Rule Category

PROTOCOL-DNS -- Snort alerted on a Domain Name Server (DNS) protocol issue. These packets travel over UDP on port 53 to serve DNS queries--user website requests through a browser. Several vulnerability use-cases exist (ie, additional data could be sent with a request, which would contact a DNS server pre-prepared to send information back and forth).

Alert Message

PROTOCOL-DNS BIND DNS server TSIG denial of service attempt

Rule Explanation

The rule looks for evidence of a crafted DNS TSIG query intended to trigger an assertion failure in some versions of BIND servers.

What To Look For

This rule fires upon an attempted exploitation of CVE-2020-8617, a denial of service vulnerability in some versions of BIND servers.

Known Usage

No public information

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

MITRE ATT&CK Framework

Tactic: Impact

Technique: Service Stop

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

Additional Links

Rule Vulnerability

Denial of Service

Denial of Service attacks aim to make a server or program unresponsive for users. These attacks may be volume-based, to overwhelm the system, or they may use certain logical flaws in the software to cut the service off from the users. The attack may come from one or multiple sources. These attacks do not usually lead to a remote code execution. Volume based attacks are best handled using a firewall application.

CVE Additional Information