environment attestor

Captures the host OS, hostname, username, and the full process environment (with sensitive variables obfuscated by default) at attestation time.

What it captures

Four json-tagged fields on the Attestor struct:

• os — runtime.GOOS (e.g. linux, darwin, windows). No kernel version, no architecture.
• hostname — os.Hostname().
• username — user.Current().Username.
• variables — map of every KEY=VAL entry returned by os.Environ(), after the sensitive-variable filter has been applied. Keys are always preserved; only values are touched.

Sensitive-variable filter behavior (plugins/attestors/environment/filter.go, obfuscate.go):

• The blocklist is split into two sets at runtime. Entries containing * are compiled as gobwas/glob patterns; entries without * become case-insensitive exact-match keys.
• Both the env-var key and the blocklist entry are upper-cased before comparison, so aws_secret_key matches AWS_SECRET_ACCESS_KEY and *token* matches MyToken.
• Default mode is obfuscate: matched values are replaced with the literal string ******. The key still appears in variables.
• With --env-filter-sensitive-vars, matched entries are dropped entirely — neither key nor value appears in variables.
• --env-allow-sensitive-key excludes specific keys from the filter (exact-match only, no globs).
• Credentials inside URL-shaped values are redacted whatever the key (url_credentials.go, releases after 4.4.0). The userinfo of a URL in any value becomes ****** and the scheme, host, port and path stay, so HTTP_PROXY=http://user:pass@proxy:3128 is recorded as http://******@proxy:3128. The username goes too, because a token can sit in either slot. A scheme-less user:pass@proxy:3128, which curl and Go read as http://, is redacted the same way. So is a scheme-relative //user:pass@proxy:3128, which Python's urllib reads as a proxy URL, to //******@proxy:3128. A colon-separated path list such as PATH or PKG_CONFIG_PATH is not a URL and is left alone, even when an entry holds an @ (/opt/homebrew/opt/[email protected]/bin). This runs in both modes and neither --env-disable-default-sensitive-vars nor --env-allow-sensitive-key turns it off.

The default blocklist (attestation/sensitive_env_vars.go::DefaultSensitiveEnvList) ships these glob patterns: *TOKEN*, *SECRET*, *API_KEY*, *PASSWORD*, *JWT*, *sshKey*, *passphrase*. It also carries ~70 explicit keys including AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AZURE_CLIENT_SECRET, GH_TOKEN, GOOGLE_APPLICATION_CREDENTIALS, CI_JOB_JWT, CI_JOB_JWT_V2, CI_JOB_TOKEN, VAULT_TOKEN, ACTIONS_RUNTIME_TOKEN, ACTIONS_ID_TOKEN_REQUEST_TOKEN, DOCKER_PASSWORD, NPM_AUTH_TOKEN, SLACK_TOKEN, SNYK_TOKEN, STRIPE_API_KEY, cloud-provider keys for Heroku/DigitalOcean/Vultr/Sauce/Sentry/Percy/Twilio, and the bare key TOKEN.

When to use

Always. It is one of two default-on attestors (with git) and provides the baseline host/identity context every downstream collection links back to. Disable it only if you are intentionally producing an environment-free predicate.

Flags

These four flags live on the cilock run command (in cilock/internal/options/run.go), not as --attestor-environment-* flags. The environment attestor registers no per-attestor flags of its own.

Output shape

{
  "os": "linux",
  "hostname": "runner-abc123",
  "username": "runner",
  "variables": {
    "PATH": "/usr/local/bin:/usr/bin:/bin",
    "HOME": "/home/runner",
    "GH_TOKEN": "******",
    "AWS_ACCESS_KEY_ID": "******",
    "CI_JOB_JWT": "******"
  }
}

Gotchas

• The key still leaks. In the default obfuscate mode only the value becomes ****** — GH_TOKEN, AWS_ACCESS_KEY_ID, CI_JOB_JWT_V2 etc. remain visible in the predicate. If even the presence of a key is sensitive, use --env-filter-sensitive-vars.
• cilock 4.4.0 and earlier sign URL credentials verbatim. A proxy password in HTTP_PROXY, ALL_PROXY and their siblings lands in the predicate, because those keys match nothing on the blocklist. On those versions pass --env-add-sensitive-key '*PROXY*', plus the name of any other variable that holds a credential URL.
• URL redaction never names a host the value does not dial, and errs toward naming none. The marker keeps @host only when Go, Python, WHATWG and curl read one userinfo and the same host after it. Where they do not, the URL keeps only its scheme and ******@, in which none of them finds a host: two @ in the authority (https://[email protected]@github.com/x), a password holding /, ?, # or \ (https://alice:sec/[email protected]/acme), or an @ after the authority. An @ after a ? or # with no / before it counts too: Python's proxy parser ends the authority only at a / after the userinfo's @, so http://u:pass@proxy-a?tail@proxy-b:3128 sends pass@proxy-a?tail to proxy-b and becomes http://******@. An empty userinfo does not end that search: http://@proxy-a?u:pass@proxy-b:3128 is an empty user at proxy-a to Go, curl and WHATWG, sends pass to proxy-b from Python, and becomes http://******@. A / first ends the authority for every parser, so git+https://u:pass@host/o/r.git@v1 keeps its host and path. https://evil.example/[email protected] dials evil.example in Go, WHATWG and curl, while Python's proxy parser sends evil.example/x as a userinfo to proxy.golang.org, so it becomes https://******@, and so does https://registry.npmjs.org/@scope/pkg. A scheme-less value is held to the same rule: evil.example:8080/[email protected] and DOMAIN\user:pass@proxy:8080 (which a WHATWG parser dials at domain) become ******@, and so does a compound scheme that carries a credential (jdbc:postgresql://u:pass@db/app). One pair of matching quotes around a value ("u:pass@proxy:3128", as docker --env-file keeps them) is looked through, with or without a scheme, so a space in a quoted URL's password does not end it. A value that holds a credential only once tabs and newlines are removed, as WHATWG removes them (http:/<TAB>/u:pass@h), becomes ******@. A path list is told from a scheme-less credential by a / in its first entry, or a / or \ that starts its second, so one without (.:[email protected]) is read as user:pass@host and redacted. A \ in the user does not count, because Python's urllib sends DOMAIN\user:pass@proxy:8080 as a credential. A domain holding ; (dom;ain\u:\pass@proxy:8080) is read as a Windows path list and kept; NetBIOS names cannot hold ;. A value that opens with // is held to the rules of a URL with a scheme whatever its first entry looks like, so a path list that starts with a network path (//server/share/bin:/opt/x@1/bin) becomes //******@. A package URL (pkg:npm/[email protected]), a scoped npm alias (npm:@scope/[email protected]), a mailto: address and a full-length image digest (docker://ghcr.io/o/img@sha256:<64 hex>) are references, not userinfo, and are kept. Each shape is held tight: add a port, a list entry or a second @ and the value is redacted. What shape leaves open is a proxy user literally named mailto, or pkg or npm with a password shaped like the rest of a reference, on a proxy with no port. A token in a query string (?token=, a presigned X-Amz-Signature) is not userinfo and is not redacted; name its variable with --env-add-sensitive-key.
• Glob vs exact is decided by *. A blocklist entry like MY_SECRET is exact-match (case-insensitive); MY_SECRET* is a glob. Half-baked patterns like MY_SECRET_ will only match that literal key. There is no regex support.
• Glob patterns are normalised to uppercase. Mixed-case patterns like *sshKey* and *passphrase* in the default list are upper-cased at compile time, then matched against upper-cased keys — so they catch any casing.
• Panic-safe matching. safeGlobMatch recovers from gobwas/glob panics on adversarial patterns and treats them as non-matches; an unmatched-due-to-panic value is not filtered. Audit custom patterns before trusting them.
• No kernel, no arch. Despite what older witness docs imply, this attestor records only runtime.GOOS — not kernel version, not runtime.GOARCH. Hardware/kernel context must come from a separate attestor.
• Shared capturer. Attest writes the capturer into AttestationContext.SetEnvironmentCapturer so other attestors (e.g. command-run) apply the same filter to any environment they record.

CLI example

Default. Captures the process's ENV vars; sensitive keys (TOKEN, KEY, SECRET, PASSWORD) are redacted to ****.

cilock run --step my-step \
  --signer-file-key-path key.pem --outfile attestation.json \
  --attestations environment \
  -- echo hi 

Validated. Default attestor. See the full real-data example at https://github.com/aflock-ai/attestor-compliance-examples/tree/main/04-environment.

See also

• Catalog row
• Upstream: witness/environment.md