Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a security vulnerability in FOSSBilling, an open-source billing and client management system. The issue allows authorized users to execute arbitrary code by injecting commands into certain template systems, potentially leading to significant information disclosure and system compromise. The primary concern is confirming if our organization utilizes this system and if it is exposed.
- A flaw allows code injection through template rendering.
- Leadership should remember this if we use FOSSBilling.
- Confirm relevance and exposure for this system.
Attack Path
How an attacker could exploit the issue
Attackers with administrative privileges can exploit this vulnerability by manipulating template rendering features, such as email templates or API endpoints, to inject malicious code. This occurs because the system renders Twig templates without proper security measures, allowing unauthorized access to sensitive information and the potential for remote code execution.
- Administrator access required.
- Inject code into rendered templates.
- Leads to information disclosure, RCE.
Live Threat
Current exploitation, exposure, and threat context
Administrators with specific access could allow attackers to execute arbitrary code by injecting malicious expressions into template rendering functions. This could lead to the disclosure of sensitive system or user information due to the vulnerability existing in a system that renders Twig templates without a sandbox, enabling access to the application's full Twig environment and dependency injection container.
- Sensitive system and user data.
- Through specially crafted template inputs.
- Information disclosure and code execution.
Operational Fix
Recommended remediation, mitigation, and detection steps
System owners responsible for FOSSBilling instances must first identify all deployments, determine their exposure and criticality, and then assign remediation ownership. Given the potential for information disclosure and remote code execution, prioritizing affected systems and coordinating with the vendor or internal development teams for patching or applying workarounds is essential.
- Identify affected FOSSBilling instances.
- Verify external reachability and business impact.
- Plan remediation with responsible teams.
