| name | cis-bind9-v301-2-9 |
| description | Isolate BIND with chroot'ed Subdirectory (Automated) |
| category | cis-bind |
| version | 3.0.1 |
| author | cyberstrike-official |
| tags | ["cis","bind","dns","isc-bind","bind9","permissions-ownership"] |
| cis_id | 2.9 |
| cis_benchmark | CIS ISC BIND DNS Server 9.9 Benchmark v3.0.1 |
| tech_stack | ["bind","isc-bind","dns","linux"] |
| cwe_ids | [] |
| chains_with | [] |
| prerequisites | [] |
| severity_boost | {} |
CIS 2.9 — Isolate BIND with chroot'ed Subdirectory
Profile Applicability
- Level 1 - Authoritative Name Server
- Level 1 - Caching Only Name Server
Description
The chroot() system call causes an application to run with limited file system access so that a subdirectory becomes the root directory for the application environment. When this is done, the application is "jailed" and no longer has access to the entire file structure but is limited to the given subdirectory.
Rationale
Although there are ways that a chroot jail can be broken, most methods require that a process be running as root in order to escape. Since BIND should be run as a different user than root, a chroot is an effective defense, to limit access to sensitive system configuration files. In the event that BIND has a vulnerability that allows code execution, the attack will not have access to the real system files such as /etc/password, but will be limited to the files placed in the chroot subdirectory.
Impact
Not Applicable
Audit Procedure
Run the following two commands to find the root directory of the currently running named process. If the named process is chroot'ed, then the listing will show a symbolic link to the chroot subdirectory. If process is not chroot'ed, then the symbolic link will point to the real root directory /.
lrwxrwxrwx 1 named named 0 Sep 10 13:21 /proc/423/root -> /var/named/chroot
Remediation
Perform the following:
- Stop the named service and install the
bind-chroot package to provide the chroot directories.
- Edit the
/etc/sysconfig/named configuration file to have a line similar to the one shown below that sets the ROOTDIR environment variable.
ROOTDIR="/var/named/chroot"
- Move all the configuration files and any master zone files into their respective directions under the subdirectory
/var/named/chroot/