VNX-SEC-071: GitLab session cookie

Detects captured GitLab session cookie values (_gitlab_session with a 32-hex session id) in any file.

Field	Value
Rule ID	`VNX-SEC-071`
Severity	Critical
SARIF level	`error`
Kind	`secrets`
Languages	Any file
CWE	CWE-798
CAPEC	CAPEC-191
ATT&CK	T1552.001
CWSS vector	`CWSS:1.0/TI:C/AP:A/AL:A/IC:N/FC:LT/RP:N/RL:A/AV:I/AS:N/IN:A/SC:A/BI:C/DI:H/EX:H/EC:N/P:W`
Tags	`secrets` `gitlab` `session` `credentials`
Source	`internal/sast/rules/vnx-sec-071.rego`

Overview

This rule reports _gitlab_session followed by = (a Cookie header, document.cookie, a curl argument) by a quoted or symbol key and :/=/=> (a cookies dict, hash or object), by a call argument pair (cookies.set("_gitlab_session", "...")) or by a tab (Netscape cookies.txt); or a cookie object whose "name" is _gitlab_session with its "value" on the same line or up to 12 lines below, as browser cookie exports write it; and then a 32-character lowercase hexadecimal session id. The value is masked in the snippet.

It does not report the cookie name on its own (Rails session_store key: "_gitlab_session"), a value read from a variable or the environment, placeholder values (all zeros, xxxx...), and generated, vendored and test-suffixed files.

What Gets Flagged

curl -s -H "Cookie: _gitlab_session=<32 hex>" https://gitlab.acme-corp.io/api/v4/projects

cookies = {"_gitlab_session": "<32 hex>"}

Not flagged:

cookies = {"_gitlab_session": os.environ["GITLAB_SESSION"]}

Why This Matters

Hardcoded gitlab session cookie values are routinely scraped by automated bots within minutes of a public push, and then used to access the account, exfiltrate data, or pivot into downstream services. Once the credential is in git history it is permanently in third-party hands.

Remediation

Revoke the leaked credential in the provider’s console immediately.
Replace with a short-lived alternative, OAuth 2.0 access tokens, IAM role assumption, OIDC federation, wherever the platform supports it.
Store the new credential in a secrets manager (AWS Secrets Manager, HashiCorp Vault, GitHub Actions secrets, Doppler).
Audit the provider’s access logs for activity you did not initiate between the leak and the revocation.
Purge from git history with git filter-repo or BFG, then re-scan with gitleaks/truffleHog to confirm no other secrets remain.
Enable push protection so future commits are blocked at the developer machine.

References

Suppressing this rule

Put a nosec comment on the line, or on line 1 to cover the whole file. Use the comment marker of the file’s language (#, //, -- or ;):

# nosec vnx-sec-071
// nosec vnx-sec-071

Or record an ignore rule: vulnetix ignore add --rule vnx-sec-071 --reason "...". See Suppressing findings.