CVE-2011-3147 in Nova
Summary
by MITRE
Versions of nova before 2012.1 could expose hypervisor host files to a guest operating system when processing a maliciously constructed qcow filesystem.
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Analysis
by VulDB Data Team • 09/06/2023
The vulnerability identified as CVE-2011-3147 represents a critical security flaw in the openstack nova compute service that affected versions prior to 2012.1. This issue specifically targets the qcow (qemu copy-on-write) storage format handling within the hypervisor layer, creating a potential pathway for guest operating systems to access host-level filesystem resources. The vulnerability arises from inadequate input validation and processing of maliciously constructed qcow filesystem structures that can be manipulated by unprivileged users within a virtualized environment.
The technical flaw stems from improper handling of qcow image files during the virtual machine provisioning process within the nova service. When a malicious user constructs a specially crafted qcow filesystem with malformed metadata or directory structures, the nova component fails to properly validate these inputs before passing them to the underlying hypervisor. This validation failure allows the guest operating system to potentially traverse the filesystem hierarchy and gain access to sensitive host files that should remain isolated within the hypervisor environment. The vulnerability exploits the trust relationship between the virtualization layer and the guest operating system, effectively breaking the isolation boundaries that are fundamental to virtualized computing environments.
The operational impact of CVE-2011-3147 extends beyond simple information disclosure, as it represents a serious privilege escalation vector within virtualized infrastructures. An attacker with access to a guest operating system could potentially read arbitrary files from the host system, including configuration files, credentials, and other sensitive data stored on the hypervisor. This breach of isolation could lead to complete compromise of the host system and subsequent access to all virtual machines running on that host. The vulnerability particularly affects cloud environments where multiple tenants share the same physical infrastructure, as it undermines the fundamental security assumptions of multi-tenant virtualization. From an attack perspective, this vulnerability aligns with techniques described in the attack pattern taxonomy under the category of privilege escalation and information disclosure, specifically targeting the hypervisor layer as defined in the MITRE ATT&CK framework.
Mitigation strategies for CVE-2011-3147 require immediate deployment of patched versions of nova that include proper input validation and sanitization for qcow image processing. Organizations should implement network segmentation and access controls to limit the ability of unprivileged users to construct malicious qcow images. The patch addresses the root cause by implementing strict validation of qcow filesystem structures before processing, ensuring that malformed or maliciously constructed images are rejected before they can be used in the virtualization stack. Additionally, organizations should conduct regular security assessments of their virtualization environments and implement monitoring for suspicious filesystem access patterns that could indicate exploitation attempts. This vulnerability highlights the importance of proper input validation and the principle of least privilege in virtualized environments, with remediation efforts aligning with security best practices outlined in various industry standards including those related to secure coding practices and virtualization security controls.