CVE-2018-19191 in Webmin
Summary
by MITRE
Webmin 1.890 has XSS via /config.cgi?webmin, the /shell/index.cgi history parameter, /shell/index.cgi?stripped=1, or the /webminlog/search.cgi uall or mall parameter.
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Analysis
by VulDB Data Team • 08/03/2023
The vulnerability identified as CVE-2018-19191 represents a critical cross-site scripting flaw affecting Webmin version 1.890, a widely used web-based system administration tool. This vulnerability exists across multiple endpoints within the Webmin interface, specifically targeting parameters that handle user input without proper sanitization or output encoding. The flaw allows attackers to inject malicious scripts into web pages viewed by other users, potentially enabling session hijacking, data theft, or unauthorized access to administrative functions. The affected parameters include the webmin parameter in config.cgi, the history parameter in shell/index.cgi, the stripped parameter in shell/index.cgi, and the uall or mall parameters in webminlog/search.cgi.
The technical exploitation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the Webmin application's codebase. When user-supplied data is directly incorporated into web page responses without proper sanitization, it creates an opening for attackers to execute malicious JavaScript code in the context of other users' browsers. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws where untrusted data is improperly integrated into web pages. The vulnerability demonstrates poor input handling practices that violate fundamental web security principles and can be exploited through various attack vectors depending on the specific endpoint targeted.
The operational impact of CVE-2018-19191 is significant for organizations relying on Webmin for system administration tasks. Attackers could leverage this vulnerability to establish persistent access to administrative interfaces, potentially leading to complete system compromise. The attack surface is broad as it affects multiple endpoints within the Webmin application, increasing the likelihood of successful exploitation. Depending on the attacker's goals, this vulnerability could enable unauthorized access to sensitive system information, modification of system configurations, or even privilege escalation within the administrative environment. The vulnerability directly impacts the integrity and confidentiality of system administration operations, as malicious scripts could capture user credentials or manipulate administrative functions.
Mitigation strategies for CVE-2018-19191 should focus on immediate patching of the Webmin application to version 1.891 or later, which contains the necessary fixes for the identified XSS vulnerabilities. Organizations should implement input validation and output encoding measures at multiple layers, including web application firewalls and server-side sanitization routines. Network segmentation and access controls should be reinforced to limit exposure to the affected Webmin interfaces. Security monitoring should be enhanced to detect unusual patterns in webminlog search queries or shell command executions that might indicate exploitation attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web applications. Additionally, implementing the principle of least privilege and regular credential rotation can help limit the potential damage from successful exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1059 technique for command and scripting interpreter, as exploitation often involves injecting malicious commands through the vulnerable web interfaces.