diff --git a/README.md b/README.md index e82362c..0254bd8 100644 --- a/README.md +++ b/README.md @@ -87,10 +87,12 @@ The allowlist is the `ALLOWED_DKIM_DOMAINS` Lambda environment variable (comma-s | Pipeline | `ALLOWED_DKIM_DOMAINS` | Why | |---|---|---| -| Work orders | `seahaven.com` | APM mail reaches `apm@int.seahaven.com` via a forward off `amazon@seahavenind.com`; the allowlist trusts the domain that **re-signs** DKIM on that forward (the original `hxgnsmartcloud.com` signature does not survive it). **Must be validated against a live SES-stamped header** — a plain Gmail auto-forward re-signs under the *sending Workspace* domain (`seahavenind.com` / a `*.gappssmtp.com` key), **not** `seahaven.com`; only a Google Group (or Workspace routing) with "sign as `seahaven.com`" produces `dkim=pass header.i=@seahaven.com`. If the observed re-signing domain differs, update this value (do **not** widen it to a shared key like `*.gappssmtp.com`, which any Google customer's mail would pass). The `workorder-email-processor-sender-auth-rejected` alarm pages if this assumption is wrong instead of silently dropping every work order. | +| Work orders | `seahaven.com` | APM mail reaches `apm@int.seahaven.com` via a forward off `amazon@seahavenind.com`; the allowlist trusts the domain that **re-signs** DKIM on that forward (the original `hxgnsmartcloud.com` signature does not survive it). **Validated against live SES-stamped headers (2026-07-16)** — real APM deliveries carry `dkim=pass header.i=@seahaven.com`. Note a plain Gmail auto-forward re-signs under the *sending Workspace* domain (`seahavenind.com` / a `*.gappssmtp.com` key), **not** `seahaven.com`; only a Google Group (or Workspace routing) with "sign as `seahaven.com`" produces `dkim=pass header.i=@seahaven.com`. If the observed re-signing domain differs, update this value (do **not** widen it to a shared key like `*.gappssmtp.com`, which any Google customer's mail would pass). The `workorder-email-processor-sender-auth-rejected` alarm pages if this assumption is wrong instead of silently dropping every work order. | | Purchase orders | `amazon.coupahost.com` | Coupa signs as `amazon.coupahost.com`. `amazonses.com` also passes but is deliberately not allowlisted — every SES customer's mail passes for it | -> **Clause-injection hardening:** SES echoes attacker-controlled SMTP-session tokens (`envelope-from`, `helo`, `header.from`) into its own `Authentication-Results` value, and an RFC 5321 quoted-local-part MAIL FROM may legally contain `;` and spaces. The parser therefore tokenises comment- and quoted-string-aware (RFC 8601 / RFC 5322): CFWS comments `(...)` are stripped and clauses are split only on semicolons **outside** a quoted string, so a `;` inside a quoted `envelope-from=` value can never be torn into a forged `dkim=pass` clause. +> **Clause-injection hardening:** SES echoes attacker-controlled SMTP-session tokens (`envelope-from`, `helo`, `header.from`) into its own `Authentication-Results` value, and an RFC 5321 quoted-local-part MAIL FROM may legally contain `;` and spaces. The parser therefore tokenises comment- and quoted-string-aware (RFC 8601 / RFC 5322): CFWS comments `(...)` are stripped and clauses are split only on semicolons **outside** a quoted string, so a `;` inside a quoted `envelope-from=` value can never be torn into a forged `dkim=pass` clause. The DKIM signer domain is read from `header.d=` when present (falling back to `header.i=`, taking the domain after the AUID's last top-level `@` so a quoted local-part cannot smuggle an allowlisted domain). Two latent comment-parsing edge cases (early comment-close, no-separator-on-strip) are tracked as hardening follow-ups — see the SES-AR-01/02 issue; neither is reachable through SES's real header encoding today. + +> **Risk acceptance — forwarder-domain binding (INFRA-107, accepted 2026-07-16):** for work orders this control authenticates the domain that *re-signs* the `apm@` forward (`seahaven.com`), not the Hexagon originator (`hxgnsmartcloud.com`, whose signature does not survive the forward). Its strength therefore rests on the `apm@` Google Group's posting policy being restricted to trusted internal senders — that restriction is the **load-bearing control** and is accepted as documented risk. **If the `apm@` group is ever opened to external posting, this finding escalates to HIGH** (anyone able to post to the group could inject a forged work order) and the correct fix is to bind acceptance to the originator via DMARC alignment rather than the forwarder's re-signature. The PO pipeline is unaffected — `amazon.coupahost.com` is an external domain an attacker cannot get SES to sign. On any failure (env var unset, header missing/unparseable, verdict fail, unaligned domain) the processor logs a structured `sender_auth_rejected` warning with the reason and S3 key, skips the email, and returns normally — rejected mail never triggers Lambda retries or DLQ messages, but the `-sender-auth-rejected` CloudWatch alarm (see [CloudWatch alarms](#cloudwatch-alarms)) pages on a rejection spike so a drift-induced outage is not silent. Unit tests live in `tests/test_ses_auth.py`. @@ -107,9 +109,9 @@ Every alarm is **ALARM-only** (no OK action), sends to the shared `site-alerts` | `-errors` | `po-email-processor`, `po-ingest-site-extractor`, `workorder-email-processor` | `Errors` Sum, 5 min, `> 0`, eval 1 | | `-throttles` | `po-email-processor`, `po-ingest-site-extractor`, `po-web-ui`, `workorder-email-processor` | `Throttles` Sum, 5 min, `> 0`, eval 1 | | `-duration` | `po-email-processor`, `po-ingest-site-extractor`, `po-web-ui` (p99); `workorder-email-processor` (p95) | `Duration` percentile, 5 min, `>= 45000` ms (75% of the 60s timeout), eval 3 / datapoints 2 | -| `-sender-auth-rejected` | `po-email-processor`, `workorder-email-processor` | Log-metric-filter count (namespace `Seahaven/ProcurementIngest`, `default_value=0`) on `sender_auth_rejected` warnings, `Sum` 15 min, `>= 3`, eval 1 | +| `-sender-auth-rejected` | `po-email-processor`, `workorder-email-processor` | Log-metric-filter count (namespace `Seahaven/ProcurementIngest`, `default_value=0`) on `sender_auth_rejected` warnings, `Sum` 5 min, `>= 1`, eval 3 / datapoints 2 | -The `-sender-auth-rejected` alarm closes the silent-drop gap in INFRA-107: a rejected email returns normally (no error, no retry, no DLQ message), so without a log-metric filter a signing-domain drift or a wrong allowlist would discard 100% of legitimate mail while every other alarm stayed green. `>= 3` rejections in 15 minutes tolerates the occasional spoofed probe to the internal ingest address but pages quickly on a genuine false-reject storm; the threshold is easy to tune in the CDK helper. +The `-sender-auth-rejected` alarm closes the silent-drop gap in INFRA-107: a rejected email returns normally (no error, no retry, no DLQ message), so without a log-metric filter a signing-domain drift or a wrong allowlist would discard 100% of legitimate mail while every other alarm stayed green. It counts `sender_auth_rejected` warnings per 5-minute period (`default_value=0` keeps the series continuous) and pages when 2 of the last 3 periods each see at least one rejection — a lone stray spoof probe to the internal ingest address self-clears, but a sustained false-reject storm pages within ~10–15 minutes even at low mail volume; the config is easy to tune in the CDK helper. (A residual gap remains for a *very* sparse total-reject outage — see the SES-AR-01/02 hardening issue.) The `-duration` and `-throttles` alarms for `po-email-processor` and `workorder-email-processor` supersede the orphaned, CLI-created `Lambda-Duration-*` / `Lambda-Throttles-*` alarms (deleted post-deploy).