Title

The read and write access to a TSIG key file used by a BIND 9.x server must be restricted to only the account that runs the name server software. (Cat II impact)

Discussion

Weak permissions of a TSIG key file could allow an adversary to modify the file, thus defeating the security objective.

Check Content

Verify permissions assigned to the TSIG keys enforce read-write access to the key owner and deny access to group or system users: With the assistance of the DNS Administrator, determine the location of the TSIG keys used by the BIND 9.x implementation: # ls –al <TSIG_Key_Location> -rw-------. 1 named named 76 May 10 20:35 tsig-example.key If the key files are more permissive than 600, this is a finding.

Fix Text

Change the permissions of the TSIG key files: # chmod 600 <TSIG_key_file>

Additional Identifiers

Rule ID: SV-207565r879613_rule

Vulnerability ID: V-207565

Group Title: SRG-APP-000176-DNS-000019

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.