VMware Harden

vmware-harden

For a read-only check of this skill with your model and agent host, use the shared model-fit self-test in the marketplace root.

Disclaimer: Community-maintained open-source project. Not affiliated with, endorsed by, or sponsored by VMware, Inc. or Broadcom Inc. "VMware", "vSphere", "ESXi", and "NSX" are trademarks of Broadcom. Source code is publicly auditable at github.com/vmware-skills/VMware-Harden under the MIT license.

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AI-native VMware compliance and baseline enforcement. Sibling to the vmware-* skill family.

• Read-only against vSphere: all 8 MCP tools carry the [READ] marker and none mutate managed VMware infrastructure; scan_target writes only to the local twin DB (a cache of its own observations). See Read-only by design.

GA family member (since v1.5.18)

Production-ready compliance platform with 9 built-in baselines (CIS ESXi 8.0 + 9.0, vSphere SCG v8 + v9, vSphere 9 STIG-aligned, 等保 2.0 三级, PCI-DSS 4.0, EU NIS2, BSI IT-Grundschutz) carrying 99 rules, a VMSA known-vulnerability check for ESXi and vCenter builds, multi-vCenter Twin, drift detection, LLM Remediation Advisor, MCP server with 8 audited tools, web dashboard, and vmware-harden doctor environment diagnostics.

Quickstart

# The collectors extra is what makes `scan` work: harden reads inventory# through vmware-aiops / vmware-storage / vmware-nsx-security, and `uv tool# install` gives each tool its own environment — installing them separately# puts them where harden cannot import them from.uv tool install "vmware-harden[collectors]"
# Reporting on an existing twin DB needs no collectors:#   uv tool install vmware-harden
# List built-in baselinesvmware-harden baseline list
# Run a scanvmware-harden scan --target <vcenter-name> --baseline cis-vmware-esxi-8.0-subset
# Or use 等保 2.0 三级 (国内合规独家)vmware-harden scan --target <vc> --baseline dengbao-2.0-level3-vmware
# View resultsvmware-harden reportvmware-harden drift
# Generate remediation suggestionsexport ANTHROPIC_API_KEY=...  # optional; falls back to mock withoutvmware-harden advise --all-critical
# Web dashboardvmware-harden web --port 8080  # → http://127.0.0.1:8080

Reading a result: violations alone are not a verdict

A rule can only judge configuration that was actually gathered, and that fails in two independent ways. A rule whose attribute no collector produces is not executed at all. A rule that does run can still learn nothing about one particular host, because there the value came back absent or as the N/A sentinel — an unreachable host, an account without the privilege, a setting the ESXi build does not have. Neither is reported as passing:

$ vmware-harden reportNo violations among the checks that could be made.
16 of 20 rules could not be evaluated — no collector provides the data theycheck, so their result is unknown, not compliant. 6 of 8 per-node checks couldnot be made across 2 node(s): the rules ran, but the values they read weremissing on those nodes, so those nodes are unknown rather than compliant.Not evaluated:  cis-esxi-2.1.1   no collector writes host.ntp_enabled  ...Not judged on these nodes (data missing):  cis-esxi-2.2.1   esx-02    esxi_build  ...

--format json returns {"violations": [...], "coverage": {...}}, and the MCP tools return the same coverage block, so an agent reading violations: 0 cannot conclude "compliant" on its own. Before v1.9.0 the uncollected-attribute rules matched zero rows and were silently counted as passes; before v1.10.0 the per-node case was, too. See RELEASE_NOTES.md.

The two lists call for different work: the first is waiting on a collector, the second on that node's reachability and the scanning account's privileges.

Offline / Air-Gapped Install (from source)

This project uses the modern PEP 517 build system (hatchling), so there is no setup.py by design — that is expected, not a missing file. If you cloned the source and hit ERROR: File "setup.py" or "setup.cfg" not found ... editable mode currently requires a setuptools-based build, your pip is older than 21.3 and cannot do an editable (-e) install with a non-setuptools backend. Editable mode is a developer convenience, not needed to run the tool — do one of:

# From the source tree — a normal (non-editable) install builds a wheel:pip install .              # NOT  pip install -e .
# ...or upgrade pip first, and editable works too:pip install --upgrade pip && pip install -e .

For a truly air-gapped host, build the wheels on a connected machine and copy them over — the target then needs no network:

# On a connected machine, collect this package + its dependencies as wheels:pip wheel . -w dist        # → dist/*.whl   (or: uv build, for just this package)
# Copy dist/ to the air-gapped host, then install offline:pip install --no-index --find-links dist vmware-harden

Read-Only by Design

vmware-harden is read-only against vSphere and NSX — all 8 MCP tools carry the [READ] marker, and none mutate managed VMware infrastructure. scan_target writes only to the local twin DB (~/.vmware-harden/twin.duckdb), a cache of its own observations rather than managed infrastructure. Remediation is never applied by this skill; it is deferred to vmware-pilot, which provides approval gating and audit trails for write operations.

Built-in baselines

baseline list returns 10 IDs: the 7 rule-bearing YAML baselines above (99 rules total), the two v9 aliases, which carry no rules of their own and resolve to their v8 parent's, and vmsa-advisories, which is generated from the advisory catalog rather than read from a file.

Known vulnerabilities (VMSA)

vmsa-advisories judges each ESXi host's and the vCenter's own version and build against an offline catalog of VMware security advisories shipped in the package (vmware_harden/advisories/catalog.yaml, checked against its sources on the catalog date). One rule per advisory; each rule's text quotes the 等保 2.0 三级 control it evidences (安全计算环境·入侵防范: find known vulnerabilities and patch them after testing).

vmware-harden scan --target prod-vc --baseline vmsa-advisoriesvmware-harden report                    # each affected component: its fix, and whether the CVE is in CISA KEVvmware-harden report --format csv > vmsa.csv

A clean result means no open advisory known as of the catalog date, not "not vulnerable": advisories published later are not in the catalog. Builds are compared only within one major.minor line (a 7.0 U3 build can be numerically larger than an 8.0 GA build).

How the catalog is built. Broadcom's advisory pages are behind a bot challenge and cannot be read by a script, and Broadcom publishes no CSAF feed. Each entry is assembled from the NVD CVE API (CVEs, CVSS, vulnerable versions), the CISA KEV feed (exploited in the wild), and Broadcom's build-number KB articles (fixed builds), with each fixed release confirmed against an independent source quoting the advisory. Every fix is checked mechanically against a snapshot of the build KB in builds.yaml. The first catalog (2026-10-19) carries three KEV-listed advisories: VMSA-2025-0004 (ESXi), VMSA-2024-0019 and VMSA-2026-0006 (vCenter; its ESX half is not catalogued yet and reports unknown).

Optional refresh. vmware-harden advisories update downloads the CISA KEV feed (and, with --nvd, NVD scores) into ~/.vmware-harden/advisories-cache.json, which the catalog loader overlays: KEV flags are only ever added, CVSS only filled where missing, and fixed builds are never taken from it. It also lists ESXi/vCenter CVEs in KEV that no catalogued advisory covers. A failed KEV fetch exits 1 and leaves the previous cache unchanged; an NVD record that cannot be read is reported and does not block the KEV refresh. A running MCP server picks up a new cache on its next call. Reports show when KEV was last checked. vmware-harden advisories show prints the catalog date and the last refresh.

VCF 9.0 / 9.1 Compatibility

The existing baselines (cis-vmware-esxi-8.0-subset, vsphere-scg-v8, dengbao-2.0-level3-vmware, pci-dss-4.0-vmware) scan VCF 9.0 / 9.1 clusters successfully — most rules target host advanced settings stable across 8.x → 9.x. cis-vmware-esxi-9.0-subset and vsphere-scg-v9-subset ship today as extends: aliases of their v8 parents — same rules, a v9-named ID to scan and report under. Rules specific to 9.x will be added to them as Broadcom publishes the v9 guides.

vsphere-stig-v9-subset is a rule-bearing STIG-aligned baseline: 12 host advanced-setting controls (account lockout, password policy, DCUI access, shell/DCUI timeouts, MOB, guest BPDU, remote syslog) mapped to the official open-source vSphere STIG content (MITRE InSpec / Cinc Auditor). Status: experimental. Its checks read ESXi host advanced settings the host collector fetches via a config.option PropertyCollector pass. That pass was verified end-to-end on 2026-08-13 against a live standalone ESXi 8.0.3 (build 24280767): all 12 attributes came back populated, with values in the shapes the rules expect (account_lock_failures=5, dcui_access='root', password_quality_control='retry=3 min=disabled,disabled,disabled,7,7', mob_enabled=False, syslog_remote_host=''), and the scan raised 3 genuine violations. Still unverified, and why the status stays experimental: ESXi 9.x, which is what this baseline actually targets, and any vCenter-managed multi-host inventory. Treat results on 9.x as non-authoritative. The v1.9.0 undetermined mechanism does not cover a failed fetch on its own: it refuses a rule when no collector declares the attribute, a static check against the vocabulary, and these STIG attributes are declared, so their rules do run. If the real PropertyCollector pass comes back empty on live hardware, the attribute is simply absent and the rule again matches zero rows. v1.10.0 catches that case — such a host is recorded as a per-node gap (coverage.undetermined_node_checks) rather than a pass, so an unverified collector shows up as unjudged hosts instead of a clean report. What remains unverified is whether the pass returns the right values, which no coverage mechanism can tell you. The baseline's status field is surfaced by list_baselines and describe_stig_content_sync so a scan self-declares this caveat. It is a content sync, not an API wrapper — VCF Operations 9.1 Automated Configuration Compliance (ACC) / Security Posture Management (SPM) is UI- and schedule-driven and exposes no public compliance REST API. For continuous, fleet-wide enforcement and automated remediation, use VCF Operations SPM/ACC (UI); vmware-harden is the API-scriptable, DuckDB-persisted, cross-target point-in-time scanner. See references/stig-content-sync.md and inspect the catalog with vmware-harden stig controls.

Official Broadcom References

• Security Configuration Guides: https://core.vmware.com/security/ — vSphere SCG v8 / future v9
• SDKs: https://developer.broadcom.com/sdks — VCF Python SDK (for fetching host config via REST)
• CIS Benchmarks: https://www.cisecurity.org/cis-benchmarks/ — CIS VMware ESXi Benchmark v1.0 (8.0 / future 9.0)

Custom baselines

vmware-harden baseline validate ./my-strict.yamlvmware-harden baseline import ./my-strict.yaml --name my-strict-cisvmware-harden scan --target <vc> --baseline my-strict-cis

YAML supports extends: for inheriting from a built-in baseline. See skills/vmware-harden/references/cli-reference.md.

MCP server

vmware-harden mcp  # stdio MCP server (legacy alias: vmware-harden-mcp)

Configure your MCP client with one of examples/mcp-configs/*.json. 8 read-only tools: list_baselines, get_baseline_rules, list_stig_controls, describe_stig_content_sync, list_violations, get_remediation, list_drift_events, scan_target.

Architecture

• Estate Digital Twin — DuckDB single file at ~/.vmware-harden/twin.duckdb. Multi-target safe via target prefix on all node IDs.
• Collectors — lazy-import sibling vmware-* skills (no spawn overhead). All scans are READ; writes deferred to vmware-pilot.
• Baseline schema — Pydantic v2, strict (extra="forbid"), extends: inheritance, user-dir override.
• Drift — pure diff function with optional persistence; auto-runs after every scan.
• Advisor — LLM-driven Suggestion generation; Anthropic provider with prompt caching; mock fallback for tests / no-API-key environments.
• Audit — every MCP tool wrapped with @vmware_tool from family vmware-policy.
• Web — FastAPI + Jinja2 + Tailwind/HTMX/ECharts CDN.

Lab regression

export VMWARE_HARDEN_LAB_TARGET=<your-vc>pytest tests/eval/regression -v -m lab

Family

• vmware-aiops — host inventory + ops (used by harden's HostCollector)
• vmware-monitor — read-only counterpart
• vmware-storage — datastore inventory
• vmware-nsx-security — DFW inventory
• vmware-pilot — execute remediations (writes; out of scope for harden)
• vmware-policy — @vmware_tool audit decorator

Acceptance criteria (v1.5.18 GA)

• 221 tests passing
• Bandit: 0 issues at any severity
• All 8 MCP tools audited
• SKILL.md ≤ 3000 words, family-convention compliant
• SECURITY.md with 6 elements + Broadcom disclaimer
• 9 built-in baselines (99 rules across 7 rule-bearing sets + 2 v9 aliases)
• vmware-harden doctor for environment diagnostics
• GA member of vmware-* family (version-aligned at 1.5.28)

References

• Family CLAUDE.md: CLAUDE.md at the monorepo root

Remote access (HTTPS) and limiting tools

By default vmware-harden mcp speaks stdio to one local client and offers every tool. Two options change that (vmware-policy ≥ 1.21.0).

Serve over HTTPS so clients on other machines can connect. Every caller needs a bearer token:

vmware-audit token create alice          # prints the token once; give it to alicevmware-audit token list                  # names onlyvmware-audit token revoke alice          # refused from its next request, no restartvmware-harden mcp --transport https --host 0.0.0.0 --port 8443 \    --cert /etc/vmware-mcp/server.pem --key /etc/vmware-mcp/server-key.pem \    --public-name mcp.example.com

Connect a client (Claude Code shown; any MCP client that supports streamable HTTP and custom headers works):

claude mcp add --transport http vmware-harden https://mcp.example.com:8443/mcp \    --header "Authorization: Bearer $VMWARE_MCP_TOKEN"

{  "mcpServers": {    "vmware-harden": {      "type": "http",      "url": "https://mcp.example.com:8443/mcp",      "headers": { "Authorization": "Bearer ${VMWARE_MCP_TOKEN}" }    }  }}

• The server will not start without a token, refuses Host/Origin values outside --public-name, and checks before it binds that unauthenticated requests get 401. Use a certificate your clients trust for those names.
• Behind a TLS-terminating reverse proxy on the same machine use --transport http --host 127.0.0.1 --public-name mcp.example.com and pass the Authorization header through.
• Behind a load balancer or gateway on another machine, keep --transport https (a self-signed certificate is fine), list in --public-name the host name the balancer sends as Host, and have it forward Authorization. Its health probe can use GET /healthz, which needs no token and returns only {"status": "ok"} (vmware-policy ≥ 1.23.0).
• Send traceparent or X-Request-ID with each request to have it stored on the audit row; vmware-audit log --correlation-id ID then finds the calls behind one platform request.
• The audit log records each caller as token:<name>. Calls naming different targets run in parallel; calls that name no target run one at a time, so name the target when several people share a server.
• Everyone who can reach the endpoint acts with this server's account. Tokens identify callers; they grant nothing on the platform. Run one endpoint per privilege level.
• Several people or roles on one endpoint: run vmware-audit roles enable once, then give each token a role (vmware-audit token create NAME --role reader, or a role in roles.yaml naming tools and targets; vmware-policy ≥ 1.24.0). A role limits what the token may call on this endpoint; it cannot grant more than the account has. For a target-limited role, scan_target's target is checked against vmware-aiops' config; the datastore and DFW collectors look the same name up in vmware-storage's and vmware-nsx-security's configs, so a name must mean the same system in all three. See vmware-policy's README, "Roles for network callers".

Limiting tools: every tool of this server is read-only, so --expose read changes nothing here; it exists for the write-capable skills. Least privilege comes from the account the server uses.

Details: skills/vmware-harden/references/setup-guide.md ("Serving MCP over HTTPS", "Limiting which tools are offered").

License

MIT