CVE-2023-29002 in Cilium
Summary
by MITRE • 04/19/2023
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. When run in debug mode, Cilium will log the contents of the `cilium-secrets` namespace. This could include data such as TLS private keys for Ingress and GatewayAPI resources. An attacker with access to debug output from the Cilium containers could use the resulting output to intercept and modify traffic to and from the affected cluster. Output of the sensitive information would occur at Cilium agent restart, when secrets in the namespace are modified, and on creation of Ingress or GatewayAPI resources. This vulnerability is fixed in Cilium releases 1.11.16, 1.12.9, and 1.13.2. Users unable to upgrade should disable debug mode.
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Analysis
by VulDB Data Team • 05/13/2023
The vulnerability identified as CVE-2023-29002 represents a critical information disclosure issue within the Cilium networking solution, which operates as an eBPF-based dataplane for containerized environments. This security flaw specifically manifests when Cilium operates in debug mode, creating an unintended exposure of sensitive cryptographic materials. The vulnerability stems from the improper handling of secret data within the cilium-secrets namespace, where cryptographic keys and certificates are logged to debug output streams without adequate sanitization or access controls. The affected Cilium agents maintain a direct relationship with ingress and gateway API resources, making the exposure particularly dangerous for clusters that rely on TLS-secured communication paths. Organizations using Cilium for network policy enforcement and service mesh capabilities face significant risk when debug mode remains enabled, as the logging mechanism becomes a vector for credential compromise.
The technical implementation of this vulnerability involves the Cilium agent's debug logging functionality which indiscriminately outputs the contents of the cilium-secrets namespace whenever specific operational events occur. These events include agent restarts, modifications to secrets within the namespace, and the creation of ingress or gateway API resources. The logging mechanism lacks proper access controls or data sanitization, allowing attackers who can access debug output streams to extract TLS private keys and other sensitive cryptographic materials. This exposure creates a direct pathway for man-in-the-middle attacks and traffic interception, as the stolen keys can be used to decrypt and modify network communications between services within the cluster. The vulnerability aligns with CWE-200 (Information Exposure) and represents a failure in proper access control implementation within the debugging subsystem. The attack surface expands significantly when considering that debug output may be accessible through standard logging mechanisms, container runtime interfaces, or cluster monitoring tools that aggregate debug information.
The operational impact of this vulnerability extends beyond simple credential theft to encompass complete network traffic compromise and potential lateral movement within the affected cluster. Attackers who gain access to the debug output can reconstruct the TLS certificate chain and private keys used for ingress and gateway API resources, enabling them to impersonate legitimate services and intercept all communications. The timing of information exposure creates multiple attack windows where an adversary can capture sensitive data during normal cluster operations, making detection challenging. This vulnerability particularly affects Kubernetes environments where Cilium serves as the primary networking solution, as it undermines the fundamental security assumptions of encrypted service-to-service communication. The risk assessment must consider the potential for privilege escalation through the use of stolen keys to access additional cluster resources, especially when these keys are used for mutual TLS authentication between services. The ATT&CK framework categorizes this as a credential access technique through information disclosure, with potential for lateral movement and privilege escalation.
Organizations should immediately disable debug mode on all Cilium agents to prevent further exposure, as this represents the most effective immediate mitigation. The vulnerability has been addressed in Cilium releases 1.11.16, 1.12.9, and 1.13.2, making upgrade the preferred long-term solution for complete remediation. Security teams must conduct comprehensive audits of their Cilium configurations to ensure debug mode is disabled in production environments and that appropriate access controls are implemented for any remaining debug output systems. The incident highlights the importance of proper configuration management and the principle of least privilege in containerized environments. Organizations should implement monitoring for debug output access and establish procedures for rapid response to potential exposure events. Additionally, the vulnerability demonstrates the critical need for secure default configurations in security tools, as leaving debug mode enabled in production environments creates unnecessary attack vectors. Regular security assessments should include verification of debug mode status and proper secret management practices to prevent similar issues in other networking and security solutions within the infrastructure stack.