CVE-2023-34058 in Tools
Summary
by MITRE • 10/27/2023
VMware Tools contains a SAML token signature bypass vulnerability. A malicious actor that has been granted Guest Operation Privileges https://docs.vmware.com/en/VMware-vSphere/8.0/vsphere-security/GUID-6A952214-0E5E-4CCF-9D2A-90948FF643EC.html in a target virtual machine may be able to elevate their privileges if that target virtual machine has been assigned a more privileged Guest Alias https://vdc-download.vmware.com/vmwb-repository/dcr-public/d1902b0e-d479-46bf-8ac9-cee0e31e8ec0/07ce8dbd-db48-4261-9b8f-c6d3ad8ba472/vim.vm.guest.AliasManager.html .
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Analysis
by VulDB Data Team • 11/21/2025
This vulnerability resides within VMware Tools and represents a critical privilege escalation flaw that exploits the SAML token signature verification mechanism. The vulnerability allows malicious actors who already possess Guest Operation Privileges to bypass security controls and elevate their access level when the target virtual machine has been configured with a more privileged Guest Alias. This creates a dangerous scenario where limited guest access can be leveraged to achieve higher privileges through improper token validation. The flaw specifically targets the authentication flow within VMware's guest operating system integration components, where SAML tokens are used to verify guest identity and access permissions. The vulnerability demonstrates a fundamental weakness in the token signature validation process, allowing attackers to manipulate or bypass the security checks that should prevent privilege escalation.
The technical implementation of this vulnerability involves the manipulation of SAML token signatures within the VMware Tools framework, specifically when guest operations are performed on virtual machines that have been assigned elevated guest aliases. When a guest user with limited privileges attempts operations on a VM with a privileged alias, the system should validate that the user has proper authorization to perform such actions. However, due to the signature bypass flaw, malicious actors can craft or manipulate SAML tokens that appear valid to the system while actually granting unauthorized elevated privileges. This represents a failure in the principle of least privilege enforcement and demonstrates a critical gap in the authentication and authorization mechanisms. The vulnerability is particularly concerning because it operates at the guest operating system level within virtualized environments, making it difficult to detect and monitor through traditional network-based security controls.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially compromise entire virtualized environments. Attackers who successfully exploit this flaw can gain access to resources that should be restricted to privileged users, potentially leading to data exfiltration, system manipulation, or further lateral movement within the virtual infrastructure. The vulnerability affects VMware vSphere environments where guest operations are enabled and guest aliases are configured with elevated privileges, creating a significant risk for organizations that rely heavily on virtualized computing environments. Organizations using VMware Tools for guest operating system integration are particularly vulnerable, as this flaw can be exploited from within the guest operating system itself. The attack vector is particularly insidious because it requires minimal initial access - only guest operation privileges are needed to begin the exploitation process, which are often granted to legitimate users for operational purposes.
Mitigation strategies for this vulnerability should focus on immediate patching of affected VMware Tools installations and careful review of guest alias configurations within virtual environments. Organizations should implement strict access controls and regularly audit guest operation privileges to ensure that only necessary users have access to guest operations. The principle of least privilege should be enforced more rigorously, particularly for guest aliases that have elevated permissions. Network segmentation and monitoring of guest operations can help detect anomalous behavior that might indicate exploitation attempts. Additionally, organizations should consider implementing multi-factor authentication for guest operations and regularly review access controls to ensure that guest aliases are properly configured with appropriate privilege levels. This vulnerability highlights the importance of proper authentication flow validation and the need for robust signature verification mechanisms in virtualized environments, aligning with CWE-347 standards for secure authentication and the ATT&CK technique T1078 for valid accounts.