VNX-SEC-065: HTTP basic authentication header

Detects literal HTTP Basic credentials: a "Basic <base64>" header value that decodes to a real user:password pair.

Field	Value
Rule ID	`VNX-SEC-065`
Severity	High
SARIF level	`error`
Kind	`secrets`
Languages	Any file
CWE	CWE-798
CAPEC	CAPEC-191
ATT&CK	T1552.001
CWSS vector	`CWSS:1.0/TI:H/AP:A/AL:A/IC:N/FC:LT/RP:N/RL:A/AV:I/AS:N/IN:A/SC:A/BI:H/DI:H/EX:H/EC:N/P:H`
Tags	`secrets` `http` `basic-auth` `credentials`
Source	`internal/sast/rules/vnx-sec-065.rego`

Overview

This rule reports the string Basic <base64> (an Authorization header in a .http file, a curl -H argument, a headers dict or object, a Header.Set call, a constant, or the two-argument .NET new AuthenticationHeaderValue("Basic", "...")) when the base64 decodes to a printable user:password pair with a non-empty password. The decoded password is never printed.

It does not report headers built from variables ("Basic " + token, f-strings, ${VAR}, $(...)), text that does not decode to a credential (Basic authentication, Basic realm), default or placeholder pairs (admin:password, user:pass, a password equal to the user), comment lines, Markdown/reStructuredText/AsciiDoc, and test, fixture, vendored and generated files.

What Gets Flagged

HEADERS = {"Authorization": "Basic c3ZjLWRlcGxveTpUcTh2TDJtWnA5V3g="}   # svc-deploy:Tq8vL2mZp9Wx

req.Header.Set("Authorization", "Basic c3ZjLWRlcGxveTpUcTh2TDJtWnA5V3g=")

Not flagged:

headers = {"Authorization": "Basic " + token}
DEFAULT = {"Authorization": "Basic YWRtaW46cGFzc3dvcmQ="}   # admin:password

Why This Matters

Hardcoded http basic authentication header 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-065
// nosec vnx-sec-065

Or record an ignore rule: vulnetix ignore add --rule vnx-sec-065 --reason "...". See Suppressing findings.