What is DNS tunneling over TCP?
DNS Tunneling is a method of cyber attack that encodes the data of other programs or protocols in DNS queries and responses. DNS tunneling enables these cybercriminals to insert malware or pass stolen information into DNS queries, creating a covert communication channel that bypasses most firewalls.
Is it safe to open port 53?
If only use your local network, use a local nameserver and have no connection to random sites on the Internet then you do not need to leave port 53 open. But if you do want to use the Internet then you need to be able to translate hostnames to IP addresses. For that you need DNS.
How does tunneling data over DNS bypass firewalls?
Tunneling Data and Commands Over DNS to Bypass Firewalls. No matter how tightly you restrict outbound access from your network, you probably allow DNS queries to at least one server. Adversaries can abuse this “hole” in your firewall to exfiltrate data and establish stealthy Command and Control (C2) channels that are very difficult to block.
Is there such a thing as DNS tunneling?
IP-Over-DNS Tunneling — This sounds crazy, but there are utilities that have implemented the IP stack on the DNS query-response protocol. That would make it relatively easy to transfer data using standard communications software like FTP, Netcat, ssh, etc. Powerfully evil!
How does tunneling work with dnscat2 server?
The tunneling approach implemented by dnscat2 involves an attacker-controlled system running dnscat2 server software. This Internet-accessible host listens for specially-formulated DNS queries the dnscat2 client component issues from the victim’s environment to transmit data or obtain instructions.
How is DNS tunneling used by malicious actors?
On top of the examples of DNS use mentioned already, a number of tools exist that can enable, amongst other things, their attackers to create covert channels over DNS for the purposes of hiding communication or bypassing policies put in place by network administrators.