Red Hat Security Advisory: Red Hat OpenStack Platform 17.1 (python-paramiko) security update
🔗 CVE IDs covered (1)
📋 Description
CVE-2023-48795 — ssh: Prefix truncation attack on Binary Packet Protocol (BPP)
🎯 Affected products3
- Red Hat OpenStack Platform 17.1
- python-paramiko-0:2.11.0-2.el9ost.src as a component of Red Hat OpenStack Platform 17.1
- python3-paramiko-0:2.11.0-2.el9ost.noarch as a component of Red Hat OpenStack Platform 17.1
✅ Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: Update to the last version and check that client and server provide kex pseudo-algorithms indicating usage of the updated version of the protocol which is protected from the attack. If "[email protected]" is provided by clients and "[email protected]" is in the server's reply, no other steps are necessary. Disabling ciphers if necessary: If "[email protected]" is not provided by clients or "[email protected]" is absent in the server's reply, you can disable the following ciphers and HMACs as a workaround on RHEL-8 and RHEL-9: 1. [email protected] 2. [email protected] 3. [email protected] 4. [email protected] 5. [email protected] To do that through crypto-policies, one can apply a subpolicy with the following content: ``` cipher@SSH = -CHACHA20-POLY1305 ssh_etm = 0 ``` e.g., by putting these lines into `/etc/crypto-policies/policies/modules/CVE-2023-48795.pmod`, applying the resulting subpolicy with `update-crypto-policies --set $(update-crypto-policies --show):CVE-2023-48795` and restarting openssh server. One can verify that the changes are in effect by ensuring the ciphers listed above are missing from both `/etc/crypto-policies/back-ends/openssh.config` and `/etc/crypto-policies/back-ends/opensshserver.config`. For more details on using crypto-policies, please refer to https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/security_hardening/using-the-system-wide-cryptographic-policies_security-hardening Note that this procedure does limit the interoperability of the host and is only suggested as a temporary mitigation until the issue is fully resolved with an update. For RHEL-7: We can recommend to use strict MACs and Ciphers on RHEL7 in both files /etc/ssh/ssh_config and /etc/ssh/sshd_config. Below strict set of Ciphers and MACs can be used as mitigation for RHEL 7. ``` Ciphers aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] MACs [email protected],[email protected],hmac-sha2-256,hmac-sha2-512 ``` - For Openshift Container Platform 4: Please refer the KCS[1] document for verifying the fix in RHCOS. [1] https://access.redhat.com/solutions/7071748