Cis Bind V100 2 5

---
name: cis-bind-v100-2-5
description: "Set root Ownership of BIND Configuration Files (Automated)"
category: cis-bind
version: "1.0"
author: cyberstrike-official
tags: [cis, bind, dns, isc-bind, bind9, permissions-ownership]
cis_id: "2.5"
cis_benchmark: "CIS ISC BIND DNS Server 9.11 Benchmark v1.0.0"
tech_stack: [bind, isc-bind, dns, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# CIS 2.5 — Set root Ownership of BIND Configuration Files

## Profile Applicability

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

## Description

The configuration files in the ISC BIND directories should be owned by root. Of course, any files created at run time by BIND, such as `pid` files, log files and slave zone files will necessarily be owned by named.

## Rationale

Restricting ownership of the configuration files provides defense in depth and will reduce the probability of unauthorized modifications to those important files. If there was a BIND vulnerability that allowed code execution as the named user, then the code would not be able modify the configuration files.

## Impact

Not specified.

## Audit Procedure

Run the command below to ensure that all BIND configuration files are owned by root, except for those found in the run-time directories. Ensure that the BIND benchmark variables used below are set as described in the benchmark overview, as these variables identify the run-time directories. (`$DYNDIR`, `$SLAVEDIR`, `$DATADIR`, `$RUNDIR`, `$LOGDIR`, `$TMPDIR`) If a `chroot`'ed directory is not used, then `$LOGDIR` and `$TMPDIR` are not generally a subdirectory of `$BIND_HOME`, and the two directories may be omitted, however including them will not cause any errors or false positives.

```bash
# find $BIND_HOME -type f \! -user root | egrep -v \
\^$DYNDIR\|\^$SLAVEDIR\|\^$DATADIR\|\^$RUNDIR\|\^$LOGDIR\|\^$TMPDIR
```

There should be no files listed in the output from the find command.

## Remediation

Perform the following:

- Capture the output of the previous audit command to a file named `nonroot-files.txt` and review any files not owned by root to ensure the files are necessary and are not expected run-time files. Delete any unnecessary files, and ensure any run-time files are being created in the appropriate run-time directory.

```bash
# find $BIND_HOME -type f \! -user root | egrep -v \
\^$DYNDIR\|\^$SLAVEDIR\|\^$DATADIR\|\^$RUNDIR\|\^$LOGDIR\|\^$TMPDIR > \
$TMPDIR/nonroot-files.txt
```

- The remaining non-run-time files should be changed to be owned by root, with a command like the following:

```bash
\# cat $TMPDIR/nonroot-files.txt | xargs chown root
\# rm $TMPDIR/nonroot-files.txt
```

## Default Value

The default rpm has the following configuration files owned by named.

- /var/named/named.ca
- /var/named/named.empty
- /var/named/named.localhost
- /var/named/named.loopback

## References

None listed.

## CIS Controls

| Controls Version | Control                                               | IG 1 | IG 2 | IG 3 |
| ---------------- | ----------------------------------------------------- | ---- | ---- | ---- |
| v6               | 14.4 Protect Information With Access Control Lists    | N    | Y    | Y    |
| v7               | 14.6 Protect Information through Access Control Lists | Y    | Y    | Y    |

## MITRE ATT&CK Mappings

| Tactic          | Technique                                         |
| --------------- | ------------------------------------------------- |
| Defense Evasion | T1222 File and Directory Permissions Modification |
| Persistence     | T1574 Hijack Execution Flow                       |

## Profile

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