CVE-2023-23549 in Checkmk
Summary
by MITRE • 11/15/2023
Improper Input Validation in Checkmk <2.2.0p15, <2.1.0p37, <=2.0.0p39 allows priviledged attackers to cause partial denial of service of the UI via too long hostnames.
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Analysis
by VulDB Data Team • 07/24/2024
CVE-2023-23549 represents a critical input validation vulnerability affecting Checkmk monitoring software versions prior to specific patches. This flaw resides in the system's handling of hostname inputs within the user interface, where insufficient validation allows malicious actors with privileged access to exploit the weakness. The vulnerability specifically targets the web-based administrative interface, making it particularly dangerous for environments where multiple administrators have access to the monitoring platform. The improper input validation stems from inadequate length checking mechanisms that fail to properly sanitize or limit the maximum allowable hostname length, creating a pathway for attackers to manipulate the system's input processing. This vulnerability operates under the broader category of CWE-20 Improper Input Validation, which encompasses various flaws related to insufficient validation of input data. The attack vector requires privileged access, meaning that an attacker must already have administrative credentials or equivalent privileges within the Checkmk environment to execute the exploit effectively. The operational impact manifests as partial denial of service specifically targeting the user interface components, rendering portions of the monitoring platform inaccessible to legitimate users. This disruption can severely impact system monitoring capabilities, potentially leading to missed alerts, delayed incident response, and overall degradation of operational visibility. The vulnerability is particularly concerning in enterprise environments where Checkmk serves as a critical infrastructure monitoring tool, as it can compromise the availability of essential administrative functions. From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1210 Exploitation of Remote Services, where attackers leverage weaknesses in application input handling to disrupt service availability. The specific nature of the flaw makes it challenging to detect through standard security scanning tools, as it requires specific input manipulation to trigger the denial of service condition. The patched versions of Checkmk address this issue through enhanced input validation that properly enforces hostname length limits and implements more robust sanitization routines for all user-provided data. Organizations should immediately apply the relevant security patches to mitigate this risk, particularly in environments where privileged access is not strictly controlled or where multiple administrators have access to the monitoring platform. The vulnerability demonstrates the importance of implementing comprehensive input validation across all user-facing interfaces, as even seemingly benign input fields can become attack vectors when not properly secured. Security teams should also consider implementing additional monitoring for unusual hostname inputs or patterns that might indicate attempted exploitation of similar validation weaknesses. The impact extends beyond immediate service disruption to potentially affecting business continuity, as monitoring system outages can lead to undetected infrastructure issues and delayed response to actual security incidents. Organizations using older Checkmk versions should prioritize upgrading to supported releases that include the patched validation mechanisms, while also reviewing their access control policies to minimize the risk of unauthorized privileged access to monitoring systems. This vulnerability reinforces the principle that input validation must be implemented at multiple layers of application architecture, including both client-side and server-side processing, to provide comprehensive protection against various attack vectors.