The Cisco ASA must be configured to filter inbound traffic on all external interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-239865 | CASA-FW-000230 | SV-239865r991797_rule | CCI-002403 | medium |
| Description | ||||
| Unrestricted traffic to the trusted networks may contain malicious traffic that poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a network, which uses bandwidth and other resources. Firewall filters control the flow of network traffic, ensure the flow of traffic is only allowed from authorized sources to authorized destinations. Networks with different levels of trust (e.g., the Internet) must be kept separated. | ||||
| STIG | Date | |||
| Cisco ASA Firewall Security Technical Implementation Guide | 2024-06-06 | |||
Details
Check Text (C-239865r991797_chk)
Review the ASA configuration to verify that it is filtering inbound traffic on all external interfaces.
access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.2 eq www
access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.2 eq https
access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.3 eq ftp
access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.3 eq ftp-data
access-list OUTSIDE_2_DMZ extended deny ip any any log
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access-group OUTSIDE_2_DMZ in interface OUTSIDE
If the ASA is not configured to filter inbound traffic on all external interfaces, this is a finding.
Fix Text (F-43057r665880_fix)
Step 1: Configure the ACL to allow specific inbound traffic.
ASA(config)# access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.2 eq www
ASA(config)# access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.2 eq https
ASA(config)# access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.3 eq ftp
ASA(config)# access-list OUTSIDE_2_DMZ extended permit tcp any host 10.1.33.3 eq ftp-data
ASA(config)# access-list OUTSIDE_2_DMZ extended deny ip any any log
Step 2: Apply the ACL inbound to the external interface.
ASA(config)# access-group OUTSIDE_2_DMZ in interface OUTSIDE