CVE-2013-4355 in Xen
Summary
by MITRE
Xen 4.3.x and earlier does not properly handle certain errors, which allows local HVM guests to obtain hypervisor stack memory via a (1) port or (2) memory mapped I/O write or (3) other unspecified operations related to addresses without associated memory.
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Analysis
by VulDB Data Team • 05/26/2021
The vulnerability identified as CVE-2013-4355 affects Xen hypervisor versions 4.3.x and earlier, representing a critical security flaw that enables local HVM (Hardware Virtual Machine) guests to access hypervisor stack memory through improper error handling mechanisms. This issue stems from insufficient validation of memory operations within the hypervisor's virtualization layer, creating a pathway for malicious guest operating systems to extract sensitive data from the host system's memory space. The vulnerability specifically manifests when the hypervisor fails to properly manage error conditions associated with port I/O operations, memory mapped I/O writes, and unspecified address operations that lack proper memory associations.
The technical exploitation of this vulnerability occurs through three primary vectors that all share the common weakness of inadequate error handling within the hypervisor's memory management subsystem. When HVM guests perform port I/O operations, memory mapped I/O writes, or other memory operations on addresses without associated memory mappings, the hypervisor's error handling routines fail to prevent access to the underlying hypervisor stack memory. This allows attackers to potentially read sensitive information including cryptographic keys, virtual machine configurations, and other confidential data stored in the hypervisor's memory space. The flaw represents a classic case of improper input validation and error state management that violates fundamental security principles of isolation between virtual machines and the host system.
The operational impact of CVE-2013-4355 extends beyond simple information disclosure, as the ability to access hypervisor stack memory could potentially enable more sophisticated attacks including privilege escalation and hypervisor compromise. Attackers with local access to HVM guests could leverage this vulnerability to extract confidential information from the hypervisor's memory, potentially gaining access to other virtual machines running on the same host system. This creates a significant risk for cloud environments and virtualized infrastructure where multiple tenants share the same physical hardware, as the vulnerability could be exploited to break isolation boundaries between virtual machines. The vulnerability's classification aligns with CWE-200 (Information Exposure) and CWE-248 (Uncaught Exception) in the Common Weakness Enumeration catalog, reflecting the improper handling of exceptional conditions that leads to unintended information disclosure.
Mitigation strategies for this vulnerability primarily focus on immediate remediation through Xen hypervisor version upgrades to 4.4.0 or later, which contain the necessary patches to address the improper error handling mechanisms. Organizations should also implement network segmentation and access controls to limit local guest access where possible, though this provides only partial protection given that the vulnerability requires local guest execution to exploit. Additional defensive measures include monitoring for suspicious I/O operations and implementing hypervisor hardening practices that reduce the attack surface. From an ATT&CK framework perspective, this vulnerability maps to T1059 (Command and Scripting Interpreter) and T1003 (OS Credential Dumping) as potential exploitation techniques, though the initial access vector remains local guest execution. The vulnerability demonstrates the critical importance of proper error handling in security-sensitive systems and underscores the need for comprehensive testing of error conditions in virtualization environments.