The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon does not allow compression or only allows compression after successful authentication.
An XCCDF Rule
Description
<VulnDiscussion>If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-204602r880758_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Uncomment the "Compression" keyword in "/etc/ssh/sshd_config" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor) on the system and set the value to "delayed" or "no":
Compression no
The SSH service must be restarted for changes to take effect.