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).
PROTOCOL-DNS HAProxy dns_read_name compressed name denial of service attempt
This rule checks for value that leads to recursively points to itself and cause a loop with unreachable exit condition
This rule alerts on return exploit traffic
No public information
Known false positives, with the described conditions
NA
Cisco Talos Intelligence Group
MITRE::ATT&CK Framework::Enterprise::Impact::Endpoint Denial of Service::Application or System Exploitation
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-2018-20103An issue was discovered in dns.c in HAProxy through 1.8.14. In the case of a compressed pointer, a crafted packet can trigger infinite recursion by making the pointer point to itself, or create a long chain of valid pointers resulting in stack exhaustion. |
|
||||||||||||||||||||||||||||||
MITRE TTP | T1499.004 Application or System Exploitation |
|---|---|
| MITRE ID | T1499.004 |
| Tactic | Impact |
| Technique | Endpoint Denial of Service |
| Subtechnique | Application or System Exploitation |
| Description | Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users. Some systems may automatically restart critical applications and services when crashes occur, but they can likely be re-exploited to cause a persistent DoS condition. |
©2025 Cisco and/or its affiliates. Snort, the Snort and Pig logo are registered trademarks of Cisco. All rights reserved.
