CVE-2012-5512 in Xen
Summary
by MITRE
Array index error in the HVMOP_set_mem_access handler in Xen 4.1 allows local HVM guest OS administrators to cause a denial of service (crash) or obtain sensitive information via unspecified vectors.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-5512 represents a critical array index error within the Hardware Virtual Machine operational handler of the Xen hypervisor version 4.1. This flaw exists in the HVMOP_set_mem_access function which manages memory access permissions for guest operating systems. The vulnerability specifically affects local administrators within HVM (Hardware Virtual Machine) guest environments who possess sufficient privileges to manipulate memory access settings. The issue stems from inadequate bounds checking in the memory management handler that processes requests to modify memory access permissions, creating a scenario where malicious input can cause the hypervisor to access memory locations outside the intended array boundaries.
The technical nature of this vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a classic buffer over-read condition that can lead to system instability. When a malicious HVM guest administrator issues a crafted request through the HVMOP_set_mem_access operation, the hypervisor fails to properly validate the input parameters before using them as array indices. This oversight allows the attacker to potentially trigger memory corruption that manifests as either a system crash or information disclosure. The vulnerability's impact is particularly concerning because it operates at the hypervisor level where guest administrators already possess elevated privileges, making it a significant concern for virtualized environments where multiple tenants share the same physical infrastructure.
From an operational perspective, this vulnerability creates a potential denial of service scenario where a compromised or malicious guest operating system could crash the entire hypervisor instance, affecting all virtual machines running on that host. Additionally, the information disclosure aspect means that attackers could potentially extract sensitive data from the hypervisor's memory space, including guest memory contents or hypervisor internal structures. The attack vector is particularly dangerous in multi-tenant cloud environments where guest administrators might attempt to exploit this vulnerability to either disrupt services or gain unauthorized access to other virtual machines. The vulnerability's classification under the ATT&CK framework would fall within the privilege escalation and defense evasion categories, as it enables local administrators to potentially escalate their privileges or bypass security controls.
The mitigation strategy for CVE-2012-5512 requires immediate patching of affected Xen hypervisor versions to the latest stable releases that contain the necessary bounds checking fixes. Organizations should also implement monitoring for unusual memory access patterns and unauthorized modifications to memory permissions within virtualized environments. Network segmentation and hypervisor hardening measures can help reduce the potential impact of such vulnerabilities, while regular security audits of virtualization environments should include checks for similar memory management flaws. The vulnerability highlights the critical importance of thorough input validation in hypervisor code, particularly in functions that handle guest-to-hypervisor communication where privilege levels are elevated. System administrators should also consider implementing additional logging and alerting mechanisms around hypervisor memory management operations to detect potential exploitation attempts.