The SSH daemon must be configured to only use the SSHv2 protocol.

From Oracle Linux 5 Security Technical Implementation Guide

Associated with: CCI-001436

SV-63543r1_rule The SSH daemon must be configured to only use the SSHv2 protocol.

Vulnerability discussion

SSHv1 is not a DoD-approved protocol and has many well-known vulnerability exploits. Exploits of the SSH daemon could provide immediate root access to the system.

Check content

Locate the sshd_config file: # more /etc/ssh/sshd_config Examine the file. If the variables 'Protocol 2,1' or 'Protocol 1' are defined on a line without a leading comment, this is a finding. If the SSH server is F-Secure, the variable name for SSH 1 compatibility is 'Ssh1Compatibility', not 'protocol'. If the variable 'Ssh1Compatiblity' is set to 'yes', then this is a finding.

Fix text

Edit the sshd_config file and set the "Protocol" setting to "2". If using the F-Secure SSH server, set the "Ssh1Compatibility" setting to "no". Restart the SSH daemon. # /sbin/service sshd restart

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