CVE-2018-3771 in statics-server
Summary
by MITRE
An XSS in statics-server <= 0.0.9 can be used via injected iframe in the filename when statics-server displays directory index in the browser.
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Analysis
by VulDB Data Team • 03/09/2020
The vulnerability identified as CVE-2018-3771 represents a cross-site scripting flaw within the statics-server web application version 0.0.9 and earlier. This issue manifests when the application displays directory indexes in web browsers, creating a potential attack vector through maliciously crafted iframe injections in filename parameters. The vulnerability stems from insufficient input validation and sanitization of user-supplied data, specifically within the filename handling mechanism that generates directory listings. When users browse directories served by statics-server, the application fails to properly escape or filter special characters in filenames, allowing attackers to inject malicious script code that executes in the context of the victim's browser.
The technical exploitation of this vulnerability occurs through the manipulation of filename parameters within the directory index display functionality. Attackers can craft filenames containing embedded iframe tags or other malicious scripts that get rendered as part of the directory listing page. When a victim accesses the affected directory, the browser executes the injected code, potentially leading to session hijacking, credential theft, or redirection to malicious sites. This vulnerability directly maps to CWE-79 which defines Cross-Site Scripting as the injection of malicious code into web applications, and more specifically aligns with CWE-80 which addresses improper neutralization of script-related HTML tags. The flaw operates at the application layer where user input is not properly sanitized before being rendered in the browser context.
The operational impact of CVE-2018-3771 extends beyond simple script execution, as it enables attackers to establish persistent malicious presence within environments where statics-server is deployed. Organizations using this software in development or staging environments may experience unauthorized access to sensitive files, data exfiltration, or the establishment of command and control channels. The vulnerability is particularly concerning in environments where multiple users access shared directories, as a single compromised filename can affect all users viewing the directory listing. From an ATT&CK framework perspective, this vulnerability corresponds to T1059.007 for Scripting and T1566.001 for Phishing, as attackers can leverage the XSS to deliver malicious payloads and establish initial access points. The vulnerability also relates to T1071.004 for Application Layer Protocol, since it affects web-based file serving applications.
Mitigation strategies for CVE-2018-3771 should prioritize immediate software updates to versions that address the XSS vulnerability, as the maintainers have likely released patches for this specific issue. Organizations should implement input validation and sanitization measures that escape special characters in filenames before rendering them in directory listings, particularly focusing on HTML tags and script elements. The application should employ proper content security policies to prevent script execution, and implement proper output encoding for all user-supplied data displayed in web contexts. Additionally, network-level protections such as web application firewalls can provide additional defense-in-depth measures. Security teams should conduct thorough vulnerability assessments to identify all instances of statics-server installations and ensure comprehensive patch management across all affected systems. Regular security testing including dynamic application security testing and manual code review should be implemented to prevent similar vulnerabilities from being introduced in future development cycles.