CriticalCVE-2024-37085

    VMware ESXi Authentication Bypass Vulnerability (CVE-2024-37085)

    Published In CISA KEV since Sources: SingCERT, pwn.watch, CVE.org

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    What is affected, what to do

    VMware ESXi contains an authentication bypass vulnerability. A malicious actor with sufficient Active Directory (AD) permissions can gain full access to an ESXi host that was previously configured to use AD for user management https://blogs.vmware.com/vsphere/2012/09/joining-vsphere-hosts-to-active-directory.html by re-creating the configured AD group ('ESXi Admins' by default) after it was deleted from AD.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update cloud_foundation to version 5.2. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • VMware ESXi gte 8.0..*
    • VMware ESXi eq 7.0..7.0
    • VMware Cloud Foundation eq 5.x..5.x
    • VMware Cloud Foundation eq 4.x..4.x

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.2

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    6.8

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: SingCERT, pwn.watch, CVE.org

    26.8 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.0

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    241.33 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: CERT.at, CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.2 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    26.8 %
    Elevated — model estimates 10-50% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    98.0
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 31 July 2024
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-305

    Response and mitigation

    Why act now?

    Prioritisation rationale

    High privileges are required, but in Active Directory rather than on the hypervisor. That makes this a classic post-compromise step: any attacker holding an account that can create groups gains full control of every domain-joined host without further exploitation. CISA flags known ransomware use, where the technique is used after AD takeover to encrypt the entire VM estate in one move, and exploitation likelihood is very high relative to other CVEs. If you run AD-joined ESXi, treat this as critical and remediate within 24 hours regardless of the moderate base severity; without AD integration the risk is low, but your inventory must prove that.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Identify every ESXi host joined to an AD domain. PowerCLI: Get-VMHost | Get-VMHostAuthentication | Select VMHost,Domain,DomainMembershipStatus. Only domain-joined hosts are exposed, including ESXi hosts inside VMware Cloud Foundation 4.0–5.2.
      • Patch where available: A patch is available from the vendor (Broadcom/VMware); look up the exact version in the vendor advisory. Some release lines, Cloud Foundation among them, may only receive a workaround rather than a fix. Verify the status per build and apply the configuration changes below immediately where no fix exists.
      • Audit the AD group: Check whether the configured admin group exists in AD and when it was created or modified. This is "ESX Admins"/"ESXi Admins" by default, or whatever value is set in Config.HostAgent.plugins.hostsvc.esxAdminsGroup. Use Get-ADGroup -Identity "ESX Admins" -Properties whenCreated,whenChanged,members. Treat a recently re-created group or unknown members as an incident.
      • Disable auto-grant: On every domain-joined host, set Config.HostAgent.plugins.hostsvc.esxAdminsGroupAutoAdd = false and adjust Config.HostAgent.plugins.vimsvc.authValidateInterval per the advisory. PowerCLI: Get-AdvancedSetting -Entity $vmhost -Name Config.HostAgent.plugins.hostsvc.esxAdminsGroupAutoAdd | Set-AdvancedSetting -Value $false.
      • Clean up host permissions: Under Host → Permissions, remove entries referencing the default group. Bind the Administrator role only to an explicitly named, protected group.
      • If compromise is suspected: Isolate affected hosts from the management network, protect snapshots and backups from encryption, and rotate root and vCenter service account credentials.

    2. Runbook step 2

      Mitigation layers

      • Configuration: Point esxAdminsGroup at a non-default group that already exists and whose creation, renaming and membership are restricted to Tier-0 admins. A group name an attacker can simply create is the attack vector.
      • IAM/AD hardening: Review delegated rights to create groups and modify membership (Create Group Objects, Write Members) across OUs and restrict them to Tier-0. Place ESXi-related AD objects in a protected OU model.
      • Reduce dependency: Where direct AD login to hosts isn't required, remove ESXi from the domain and manage exclusively through vCenter SSO. Enable Lockdown Mode (Normal or Strict).
      • Network segmentation: Restrict ESXi management interfaces (TCP 443, 902, SSH 22) to a dedicated admin VLAN or jump hosts. Drop client and server VLAN traffic to the management VLAN at the firewall.
      • Minimise services: Keep SSH and ESXi Shell disabled by default and enable them only for time-boxed windows. Enforce execInstalledOnly (esxcli system settings kernel set -s execInstalledOnly -v TRUE) to block unsigned binaries such as ransomware encryptors.

    3. Runbook step 3

      Detection rules

      • AD Security log (DCs): Event IDs 4727/4731/4754 (group created), 4728/4732/4756 (member added) and 4781/4737 (group renamed or changed) where the group is "ESX Admins"/"ESXi Admins" or the configured value. KQL: SecurityEvent | where EventID in (4727,4731,4754,4728,4732,4756,4781,4737) | where TargetUserName has_any ("ESX Admins","ESXi Admins")
      • Sigma shape: logsource: product=windows, service=security; selection: EventID|in [4727,4728,4731,4732,4781] AND TargetUserName|contains 'ESX'. Alert at high severity, since this activity is near-zero in normal operations.
      • ESXi logs (syslog forwarded to SIEM): In /var/log/hostd.log and /var/log/auth.log, look for successful logins by domain accounts (DOMAIN\user) holding the admin role that aren't in the baseline. In /var/log/shell.log, watch for esxcli vm process kill, vim-cmd vmsvc/getallvms or esxcli system settings kernel set shortly after an AD login.
      • Correlation: A group creation or membership change on a DC, followed by the same account logging into an ESXi host within roughly 60 minutes. SPL idea: index=wineventlog EventCode IN (4727,4728) Group_Name="*ESX*" | join Account_Name [search index=esxi sourcetype=hostd "logged in"]
      • Network telemetry (Zeek/Suricata): New SSH (TCP 22) or host-client HTTPS (TCP 443) sessions to ESXi management IPs from non-admin subnets. Also watch for unusually large outbound transfers from ESXi hosts, which may indicate exfiltration before encryption.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    VMware ESXi contains an authentication bypass vulnerability. A malicious actor with sufficient Active Directory (AD) permissions can gain full access to an ESXi host that was previously configured to use AD for user management https://blogs.vmware.com/vsphere/2012/09/joining-vsphere-hosts-to-active-directory.html by re-creating the configured AD group ('ESXi Admins' by default) after it was deleted from AD.

    Source: CSA/SingCERT, pwn.watch, NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    —VMware Cloud Foundation
    • 4.x
    • 5.x
    • —
    • —
    —VMware ESXi
    • 7.0
    • ≥ 8.0
    • —
    • —
    vmwarecloud_foundation
    • 4.0 – < 5.2
    • 5.2

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othervmwareesxi7.0
    Othervmwareesxi8.0

    Weakness classes (CWE)

    • CWE-305Authentication Bypass by Primary Weakness

      Base

      The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.

      Entry at MITRE CWE-305

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    CSA/SingCERTVulnerability in VMware ESXi Hypervisor (opens in a new tab)CSA/SingCERTactively exploited

    References & sources

    • support.broadcom.comVMware advisory: CVE-2024-37085Patch, Vendor advisory, pwn-watch
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2024-37085government-resource, US government resource
    • cert.atCERT.at: Kritische Sicherheitslücke in VMware ESXi - aktiv ausgenutzt - Update verfügbarcert-at
    • pwn.watchpwn.watch: VMware ESXi Authentication Bypasspwn-watch
    • microsoft.comRansomware operators exploit ESXi hypervisor vulnerability for mass encryptionpwn-watch
    • NVD (NIST)NVD: CVE-2024-37085pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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