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
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.
- ID
- SV-204602r880758_rule
- Version
- RHEL-07-040470
- Severity
- Medium
- References
- Updated
Remediation Templates
A 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.