CVE-2023-20900
📋 TL;DR
This CVE describes a privilege escalation vulnerability in VMware vSphere where a malicious actor with Guest Operation Privileges in a target virtual machine can elevate their privileges if that VM has been assigned a more privileged Guest Alias. This affects VMware vSphere environments where Guest Alias functionality is configured.
💻 Affected Systems
- VMware vSphere
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
Ontap Select Deploy Administration Utility by Netapp
View all CVEs affecting Ontap Select Deploy Administration Utility →
Tools by Vmware
Tools by Vmware
⚠️ Risk & Real-World Impact
Worst Case
An attacker with Guest Operation Privileges could gain full administrative control over the virtual machine, potentially leading to lateral movement, data exfiltration, or complete compromise of the virtualized environment.
Likely Case
Privileged users or compromised accounts with Guest Operation Privileges could escalate to higher privileges within the virtual machine, enabling unauthorized access to sensitive data or system resources.
If Mitigated
With proper access controls and minimal privilege assignments, the attack surface is reduced, limiting the impact to isolated virtual machines without critical data.
🎯 Exploit Status
Exploitation requires existing Guest Operation Privileges and knowledge of Guest Alias configurations. No public exploit code has been identified in the provided references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check VMware Security Advisory VMSA-2023-0020 for specific patched versions
Vendor Advisory: https://www.vmware.com/security/advisories/VMSA-2023-0020.html
Restart Required: Yes
Instructions:
1. Review VMware Security Advisory VMSA-2023-0020. 2. Identify affected vSphere versions. 3. Apply the appropriate patch from VMware. 4. Restart affected virtual machines and vSphere services.
🔧 Temporary Workarounds
Restrict Guest Operation Privileges
allLimit Guest Operation Privileges to only necessary users and virtual machines
# Review and modify vSphere permissions through vCenter Server GUI or PowerCLI
# Example PowerCLI to check permissions: Get-VIPermission -Entity <VM> | Where {$_.Role -like '*GuestOps*'}
Review Guest Alias Assignments
allAudit and remove unnecessary privileged Guest Alias assignments
# Use vSphere Client to review Guest Alias configurations
# Navigate to VM > Configure > VM Options > Advanced > Configuration Parameters
🧯 If You Can't Patch
- Implement strict access controls: Only grant Guest Operation Privileges to trusted administrators and limit to specific virtual machines.
- Regularly audit Guest Alias configurations: Ensure no virtual machines have unnecessary privileged Guest Alias assignments.
🔍 How to Verify
Check if Vulnerable:
Check vSphere version against VMware Security Advisory VMSA-2023-0020. Review if Guest Operation Privileges are granted and Guest Alias with higher privileges is configured.Check Version:
# From vSphere CLI: vmware -v
# From ESXi host: esxcli system version getVerify Fix Applied:
Verify vSphere version is updated to patched version listed in VMSA-2023-0020. Confirm Guest Alias configurations follow principle of least privilege.📡 Detection & Monitoring
Log Indicators:
- Unusual Guest Operation activities from non-privileged users
- Failed privilege escalation attempts in guest OS logs
- Changes to Guest Alias configurations
Network Indicators:
- Unusual vSphere API calls related to Guest Operations
- Suspicious authentication patterns to vSphere management interfaces
SIEM Query:
source="vsphere" AND (event_type="GuestOps" OR event_type="AliasManager") AND user NOT IN ["trusted_admin_list"]🔗 References
- http://www.openwall.com/lists/oss-security/2023/08/31/1
- http://www.openwall.com/lists/oss-security/2023/10/27/1
- https://lists.debian.org/debian-lts-announce/2023/10/msg00000.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVKQ6Y2JFJRWPFOZUOTFO3H27BK5GGOG/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TJNJMD67QIT6LXLKWSHFM47DCLRSMT6W/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZJM6HDRQYS74JA7YNKQBFH2XSZ52HEWH/
- https://security.netapp.com/advisory/ntap-20231013-0002/
- https://www.debian.org/security/2023/dsa-5493
- https://www.vmware.com/security/advisories/VMSA-2023-0019.html
- http://www.openwall.com/lists/oss-security/2023/08/31/1
- http://www.openwall.com/lists/oss-security/2023/10/27/1
- https://lists.debian.org/debian-lts-announce/2023/10/msg00000.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVKQ6Y2JFJRWPFOZUOTFO3H27BK5GGOG/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TJNJMD67QIT6LXLKWSHFM47DCLRSMT6W/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZJM6HDRQYS74JA7YNKQBFH2XSZ52HEWH/
- https://security.netapp.com/advisory/ntap-20231013-0002/
- https://www.debian.org/security/2023/dsa-5493
- https://www.vmware.com/security/advisories/VMSA-2023-0019.html
