CVE-2022-35867 in xhyve
Summary
by MITRE • 08/03/2022
This vulnerability allows local attackers to escalate privileges on affected installations of xhyve. An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the e1000 virtual device. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a stack-based buffer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the hypervisor. Was ZDI-CAN-15056.
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Analysis
by VulDB Data Team • 08/04/2022
The vulnerability identified as CVE-2022-35867 represents a critical privilege escalation flaw within the xhyve hypervisor implementation, specifically affecting systems that utilize the e1000 virtual network device. This issue resides in the virtualized network interface driver component that handles network packet processing and transmission within the guest operating system environment. The vulnerability stems from inadequate input validation mechanisms within the e1000 device emulation layer, creating a potential pathway for malicious actors to gain elevated system privileges. The flaw manifests when the hypervisor processes network data packets that contain malformed length indicators, leading to improper buffer handling and subsequent memory corruption. This particular vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when data exceeding the allocated buffer space is copied to a stack-based memory location without proper bounds checking. The attack vector requires an initial foothold within the guest system, as local attackers must first establish execution privileges in the guest environment before leveraging this privilege escalation mechanism. The exploitation process involves crafting specially formatted network packets that trigger the buffer overflow condition, ultimately allowing the attacker to execute arbitrary code with hypervisor-level privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security isolation that hypervisors are designed to maintain between guest operating systems and the underlying host system. When successfully exploited, the vulnerability enables attackers to bypass the hypervisor's security boundaries and execute malicious code with the highest level of system privileges available to the hypervisor process. This creates a severe threat landscape where an attacker could potentially access, modify, or exfiltrate data from other virtual machines running on the same host system, effectively nullifying the security benefits of virtualization. The vulnerability affects systems that implement xhyve as their hypervisor solution, particularly those utilizing the e1000 network adapter emulation for virtualized network connectivity. The exploitation requires careful crafting of network traffic that can trigger the specific buffer overflow condition within the e1000 device driver implementation. This vulnerability aligns with ATT&CK technique T1055.001 for privilege escalation through the exploitation of software vulnerabilities, specifically targeting hypervisor-level processes. The impact is particularly severe because the hypervisor operates with the highest privileges on the host system, making successful exploitation equivalent to gaining complete control over the underlying hardware infrastructure.
Mitigation strategies for CVE-2022-35867 must address both immediate remediation and long-term architectural considerations to prevent exploitation attempts. The primary recommendation involves applying the vendor-provided security patches that implement proper input validation and bounds checking for user-supplied data within the e1000 device emulation layer. Organizations should also consider implementing network segmentation and access controls to limit the ability of attackers to establish execution privileges within guest systems, thereby preventing the initial exploitation prerequisite. Additional defensive measures include monitoring for anomalous network traffic patterns that could indicate exploitation attempts, particularly around the specific buffer overflow conditions that trigger this vulnerability. Security teams should implement network-based intrusion detection systems that can identify and block malicious network packets designed to exploit this specific vulnerability. The mitigation approach should also incorporate regular vulnerability assessments and penetration testing to identify similar weaknesses in the virtualization stack. Organizations using xhyve hypervisors should consider upgrading to newer versions that have addressed this specific buffer overflow issue, as well as implementing hypervisor hardening measures that reduce the attack surface available to potential exploiters. The vulnerability demonstrates the critical importance of validating all input data within virtualized environments, as even seemingly benign network traffic can be weaponized to compromise the entire virtualization infrastructure when proper validation mechanisms are absent.