Stop a WAF score below GREY_MIN escalating under the grey gate #3

Merged

james merged 1 commit from grey-min-floor into main

2026-10-07 18:33:17 +00:00

james commented

2026-10-07 18:30:09 +00:00

Owner

Problem

Under CENTINELA_GATE=grey, CENTINELA_GREY_MIN only ever gated out score-0 requests. The pre-filter flagged any request with a positive WAF score, and the grey gate falls through to the pre-filter, so a score of 1 or more always reached the model.

Seen on v0.1.3 with the embedded WAF at paranoia 3 and GREY_MIN=4: 25 of 26 recent decisions for one host had waf_score 3 (CRS 942420 on ordinary session cookies) and were all escalated, then failed open as "model unavailable" once the backend queued past the budget.

Change

Suspicious() looks only at the request itself (method, path, query, headers, body). It no longer treats a WAF score as a marker.
escalate() weighs the score per gate:
- grey: at or above GreyMin, or anything the pre-filter flags. A score below the floor with no marker passes without a model call.
- suspicious: unchanged, any positive score still escalates.
- always: unchanged.
README gate descriptions updated to match.

The eval harness already computed score >= grey-min || suspicious; with the pre-filter no longer counting the score, it now matches the engine for --grey-min above 1. Results at the default of 1 are unchanged.

Tests

TestGreyGateMin (GreyMin=4): score 3 with no markers is not escalated; score 3 with a marker is; scores 4 and 7 are.
TestSuspiciousGateWAFScore: the suspicious gate still escalates a positive score and passes score 0.
TestSuspicious: a WAF score alone is no longer flagged by the pre-filter.

make vet and make test pass.

Release note

Merging to main runs build-and-push, which tags and publishes the next patch version.

## Problem Under `CENTINELA_GATE=grey`, `CENTINELA_GREY_MIN` only ever gated out score-0 requests. The pre-filter flagged any request with a positive WAF score, and the grey gate falls through to the pre-filter, so a score of 1 or more always reached the model. Seen on v0.1.3 with the embedded WAF at paranoia 3 and `GREY_MIN=4`: 25 of 26 recent decisions for one host had `waf_score` 3 (CRS 942420 on ordinary session cookies) and were all escalated, then failed open as "model unavailable" once the backend queued past the budget. ## Change - `Suspicious()` looks only at the request itself (method, path, query, headers, body). It no longer treats a WAF score as a marker. - `escalate()` weighs the score per gate: - `grey`: at or above `GreyMin`, or anything the pre-filter flags. A score below the floor with no marker passes without a model call. - `suspicious`: unchanged, any positive score still escalates. - `always`: unchanged. - README gate descriptions updated to match. The eval harness already computed `score >= grey-min || suspicious`; with the pre-filter no longer counting the score, it now matches the engine for `--grey-min` above 1. Results at the default of 1 are unchanged. ## Tests - `TestGreyGateMin` (`GreyMin=4`): score 3 with no markers is not escalated; score 3 with a marker is; scores 4 and 7 are. - `TestSuspiciousGateWAFScore`: the suspicious gate still escalates a positive score and passes score 0. - `TestSuspicious`: a WAF score alone is no longer flagged by the pre-filter. `make vet` and `make test` pass. ## Release note Merging to `main` runs `build-and-push`, which tags and publishes the next patch version.

james added 1 commit

2026-10-07 18:30:10 +00:00

Stop a WAF score below GREY_MIN escalating under the grey gate

security-scan / security-scan (pull_request) Successful in 1m16s

Details

test / go (pull_request) Successful in 4m27s

Details

6465bddbcc

The pre-filter flagged any request with a positive WAF score, and the
grey gate falls through to the pre-filter, so CENTINELA_GREY_MIN only
ever gated out score-0 requests. With GREY_MIN=4 at paranoia 3, CRS
942420 firing on ordinary session cookies (score 3) sent nearly every
logged-in request to the model.

Suspicious() now looks only at the request text. The engine weighs the
score per gate: grey escalates at or above GreyMin, suspicious keeps
escalating any positive score. The pre-filter's markers still escalate
under grey, so score-0 recon is covered as before.

The eval harness already computed "score >= grey-min || suspicious"; it
now matches the engine for grey-min above 1 as well. Results at the
default grey-min of 1 are unchanged.

forgejo-actions commented

2026-10-07 18:31:21 +00:00

🔎 ojo scan results

Severity	Count
🟠 HIGH	1
🟢 LOW	1

Details (2)

Type	Severity	ID/Rule	Location	Description
vuln	🟠 HIGH	CVE-2026-41510	github.com/corazawaf/coraza/[email protected]	Coraza: Silent argument drop at ArgumentLimit allows bypass of ARGS-targeted rules via parameter flooding
misconfig	🟢 LOW	dockerfile-no-healthcheck	Dockerfile:1	image has no HEALTHCHECK

### 🔎 ojo scan results | Severity | Count | |---|---| | 🟠 HIGH | 1 | | 🟢 LOW | 1 | <details><summary>Details (2)</summary> | Type | Severity | ID/Rule | Location | Description | |---|---|---|---|---| | vuln | 🟠 HIGH | <a href="https://github.com/corazawaf/coraza/security/advisories/GHSA-6r3q-mjv7-xr8m" target="_blank" rel="noopener noreferrer">CVE-2026-41510</a> | github.com/corazawaf/coraza/[email protected] | Coraza: Silent argument drop at ArgumentLimit allows bypass of ARGS-targeted rules via parameter flooding | | misconfig | 🟢 LOW | dockerfile-no-healthcheck | <a href="https://git.colibrisec.org/ColibriSec/centinela/src/commit/6465bddbcc62a16185a673b462d4675c858745bb/Dockerfile#L1" target="_blank" rel="noopener noreferrer">Dockerfile:1</a> | image has no HEALTHCHECK | </details>

james merged commit 476456de08 into main

2026-10-07 18:33:17 +00:00

james deleted branch grey-min-floor

2026-10-07 18:33:18 +00:00

james referenced this pull request from a commit

2026-10-07 18:33:19 +00:00

Merge pull request 'Stop a WAF score below GREY_MIN escalating under the grey gate' (#3) from grey-min-floor into main

james referenced this pull request

2026-10-08 15:15:47 +00:00

Move the module path to git.colibrisec.org #4