The SSH client must be configured to not use CBC-based ciphers.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| GEN005511-ESXI5-701 | GEN005511-ESXI5-701 | GEN005511-ESXI5-701_rule | Medium |
| Description |
|---|
| The Cipher-Block Chaining (CBC) mode of encryption as implemented in the SSHv2 protocol is vulnerable to chosen plain text attacks and must not be used. |
| STIG | Date |
|---|---|
| VMware ESXi v5 Security Technical Implementation Guide | 2013-01-15 |
Details
| Check Text ( C-GEN005511-ESXI5-701_chk ) |
|---|
| Disable lock down mode. Enable the ESXi Shell. Check the SSH client configuration for allowed ciphers. # grep -i ciphers /etc/ssh/ssh_config | grep -v '^#' Re-enable lock down mode. If no lines are returned, or the returned ciphers list contains any cipher ending with cbc, this is a finding. |
| Fix Text (F-GEN005511-ESXI5-701_fix) |
|---|
| Disable lock down mode. Enable the ESXi Shell. Edit the SSH client configuration and add/modify the "Ciphers" configuration. # vi /etc/ssh/ssh_config Re-enable lock down mode. |