CVE-2020-28346 in ACRN
Summary
by MITRE • 03/26/2021
ACRN through 2.2 has a devicemodel/hw/pci/virtio/virtio.c NULL Pointer Dereference.
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Analysis
by VulDB Data Team • 04/05/2021
The vulnerability identified as CVE-2020-28346 represents a critical null pointer dereference flaw within the ACRN hypervisor version 2.2 and earlier releases. This issue resides in the devicemodel/hw/pci/virtio/virtio.c source file, which forms a fundamental component of the hypervisor's virtualization infrastructure. The ACRN hypervisor, designed for embedded systems and IoT environments, implements virtualization capabilities to support multiple operating systems on a single physical platform. This particular vulnerability occurs within the virtio device implementation that handles communication between guest operating systems and virtualized hardware components through the PCI bus interface.
The technical flaw manifests when the virtio subsystem processes certain malformed or unexpected input data structures during device initialization or operation. Specifically, the code fails to properly validate pointer references before dereferencing them, creating a scenario where a null pointer is accessed when the system expects a valid memory reference. This condition typically occurs in the context of PCI configuration space handling or virtio device state management, where the hypervisor attempts to access device configuration parameters without ensuring proper initialization of the referenced structures. The vulnerability is categorized under CWE-476 as a NULL Pointer Dereference, which represents a well-known class of software defects that can lead to system crashes or potentially exploitable conditions.
The operational impact of this vulnerability extends beyond simple system instability, as it can be leveraged by malicious actors to cause denial of service attacks against virtualized environments. When exploited, the null pointer dereference results in immediate system crashes or kernel panics, effectively terminating the virtualization session and potentially compromising the underlying physical host system. In embedded and IoT deployments where ACRN hypervisors are commonly deployed, such vulnerabilities can have severe consequences as they may disrupt critical infrastructure services or industrial control systems. The vulnerability affects all ACRN versions up to and including 2.2, indicating that a significant portion of the deployed hypervisor ecosystem could be impacted by this flaw.
Mitigation strategies for CVE-2020-28346 primarily involve upgrading to ACRN version 2.3 or later, where the null pointer dereference has been addressed through proper input validation and pointer checking mechanisms. System administrators should also implement monitoring solutions to detect anomalous behavior that might indicate exploitation attempts, particularly in environments where guest operating systems have elevated privileges. The fix typically involves adding null checks before pointer dereference operations and implementing proper error handling for edge cases in device configuration processing. Organizations should also consider implementing additional security controls such as hypervisor hardening, network segmentation, and access control measures to reduce the potential attack surface. This vulnerability aligns with ATT&CK technique T1059.001 for command and script injection, as exploitation could potentially lead to privilege escalation or system compromise. The remediation process should include thorough testing of upgraded systems to ensure compatibility with existing virtualized workloads while maintaining the security improvements.