CVE-2021-35488 in Thruk
Summary
by MITRE • 11/10/2021
Thruk 2.40-2 allows /thruk/#cgi-bin/status.cgi?style=combined&title={TITLE] Reflected XSS via the host or title parameter. An attacker could inject arbitrary JavaScript into status.cgi. The payload would be triggered every time an authenticated user browses the page containing it.
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Analysis
by VulDB Data Team • 11/12/2021
The vulnerability CVE-2021-35488 affects Thruk version 2.40-2 and represents a reflected cross-site scripting flaw in the status.cgi component of the web interface. This security weakness resides within the handling of user-supplied input parameters, specifically the host and title parameters, which are processed through the combined style display mechanism. The vulnerability allows an attacker to inject malicious JavaScript code that gets executed in the context of authenticated user sessions when they navigate to the affected page.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the Thruk web application. When users access the status.cgi page with the style=combined parameter, the application fails to properly sanitize or encode the TITLE parameter value before rendering it in the HTML output. This creates an opportunity for attackers to craft malicious payloads that exploit the reflected XSS vulnerability. The attack vector specifically targets the host and title parameters, where the payload gets embedded directly into the web page content without adequate security controls.
The operational impact of this vulnerability is significant as it enables attackers to execute arbitrary JavaScript code within the context of authenticated user sessions. This means that any authenticated user who visits a page containing the malicious payload will have the code executed automatically, potentially leading to session hijacking, privilege escalation, or data exfiltration. The vulnerability affects all authenticated users of the Thruk monitoring system, making it particularly dangerous in environments where administrators and operators regularly access the status monitoring interface. The reflected nature of the vulnerability means that attackers can deliver payloads through various means such as email links, compromised web pages, or social engineering campaigns.
The vulnerability aligns with CWE-79 Cross-site Scripting and follows patterns identified in the ATT&CK framework under TA0001 Initial Access and TA0002 Execution. Organizations using Thruk should immediately implement mitigations including input validation, output encoding, and proper parameter sanitization. The recommended approach involves updating to the latest version of Thruk where this vulnerability has been patched, implementing web application firewalls to detect and block malicious payloads, and conducting security awareness training for users to recognize potential social engineering attempts. Additionally, organizations should consider implementing Content Security Policy headers to prevent execution of unauthorized scripts and establish proper access controls to limit exposure of vulnerable components within the monitoring infrastructure.