# Cis Bind9 V301 3 1

> Cis Bind9 V301 3 1 is an Agent Skill for devops & security published in the CyberStrikeus/CyberStrike repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Ignore Erroneous or Unwanted Queries (Automated)

- Skill name: `cis-bind9-v301-3-1`
- Category: [DevOps & Security](https://www.openparable.com/skill/devops-security/1)
- Source: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Server_Software/Bind/CIS_ISC_BIND_DNS_Server_9.9_Benchmark_v3.0.1/cis-bind9-v301-3-1/SKILL.md
- Repository: CyberStrikeus/CyberStrike (1,211 GitHub stars when collected)

## SKILL.md

# CIS 3.1 — Ignore Erroneous or Unwanted Queries

## Profile Applicability

- Level 1 - Authoritative Name Server
- Level 1 - Caching Only Name Server

## Description

BIND can be configured to ignore requests originating from specified network segments. This is accomplished by implementing the `blackhole` option in `named.conf`. It is recommended that this feature be implemented to ignore requests that originate outside of expected network segments.

## Rationale

By ignoring traffic that originates from unexpected networks, the server's exposure to malicious entities is reduced.

## Impact

Not Applicable

## Audit Procedure

Attempt to query the server from an address that has been placed in the `blackhole` list. If properly configured, the query will fail.

```bash
nslookup www.google.com ns1.example.com
```

## Remediation

Add a `blackhole` option for multicast and link local addresses, and all private RFC 1918 addresses that are not being used.

```
blackhole {
    // Private RFC 1918 addresses
    10/8; 192.168/16; 172.16/12;
    // Multicast
    224/8;
    // Link Local
    169.254/16;
};
```

## Default Value

No networks are blackhole'd by default.

## References

Not Applicable

## CIS Controls

| Controls Version | Control                                                              | IG 1 | IG 2 | IG 3 |
| ---------------- | -------------------------------------------------------------------- | ---- | ---- | ---- |
| v6               | 9 - Limitation and Control of Network Ports, Protocols, and Services | N    | Y    | Y    |

## MITRE ATT&CK Mappings

| Tactic         | Technique                                 |
| -------------- | ----------------------------------------- |
| Reconnaissance | T1590 - Gather Victim Network Information |
| Initial Access | T1190 - Exploit Public-Facing Application |

## Profile

- Level 1 - Authoritative Name Server
- Level 1 - Caching Only Name Server

---

Source: https://www.openparable.com/skill/devops-security/cis-bind9-v301-3-1 (OpenParable). Cite the canonical URL above.