CVE-2024-11986 in CrushFTP
Summary
by MITRE • 12/13/2024
Improper input handling in the 'Host Header' allows an unauthenticated attacker to store a payload in web application logs. When an Administrator views the logs using the application's standard functionality, it enables the execution of the payload, resulting in Stored XSS or 'Cross-Site Scripting'.
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Analysis
by VulDB Data Team • 02/18/2025
This vulnerability represents a critical security flaw in web application input validation mechanisms that specifically targets the handling of HTTP Host headers. The issue stems from inadequate sanitization of user-supplied input within the application's logging infrastructure, creating a persistent security risk that can be exploited through improper input handling. The vulnerability falls under the category of improper input validation as defined by CWE-20, where the application fails to properly validate or sanitize input data before processing or storing it. The flaw manifests when an attacker crafts a malicious Host header containing executable script content that gets stored in the application's log files without proper escaping or encoding.
The technical execution of this vulnerability involves an attacker submitting a specially crafted Host header value that contains malicious script code within the web application's request processing pipeline. When the application processes this request and stores the Host header value in its logging system, the malicious payload becomes embedded within the log entries. The vulnerability's exploitation pathway follows a classic stored cross-site scripting pattern where the attacker's payload is not executed immediately but waits for an administrator or authorized user to view the logs through the application's standard administrative interface. This design creates a time-delayed attack vector that leverages the trust relationship between the application and its administrators who routinely access log files for system monitoring and maintenance purposes.
The operational impact of this vulnerability extends beyond simple script execution, as it represents a significant escalation of privileges and potential for further compromise. When administrators view the log files containing the malicious payload, their browsers execute the embedded scripts within the context of their privileged sessions, potentially allowing attackers to access sensitive administrative functions, extract confidential data, or perform unauthorized actions on behalf of the system. This attack vector aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566.001 for credential access through social engineering, as it relies on the administrator's routine behavior of reviewing logs. The vulnerability essentially transforms the application's logging functionality from a security monitoring tool into an attack surface that can be weaponized against system administrators.
The exploitation requires minimal privileges as the attacker only needs to send a malicious HTTP request to the vulnerable application, making this a particularly dangerous vulnerability for publicly accessible web applications. The attack is persistent and can remain active for extended periods until the logs are cleared or the application is patched, providing attackers with sustained access opportunities. Organizations should implement immediate mitigations including input sanitization of Host headers, proper encoding of log entries, and regular review of log file content for suspicious patterns. The vulnerability demonstrates the critical importance of validating all user-supplied input across all application components, particularly those that may be displayed in administrative interfaces. Regular security testing and input validation reviews should be conducted to identify similar flaws in other application components that may serve as attack vectors for similar stored XSS vulnerabilities.