CVE-2015-5307 in VM VirtualBox
Summary
by MITRE
The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a denial of service (host OS panic or hang) by triggering many #AC (aka Alignment Check) exceptions, related to svm.c and vmx.c.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/05/2022
The vulnerability identified as CVE-2015-5307 represents a critical flaw in virtualization infrastructure that affects both the Linux kernel and Xen hypervisor implementations. This issue stems from inadequate handling of alignment check exceptions within virtual machine monitor components, specifically impacting the svm.c and vmx.c files that manage AMD and Intel virtualization technologies respectively. The vulnerability exists in versions of the Linux kernel through 4.2.6 and Xen hypervisor versions 4.3.x through 4.6.x, creating a widespread impact across numerous virtualized environments that rely on these technologies for system isolation and resource management.
The technical flaw manifests when guest operating systems exploit the alignment check exception mechanism to overwhelm host systems through excessive generation of #AC exceptions. This occurs because the virtualization subsystem fails to properly limit or handle the frequency of alignment check exceptions that can be generated by guest processes. The svm.c and vmx.c modules, which implement the virtualization extensions for AMD and Intel processors respectively, contain insufficient safeguards against malicious or malformed exception handling that could lead to resource exhaustion. When guest users trigger numerous alignment check exceptions in rapid succession, the host system becomes overwhelmed and may experience system hangs or complete kernel panics, effectively rendering the virtualization environment unusable.
The operational impact of this vulnerability extends far beyond simple denial of service, as it compromises the fundamental reliability and availability of virtualized computing environments. Organizations relying on KVM or Xen hypervisors for cloud infrastructure, containerization, or multi-tenant hosting environments face significant risks when this vulnerability exists. A malicious guest user could exploit this weakness to disrupt services across multiple virtual machines hosted on the same physical system, potentially affecting dozens or hundreds of virtual environments simultaneously. The vulnerability particularly threatens cloud service providers where multiple customers share the same underlying infrastructure, as a single compromised guest could potentially cause cascading failures throughout the entire platform. This makes the vulnerability particularly dangerous in enterprise and data center environments where virtualization is extensively utilized.
Mitigation strategies for CVE-2015-5307 require immediate patching of affected systems to address the root cause in the virtualization subsystem. Organizations should prioritize updating their Linux kernel versions to 4.3 or later and Xen hypervisor versions to 4.6.1 or higher, which contain the necessary fixes for proper exception handling. Additionally, implementing runtime monitoring and resource limiting controls can help detect and prevent excessive exception generation by guest systems. The vulnerability aligns with CWE-400, which covers "Uncontrolled Resource Consumption" and reflects the core issue of unbounded exception handling that leads to system resource exhaustion. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1499.004 for "Virtualization/Sandbox Evasion" and could be leveraged as part of broader exploitation chains targeting virtualized environments, making it a critical concern for security operations teams responsible for protecting virtual infrastructure.
The vulnerability demonstrates how low-level hardware virtualization features can create unexpected attack surfaces when not properly secured against malicious input. The alignment check exception mechanism, designed to handle memory access violations in normal operation, becomes a weapon when exploited by guest users who understand the underlying virtualization architecture. This particular flaw highlights the complexity of securing virtualized environments where multiple security domains must be properly isolated while maintaining functional performance. The impact extends beyond immediate service disruption to potentially compromise the integrity of entire virtualized platforms, making it essential for system administrators to implement comprehensive monitoring and patch management procedures to protect against such vulnerabilities that could be exploited by both insider threats and external attackers targeting virtual infrastructure.