CVE-2023-33191 in kyverno
Summary
by MITRE • 05/30/2023
Kyverno is a policy engine designed for Kubernetes. Kyverno seccomp control can be circumvented. Users of the podSecurity `validate.podSecurity` subrule in Kyverno 1.9.2 and 1.9.3 are vulnerable. This issue was patched in version 1.9.4.
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Analysis
by VulDB Data Team • 06/21/2023
CVE-2023-33191 represents a critical security vulnerability in Kyverno, a popular policy engine for Kubernetes environments. This vulnerability specifically affects the podSecurity `validate.podSecurity` subrule functionality within Kyverno versions 1.9.2 and 1.9.3, where the seccomp control mechanisms can be bypassed by malicious actors. The flaw allows unauthorized users to circumvent security policies that are intended to enforce secure computing practices through seccomp profiles, which are essential for restricting system calls within containers. This vulnerability directly impacts the integrity of Kubernetes pod security controls and can lead to privilege escalation or unauthorized access to cluster resources. The issue stems from improper validation logic within Kyverno's policy enforcement mechanisms, where the system fails to properly verify seccomp profile configurations during pod creation or modification processes.
The technical implementation of this vulnerability involves a weakness in the validation flow of Kyverno's podSecurity policy enforcement. When users configure policies using the `validate.podSecurity` subrule, the system should enforce strict seccomp profile requirements to prevent potentially dangerous system calls from being executed within pods. However, due to the flaw in version 1.9.2 and 1.9.3, attackers can manipulate pod specifications to bypass these security controls, effectively rendering the intended security policies ineffective. This issue falls under the category of privilege escalation and policy bypass, with potential implications for container runtime security and cluster integrity. The vulnerability creates a pathway for adversaries to execute unauthorized system calls that would normally be restricted by seccomp profiles, thereby undermining the fundamental security posture of Kubernetes clusters that rely on Kyverno for policy enforcement.
The operational impact of CVE-2023-33191 extends beyond simple policy bypass scenarios, as it can enable attackers to perform lateral movement within clusters, escalate privileges, and potentially access sensitive data or system resources. Organizations using Kyverno for pod security enforcement are particularly vulnerable since the flaw affects the core functionality of security policy validation. This vulnerability aligns with CWE-284 (Improper Access Control) and CWE-345 (Insufficient Verification of Data Authenticity) categories, as it represents both access control failures and inadequate validation of policy enforcement mechanisms. The attack surface is significant for any Kubernetes environment that relies on Kyverno for pod security, particularly those implementing strict security policies that depend on seccomp profile enforcement. Additionally, this vulnerability can be leveraged as part of broader attack chains in accordance with ATT&CK framework techniques such as T1078 (Valid Accounts) and T1562.001 (Disable or Modify Tools), where attackers might use the bypass to disable security controls or establish persistent access to cluster resources.
Organizations affected by this vulnerability should immediately upgrade to Kyverno version 1.9.4 or later, which includes the necessary patches to address the seccomp control bypass issue. The remediation process should involve comprehensive testing of existing policies to ensure they function correctly after the upgrade, and security teams should conduct thorough audits of their pod security configurations. System administrators should also implement additional monitoring and logging around policy enforcement activities to detect any potential exploitation attempts. The patch addresses the root cause by implementing proper validation checks within the `validate.podSecurity` subrule, ensuring that seccomp profile requirements are properly enforced during pod lifecycle operations. Security teams should consider implementing network segmentation and additional access controls as compensating measures while upgrading their Kyverno installations to maintain cluster security posture. Regular security assessments and vulnerability scanning should be conducted to identify similar issues within the broader Kubernetes ecosystem and ensure comprehensive protection against evolving threats.