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The Domain Name System (DNS) is one of the fundamental services of the Internet, and therefore companies usually allow the DNS protocol to pass bidirectionally through their firewall. This is necessary so that, for example, employees can call up external websites and customers or prospective customers are able to find the company's websites.
This offers the usual convenience of using the internet, but also opens up opportunities for potential attackers to infect a network.
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Since numerous DNS tunneling tools are offered for download on the Internet, DNS tunneling attacks can be carried out quite easily. Even inexperienced attackers are thus able to route data past the security devices of a network or, for example, to bypass the login to a (chargeable) WLAN hotspot without having to authenticate the requesting WLAN client.
As of LCOS 10.50 RC3REL, all DNS queries that pass through the LANCOM DNS forwarder are therefore subjected to a security check. This prevents data tunnels from being transported via DNS messages.
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