CVE-2017-16147 in shit-server
Summary
by MITRE
shit-server is a file server. shit-server 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-2017-16147 affects shit-server, a file server implementation that suffers from a critical directory traversal flaw. This weakness allows malicious actors to access arbitrary files on the underlying filesystem by manipulating URL parameters through the strategic insertion of "../" sequences. The vulnerability represents a fundamental failure in input validation and path handling within the server's request processing logic. Such directory traversal vulnerabilities are 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 attack vector exploits the server's inability to properly sanitize user-supplied input before using it to construct file paths, creating an opportunity for unauthorized access to sensitive system resources.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious URLs containing directory traversal sequences that bypass normal file access controls. When the server processes these requests, it interprets the "../" components as requests to navigate up the directory hierarchy, potentially allowing access to files outside the intended web root or serving directory. This flaw fundamentally undermines the server's security model by enabling attackers to read system files, configuration data, or other sensitive resources that should remain protected from remote access. The vulnerability is particularly dangerous because it can be exploited through simple HTTP requests without requiring authentication or specialized tools, making it highly accessible to attackers of varying skill levels.
The operational impact of CVE-2017-16147 extends beyond simple unauthorized file access to encompass potential system compromise and data exfiltration capabilities. An attacker who successfully exploits this vulnerability could gain access to sensitive information such as database credentials, application configuration files, system logs, or even system binaries. The severity of this exposure depends on the server's configuration and the privileges under which it operates, but typically results in a complete compromise of the file serving functionality and potentially broader system access. This vulnerability aligns with ATT&CK technique T1083, which describes discovery of file and directory permissions, and T1566, which covers credential access through exploitation of vulnerabilities in network services. Organizations running affected versions of shit-server face significant risk of data breaches, compliance violations, and potential regulatory penalties.
Mitigation strategies for CVE-2017-16147 require immediate action to address the core path traversal vulnerability. The most effective approach involves implementing robust input validation and sanitization mechanisms that prevent directory traversal sequences from being processed as part of file paths. This includes implementing proper path normalization, rejecting requests containing "../" or similar traversal patterns, and ensuring that all file access operations occur within designated safe directories. Organizations should also consider implementing additional security controls such as web application firewalls that can detect and block malicious traversal attempts, regular security audits of file serving components, and privilege separation to limit the damage that could result from successful exploitation. The vulnerability demonstrates the critical importance of validating all user input and implementing defense-in-depth strategies to protect against common web application vulnerabilities that have been well-documented and widely exploited over many years.