CVE-2017-16160 in 11xiaoli
Summary
by MITRE
11xiaoli is a simple file server. 11xiaoli is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url.
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Analysis
by VulDB Data Team • 02/16/2020
The vulnerability identified as CVE-2017-16160 affects 11xiaoli, a straightforward file server implementation that suffers from a critical directory traversal flaw. This issue stems from inadequate input validation within the application's URL parsing mechanism, allowing malicious actors to exploit the system by manipulating file paths through the use of relative path traversal sequences such as "../". The vulnerability resides in the server's failure to properly sanitize user-supplied input before processing file requests, creating a direct pathway for unauthorized access to the underlying filesystem. This type of vulnerability is classified under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw enables attackers to navigate beyond the intended directory boundaries and access files that should remain restricted, potentially exposing sensitive data, configuration files, or even system binaries.
The operational impact of this directory traversal vulnerability is significant and multifaceted. An attacker exploiting this weakness can retrieve arbitrary files from the server's filesystem, potentially gaining access to sensitive information such as user credentials, application configuration files, database contents, or system-level files. The vulnerability allows for recursive directory traversal through multiple "../" sequences, amplifying the attack scope and potentially enabling complete system compromise. This weakness directly maps to several techniques described in the MITRE ATT&CK framework under the T1083 - File and Directory Discovery tactic, where adversaries seek to identify files and directories on compromised systems. The vulnerability also aligns with T1566 - Phishing with Malicious Attachments, as attackers may use this flaw to harvest sensitive data from exposed file servers.
Mitigation strategies for CVE-2017-16160 should focus on implementing robust input validation and sanitization measures within the 11xiaoli application. The most effective approach involves normalizing all user-supplied paths by removing or encoding special characters such as "../" sequences before processing file requests. Implementing a whitelist-based approach that only allows access to predetermined directories and files can significantly reduce the attack surface. Additionally, the application should enforce strict path validation that prevents any attempt to traverse above the designated root directory. Security measures should include regular input sanitization, proper access controls, and implementation of secure coding practices that prevent path traversal vulnerabilities. Organizations should also consider implementing network-level protections such as web application firewalls that can detect and block suspicious path traversal attempts. The remediation process should include thorough code review to ensure all file access operations properly validate and sanitize input parameters, as well as implementing proper logging mechanisms to detect potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other applications and services that may be susceptible to the same class of attack.