# Cis Bind V100 8 7

> Cis Bind V100 8 7 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.

Ensure Signing Keys are Unique (Automated)

- Skill name: `cis-bind-v100-8-7`
- 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_9.11_Benchmark_v1.0.0/cis-bind-v100-8-7/SKILL.md
- Repository: CyberStrikeus/CyberStrike (1,211 GitHub stars when collected)

## SKILL.md

# CIS 8.7 — Ensure Signing Keys are Unique

## Profile Applicability

- Authoritative Name Server Level 2

## Description

Each zone should have a unique Zone Signing Keys (ZSK) and a unique Key Signing Keys (KSK) that is different from all other keys.

## Rationale

The ZSK key typically has a shorter expiration date then the KSK, and should be unique from the KSK as well as keys used for other zones. If a private key is compromised, the damage is limited to unique key that was disclosed, rather the compromising multiple zones.

## Impact

Not specified.

## Audit Procedure

To verify each key is unique, and has unique zone usage, perform the following:

- The sample command below will extract the public keys from the key files and count the number of occurrences of each key value

```
# find $KEYDIR -name '*.key' |  xargs grep -ho 'DNSKEY .*' | sort | uniq -c
```

The count occurrences preceding each key should be one in the output.

- To find the file names of duplicates key values, reuse the find command, but have the grep command report the file names for a given key value. For example:

```
# find $KEYDIR -name '*.key' |  xargs  grep -l ' <key value>
```

## Remediation

To remediate a duplicate key, perform the following:

- Generate a new key to replace the duplicate key using dnssec-keygen and one of the recommended algorithms. An example command is shown below:

```
# dnssec-keygen -a ECDSAP256SHA256 example.org
```

- Implement a rollover period to phase out the duplicate key and replace it with the the newly generated key.
- Once the key is fully deleted from the active use, remove the file.

## Default Value

Not specified.

## References

None listed in benchmark.

## CIS Controls

| Controls Version | Control | IG 1 | IG 2 | IG 3 |
| ---------------- | ------- | ---- | ---- | ---- |
| v7               | N/A     | N    | N    | N    |

## MITRE ATT&CK Mappings

| Tactic            | Technique                   |
| ----------------- | --------------------------- |
| Credential Access | T1552 Unsecured Credentials |

## Profile

- Level 2 - Authoritative Name Server

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Source: https://www.openparable.com/skill/devops-security/cis-bind-v100-8-7 (OpenParable). Cite the canonical URL above.