legitimate credentials used for lateral movement, as the vulnerability enables unauthorized access using legitimate user accounts within the system.
The operational impact of this vulnerability extends beyond simple data exposure to encompass potential regulatory compliance violations and significant reputational damage for organizations using Zammad. Companies may face penalties under data protection regulations such as gdpr, hipaa, or other privacy frameworks when customer data from competing organizations is exposed. The vulnerability allows for systematic data exfiltration where attackers can collect comprehensive customer information including names, contact details, and potentially sensitive interaction data from multiple organizations. This creates a substantial risk for businesses that rely on Zammad for customer service management, as the exposure could lead to competitive intelligence gathering, identity theft, or other malicious activities. Organizations may experience cascading effects where the compromise of one tenant's data leads to further exploitation of other tenants within the same instance.
Mitigation strategies should focus on implementing robust access control mechanisms that enforce strict tenant boundaries for all ticket-related operations. Organizations should immediately upgrade to patched versions of Zammad where the access control implementation has been corrected to properly validate user permissions against tenant associations. Security measures including regular access control audits, implementation of principle of least privilege, and mandatory tenant isolation checks should be enforced. Network-level protections such as application firewalls and intrusion detection systems can help monitor for suspicious cross-tenant access patterns, while logging and monitoring should track all access to ticket customer details to detect unauthorized access attempts. The vulnerability demonstrates the critical importance of proper access control implementation in multi-tenant applications, as highlighted by CWE-693 which emphasizes the need for security controls to be properly designed and implemented to prevent unauthorized access. Organizations should also consider implementing additional security controls such as data loss prevention measures and regular security assessments to ensure that similar access control flaws do not exist in other parts of their multi-tenant infrastructure.