Title

The SSH daemon must not allow rhosts RSA authentication. (Cat II impact)

Discussion

If SSH permits rhosts RSA authentication, a user may be able to login based on the keys of the host originating the request and not any user-specific authentication..

Check Content

Check the SSH daemon configuration. Note that keywords are case-insensitive and arguments (args) are case-sensitive. keyword=RhostsRSAAuthentication arg(s)=no Default values include: "no" Note: When the default "arg" value exactly matches the required "arg" value (see above), the <keyword=arg> entry is not required to exist (commented or uncommented) in the ssh (client) or sshd (server) configuration file. While not required, it is recommended that the configuration file(s) be populated with all keywords and assigned arg values as a means to explicitly document the ssh(d) binary's expected behavior. Examine the file. # cat /opt/ssh/etc/sshd_config | tr '\011' ' ' | tr -s ' ' | sed -e 's/^[ \t]*//' | grep -v '^#' | grep -i "RhostsRSAAuthentication" This option currently applies only to Protocol Version 1. If using Protocol 1 or any variant of Protocol 1, IE: Protocol 1,2 OR Protocol 2,1 and configuration information is not returned or the return value is yes, this is a finding. If using Protocol 2, this is Not Applicable (NA).

Fix Text

Edit the SSH daemon configuration and add or edit the RhostsRSAAuthentication setting value to no. Note that the above guidance applies exclusively to Protocol(s) 1/1,2/2,1 only. If using Protocol 2 only, the check is not applicable and further action is not required.

Additional Identifiers

Rule ID: SV-35142r1_rule

Vulnerability ID: V-22487

Group Title: GEN005538

Expert Comments

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