Successful/unsuccessful uses of the ssh-keysign command must generate an audit record.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-75707	UBTU-16-020410	SV-90387r3_rule		Medium

Description
Reconstruction of harmful events or forensic analysis is not possible if audit records do not contain enough information. At a minimum, the organization must audit the full-text recording of privileged ssh commands. The organization must maintain audit trails in sufficient detail to reconstruct events to determine the cause and impact of compromise. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

Description

Reconstruction of harmful events or forensic analysis is not possible if audit records do not contain enough information. At a minimum, the organization must audit the full-text recording of privileged ssh commands. The organization must maintain audit trails in sufficient detail to reconstruct events to determine the cause and impact of compromise. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215

STIG	Date
Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide	2018-07-18

Details

Check Text ( C-75393r2_chk )
Verify the Ubuntu operating system generates an audit record when successful/unsuccessful attempts to use the "ssh-keysign" command occur. Check that the following calls are being audited by performing the following command to check the file system rules in "/etc/audit/audit.rules": # sudo grep ssh-keysign /etc/audit/audit.rules -a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=4294967295 -k privileged-ssh If the command does not return a line, or the line is commented out, this is a finding.

Check Text ( C-75393r2_chk )

Verify the Ubuntu operating system generates an audit record when successful/unsuccessful attempts to use the "ssh-keysign" command occur.

Check that the following calls are being audited by performing the following command to check the file system rules in "/etc/audit/audit.rules":

# sudo grep ssh-keysign /etc/audit/audit.rules

-a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=4294967295 -k privileged-ssh

If the command does not return a line, or the line is commented out, this is a finding.

Fix Text (F-82335r2_fix)
Configure the audit system to generate an audit event for any successful/unsuccessful use of the "ssh-keysign" command. Add or update the following rules in the "/etc/audit/audit.rules" file: -a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=4294967295 -k privileged-ssh The audit daemon must be restarted for the changes to take effect. To restart the audit daemon, run the following command: # sudo systemctl restart auditd.service

Fix Text (F-82335r2_fix)

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "ssh-keysign" command.

Add or update the following rules in the "/etc/audit/audit.rules" file:

-a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=4294967295 -k privileged-ssh

The audit daemon must be restarted for the changes to take effect. To restart the audit daemon, run the following command:

# sudo systemctl restart auditd.service