CVE-2021-32746 in Web
Summary
by MITRE • 07/13/2021
Icinga Web 2 is an open source monitoring web interface, framework and command-line interface. Between versions 2.3.0 and 2.8.2, the `doc` module of Icinga Web 2 allows to view documentation directly in the UI. It must be enabled manually by an administrator and users need explicit access permission to use it. Then, by visiting a certain route, it is possible to gain access to arbitrary files readable by the web-server user. The issue has been fixed in the 2.9.0, 2.8.3, and 2.7.5 releases. As a workaround, an administrator may disable the `doc` module or revoke permission to use it from all users.
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Analysis
by VulDB Data Team • 07/15/2021
The vulnerability CVE-2021-32746 affects Icinga Web 2, a widely-used open source monitoring web interface that serves as both a framework and command-line interface for system and network monitoring operations. This monitoring solution is deployed across enterprise environments where it provides critical visibility into infrastructure health and performance metrics. The affected component is the `doc` module which was designed to allow administrators to view documentation directly within the user interface, enhancing usability for monitoring personnel who need quick access to help resources while managing their systems. The module requires manual activation by administrators and users must possess explicit permissions to access it, creating a controlled access environment that should have prevented unauthorized file access.
The technical flaw resides in the improper input validation and path traversal handling within the documentation module's file access functionality. When users navigate to specific routes within the `doc` module, the application fails to properly sanitize user-provided input that determines which documentation files to display. This vulnerability enables attackers to craft malicious requests that bypass normal file access controls and gain access to arbitrary files on the web server filesystem that are readable by the web server user account. The issue represents a classic path traversal vulnerability where insufficient validation allows attackers to manipulate file paths and access sensitive data that should remain protected. This weakness falls under CWE-22 Path Traversal and aligns with ATT&CK technique T1083 File and Directory Discovery, as it enables unauthorized enumeration of the filesystem.
The operational impact of this vulnerability is significant for organizations using Icinga Web 2, particularly those with multiple users who have access to the documentation module. An attacker who gains access to this module could potentially read sensitive configuration files, log files, or other documentation that might contain system information, credentials, or architectural details that could aid in further attacks. The vulnerability affects versions between 2.3.0 and 2.8.2, representing a substantial portion of the user base that would have been exposed to this risk. Organizations with extensive monitoring deployments using Icinga Web 2 could face serious security implications if attackers exploit this vulnerability to access internal documentation or configuration artifacts that may contain sensitive operational information.
The vulnerability has been addressed in patched releases including version 2.9.0, 2.8.3, and 2.7.5, which implement proper input sanitization and file access controls within the documentation module. These patches ensure that user-provided paths are properly validated and that only authorized documentation files can be accessed through the module interface. For organizations unable to immediately apply these patches, administrative workarounds are available including disabling the `doc` module entirely or revoking access permissions for all users. These mitigation strategies align with ATT&CK tactic TA0005 Defense Evasion and TA0003 Persistence, as they prevent the exploitation vector while maintaining operational security. Organizations should also consider implementing additional security controls such as web application firewalls, access control reviews, and regular security assessments to prevent similar vulnerabilities in other monitoring tools and web applications within their infrastructure.