CVE-2017-16179 in dasafio
Summary
by MITRE
dasafio is a web server. dasafio is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url. File access is restricted to only .html files.
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Analysis
by VulDB Data Team • 02/16/2020
The CVE-2017-16179 vulnerability affects dasafio, a web server implementation that suffers from a critical directory traversal flaw. This vulnerability stems from inadequate input validation within the web server's URL parsing mechanism, allowing remote attackers to manipulate file paths through crafted requests containing directory traversal sequences. The flaw specifically enables attackers to navigate beyond the intended web root directory and access arbitrary files on the underlying filesystem. This type of vulnerability falls under the Common Weakness Enumeration category CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The security implications of this vulnerability are significant as it allows unauthorized access to sensitive files that may contain configuration data, user credentials, application source code, or other confidential information. The vulnerability operates by interpreting the "../" sequences in URLs as directory navigation commands, effectively bypassing normal file access controls and allowing attackers to traverse the filesystem hierarchy.
The operational impact of CVE-2017-16179 extends beyond simple file access, as it provides attackers with the ability to potentially discover and retrieve sensitive system information. Even though the description indicates that file access is restricted to .html files, this limitation does not prevent attackers from discovering other sensitive files that might be accessible through different means or from using the vulnerability to map the filesystem structure. The attack vector is particularly dangerous because it requires minimal effort to exploit, often allowing attackers to gain access to system files, configuration parameters, or even application source code that could reveal additional vulnerabilities. The vulnerability aligns with ATT&CK technique T1083, which describes discovering file and directory permissions on compromised systems, as attackers can use directory traversal to enumerate available files and potentially identify privileged resources. The restricted access to .html files suggests that the web server may be configured with specific restrictions, but these protections are easily bypassed through simple path manipulation.
Mitigation strategies for CVE-2017-16179 should focus on implementing robust input validation and sanitization mechanisms within the web server's request processing pipeline. The most effective immediate solution involves implementing strict path validation that prevents directory traversal sequences from being processed, regardless of their position within the URL. This can be achieved through proper input filtering, canonicalization of file paths, and ensuring that all file access operations are performed within a designated safe directory. Organizations should implement proper access controls and file permission settings to limit what files can be accessed even if the vulnerability is exploited. Additionally, deploying web application firewalls and implementing security headers can provide additional layers of protection against such attacks. Regular security audits and code reviews should be conducted to identify similar path traversal vulnerabilities in other applications and systems. The vulnerability demonstrates the critical importance of proper input validation and the principle of least privilege in web application security, as it shows how a single flaw in path handling can provide extensive access to system resources and potentially lead to more severe compromises. Organizations should also consider implementing automated security testing tools that can detect directory traversal vulnerabilities during the development lifecycle and regular security assessments to prevent exploitation of similar issues.