---
title: "NET-TLS-004 Weak TLS 1.2 Cipher Suites Accepted"
canonical: https://openvapt.com/checks/NET-TLS-004.html
html: https://openvapt.com/checks/NET-TLS-004.html
site: OpenVAPT, https://openvapt.com/
license: OpenVAPT Source-Available Licence 1.3, https://openvapt.com/legal/licence-text.html
modified: 2026-10-14
version: 0.1.0-alpha.6
---

# NET-TLS-004 Weak TLS 1.2 Cipher Suites Accepted

A local TLS service accepts an RC4, 3DES, or CBC with SHA-1 cipher suite under TLS 1.2.

- Domain: Network
- Severity: Medium
- Control category: Cryptography and TLS
- Fix effort: low
- CVSS v3.1 vector: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N`
- CIS Controls v8: 3.10
- NIST CSF 2.0: PR.DS-02
- CWE: CWE-326, CWE-327
- OWASP Top 10 2021: A02:2021
- OWASP ASVS 4.0.3: 9.1.3
- OWASP WSTG v4.2: WSTG-CRYP-01
- NIST SP 800-53 Rev. 5: SC-8, SC-13

## Why It Matters

Obsolete cipher constructions lack modern authenticated encryption and are prohibited by current TLS hardening guidance.

## How It Detects

Offers restricted TLS 1.2 cipher lists to loopback services. A successful handshake proves the weak suite is accepted. Go does not implement NULL, EXPORT, or anonymous suites, so those cannot be actively offered and remain a documented limitation.

## How to Fix

Allow only modern AEAD suites for TLS 1.2 and prefer TLS 1.3. Remove RC4, 3DES, NULL, EXPORT, anonymous, and CBC with SHA-1 suites. Caution: very old clients and devices that support only those suites stop connecting; check the access logs for them first.

## How to Verify

```
Use an approved local TLS scanner and confirm each prohibited TLS 1.2 suite is rejected. Implicit TLS mail ports 465, 993, and 995 are included; STARTTLS is out of scope.
```

## Learn the Theory

- [P4 TLS, Certificates and HTTPS](https://openvapt.com/academy/p4.md)

## References

- [RFC 8996, Deprecating TLS 1.0 and TLS 1.1](https://www.rfc-editor.org/rfc/rfc8996.html)
- [NIST SP 800-52 Rev. 2, Guidelines for TLS Implementations](https://csrc.nist.gov/pubs/sp/800/52/r2/final)
- [Mozilla Server Side TLS guidelines](https://wiki.mozilla.org/Security/Server_Side_TLS)

## Source Code

https://github.com/OpenVAPT/openvapt/blob/574f7f3333c44b75a3c649e2d93a76d507f75adf/internal/checks/network/tls_depth.go

Run it: `openvapt scan --only NET-TLS-004`. Read it offline: `openvapt explain NET-TLS-004`.

---

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