CVE-2017-4925 in ESXi
Summary
by MITRE
VMware ESXi 6.5 without patch ESXi650-201707101-SG, ESXi 6.0 without patch ESXi600-201706101-SG, ESXi 5.5 without patch ESXi550-201709101-SG, Workstation (12.x before 12.5.3), Fusion (8.x before 8.5.4) contain a NULL pointer dereference vulnerability. This issue occurs when handling guest RPC requests. Successful exploitation of this issue may allow attackers with normal user privileges to crash their VMs.
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Analysis
by VulDB Data Team • 01/13/2021
The vulnerability identified as CVE-2017-4925 represents a critical NULL pointer dereference flaw affecting multiple VMware virtualization platforms including ESXi versions 5.5, 6.0, and 6.5, as well as Workstation and Fusion products. This vulnerability stems from inadequate input validation within the remote procedure call handling mechanism of VMware's virtualization infrastructure, specifically when processing guest RPC requests. The flaw manifests as a failure to properly validate pointer references during RPC processing, leading to potential system crashes when malformed or unexpected RPC data is received from guest operating systems. The vulnerability is classified under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a well-documented and dangerous class of software defects that can lead to denial of service and system instability.
The operational impact of this vulnerability extends beyond simple system crashes, as it provides attackers with a mechanism to disrupt virtual machine operations without requiring elevated privileges. Attackers with normal user access within a guest operating system can exploit this vulnerability to cause their own virtual machine to crash, potentially leading to data loss, service interruption, and denial of service conditions for legitimate users. The vulnerability affects the core virtualization functionality by targeting the RPC handling layer that facilitates communication between guest operating systems and the hypervisor, creating a pathway for malicious actors to compromise system stability. This issue aligns with ATT&CK technique T1499 which covers network denial of service attacks, and represents a specific exploitation vector that leverages the inherent trust relationships within virtualized environments.
Mitigation strategies for CVE-2017-4925 require immediate implementation of vendor-provided patches including ESXi650-201707101-SG for ESXi 6.5 systems, ESXi600-201706101-SG for ESXi 6.0 systems, and ESXi550-201709101-SG for ESXi 5.5 systems. Additionally, users of VMware Workstation and Fusion must upgrade to versions 12.5.3 and 8.5.4 respectively to address the vulnerability in their respective products. Beyond patch management, organizations should implement network segmentation to limit guest-to-host communication where possible, and establish monitoring protocols to detect unusual VM crash patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and memory management in hypervisor components, as highlighted by the CWE-476 classification which emphasizes the need for robust pointer validation mechanisms. Security teams should also consider implementing virtual machine isolation measures and regular vulnerability assessments to identify similar weaknesses in their virtualization environments, particularly focusing on RPC and inter-VM communication channels that may present similar attack surfaces.