CVE-2012-3498 in XenServer
Summary
by MITRE
PHYSDEVOP_map_pirq in Xen 4.1 and 4.2 and Citrix XenServer 6.0.2 and earlier allows local HVM guest OS kernels to cause a denial of service (host crash) and possibly read hypervisor or guest memory via vectors related to a missing range check of map->index.
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Analysis
by VulDB Data Team • 04/12/2021
The vulnerability identified as CVE-2012-3498 resides within the Xen hypervisor implementation specifically affecting versions 4.1 and 4.2 along with Citrix XenServer 6.0.2 and earlier releases. This issue manifests in the PHYSDEVOP_map_pirq function which handles physical device interrupt routing operations within the hypervisor environment. The flaw represents a critical security weakness that enables malicious local HVM (Hardware Virtual Machine) guest operating systems to exploit a missing range check in the map->index parameter processing, creating a pathway for unauthorized system compromise.
The technical implementation of this vulnerability stems from inadequate input validation within the hypervisor's physical device interrupt mapping subsystem. When a guest OS kernel attempts to map physical interrupts through the PHYSDEVOP_map_pirq operation, the hypervisor fails to properly validate the index range provided by the guest. This missing range check creates a condition where malicious inputs can cause memory access violations or buffer overflows within the hypervisor's memory management structures. The vulnerability specifically targets the map->index field which controls interrupt mapping operations, allowing attackers to manipulate memory addresses beyond the intended boundaries.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable memory disclosure attacks against both the hypervisor and other guest operating systems. Local HVM guest kernels can leverage this flaw to crash the host system entirely, disrupting all virtualized environments running on that hypervisor instance. Additionally, the vulnerability may allow for information disclosure through memory reads, potentially exposing sensitive hypervisor data structures, guest memory contents, or other confidential information that could be leveraged for further exploitation. This represents a significant threat to the security isolation properties that hypervisors are designed to maintain between different virtual environments.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-129 Input Validation and CWE-787 Out-of-bounds Write, both of which are categorized under the Common Weakness Enumeration taxonomy. The attack pattern aligns with ATT&CK techniques involving privilege escalation and information gathering, specifically targeting the hypervisor layer to compromise the entire virtualization infrastructure. The vulnerability demonstrates how flaws in hypervisor code can create attack vectors that bypass traditional guest OS security measures, making it particularly dangerous in multi-tenant cloud environments where isolation between different customers' virtual machines is paramount.
Mitigation strategies for CVE-2012-3498 require immediate patching of affected Xen hypervisor versions to implement proper range validation for the map->index parameter. Organizations should prioritize updating their Xen hypervisor installations to versions that include the patched PHYSDEVOP_map_pirq implementation with appropriate input validation. System administrators should also implement monitoring for unusual interrupt mapping operations and consider implementing additional hypervisor security modules that can detect and prevent malformed interrupt mapping requests. The vulnerability underscores the importance of maintaining up-to-date virtualization infrastructure and highlights the critical need for rigorous input validation in hypervisor code to prevent local privilege escalation attacks that could compromise entire virtualization platforms.