The SSH daemon must limit connections to a single session.

From VMware ESXi Server 5.0 Security Technical Implementation Guide

Associated with: CCI-000054

SV-51069r2_rule The SSH daemon must limit connections to a single session.

Vulnerability discussion

The SSH protocol has the ability to provide multiple sessions over a single connection without reauthentication. A compromised client could use this feature to establish additional sessions to a system without consent or knowledge of the user.

Check content

Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # grep MaxSessions /etc/ssh/sshd_config If the command returns nothing, or if "MaxSessions" is not set to "1", this is a finding. Re-enable lock down mode.

Fix text

Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # vi /etc/ssh/sshd_config Add/modify the attribute line entry to the following (quotes for emphasis only): "MaxSessions 1" Re-enable lock down mode.

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