How does a Cisco Secure Firewall help to lower the risk of exfiltration techniques that steal customer data?

Blocking UDP port 53 would prevent legitimate DNS resolution for most internet communications, disrupting normal network operations rather than specifically targeting data exfiltration within DNS. This is too broad and disruptive.

Blocking TCP port 53 would prevent legitimate DNS zone transfers and might affect some specific DNS services, but it is not a primary mechanism to detect and stop data exfiltration embedded within standard DNS queries and responses.

Data exfiltration often utilizes DNS tunneling techniques where malicious actors embed stolen data within legitimate-looking DNS queries or responses. A Cisco Secure Firewall, equipped with deep packet inspection and advanced threat capabilities, can analyze the content of DNS traffic to detect and block these covert exfiltration channels.

Encrypting DNS communication, such as DNS over HTTPS (DoH) or DNS over TLS (DoT), makes it difficult for a firewall to inspect the DNS payload for malicious content, thereby hindering the detection of DNS-based exfiltration rather than lowering its risk through inspection.