CVE-2007-6207 in Xen
Summary
by MITRE
Xen 3.x, possibly before 3.1.2, when running on IA64 systems, does not check the RID value for mov_to_rr, which allows a VTi domain to read memory of other domains.
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Analysis
by VulDB Data Team • 08/06/2019
The vulnerability identified as CVE-2007-6207 affects the Xen hypervisor version 3.x, particularly on IA64 (Itanium) architecture systems, and represents a critical security flaw in virtual machine isolation mechanisms. This issue stems from insufficient validation of the RID (Region Identifier) value during the mov_to_rr instruction execution, which is a fundamental operation in hypervisor memory management. The flaw exists in the virtualization technology implementation where the hypervisor fails to properly enforce memory access controls between different virtual machine domains, creating a potential pathway for privilege escalation and information disclosure attacks.
The technical implementation of this vulnerability occurs within the IA64 architecture's memory management unit where the mov_to_rr instruction is used to transfer data between virtual and physical memory regions. The hypervisor's failure to validate the RID value means that a malicious virtual machine running in a VTi (Virtualization Technology for Integrity) domain can manipulate this instruction to access memory regions that should be restricted to other domains. This represents a direct violation of the hypervisor's memory isolation principles, where each virtual machine domain should maintain complete separation from others to prevent unauthorized access to sensitive data. The vulnerability specifically impacts the security model of Xen hypervisor by undermining the fundamental principle that virtual machines should be isolated from one another, allowing for cross-domain memory access that violates standard security boundaries.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables a malicious domain to potentially extract sensitive data, credentials, or system information from other virtual machines running on the same physical host. This creates a significant risk for multi-tenant cloud environments where multiple customers' virtual machines share the same infrastructure, as a compromised domain could potentially access data belonging to other customers. The vulnerability's severity is amplified by the fact that it operates at the hypervisor level, meaning that the attack can bypass traditional operating system security mechanisms and directly exploit the virtualization layer itself. According to CWE classification, this vulnerability maps to CWE-284 Access Control Issues, specifically related to insufficient access control enforcement in virtualization environments.
Mitigation strategies for this vulnerability require immediate patching of the Xen hypervisor to version 3.1.2 or later, which includes proper validation of the RID value during mov_to_rr instruction execution. System administrators should also implement additional monitoring and logging of hypervisor operations to detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the hypervisor layer, and organizations should consider implementing micro-segmentation approaches to limit the potential impact of such attacks. Additionally, regular security assessments of virtualization environments and proper access control configuration should be maintained to reduce the attack surface and ensure that virtual machine domains maintain proper isolation boundaries. The vulnerability highlights the critical importance of rigorous security testing for hypervisor components and demonstrates how low-level architectural flaws can have severe consequences for entire virtualized infrastructures.