CVE-2017-16101 in serverwg
Summary
by MITRE
serverwg is a simple http server. serverwg 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 • 02/15/2020
The vulnerability identified as CVE-2017-16101 affects serverwg, a straightforward http server implementation that suffers from a critical directory traversal flaw. This weakness allows remote attackers to access arbitrary files on the server's 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 http server's file access mechanisms.
The technical root cause of this vulnerability stems from inadequate sanitization of user-supplied input in the URL path processing logic. When serverwg receives requests containing directory traversal sequences, it fails to properly validate or sanitize these inputs before using them to construct file paths. This allows attackers to navigate outside the intended document root directory and access sensitive system files, configuration data, or other resources that should remain protected from external access. The flaw operates at the application layer and can be exploited through standard http requests without requiring authentication or special privileges.
From an operational perspective, this vulnerability presents a severe security risk as it enables attackers to potentially access confidential information, system configuration files, user data, or even execute arbitrary code if the server has sufficient privileges. The impact extends beyond simple information disclosure since attackers can leverage this access to escalate privileges, establish persistence, or use the retrieved information for further attacks. The vulnerability affects any system running serverwg where the http server process has access to sensitive filesystem locations, making it particularly dangerous in production environments.
Security professionals should implement immediate mitigations including input validation and sanitization of all URL parameters to prevent directory traversal sequences from being processed. The recommended approach involves implementing strict path validation that rejects any input containing "../" or similar traversal patterns. Additionally, deploying web application firewalls and implementing proper access controls can provide additional layers of protection. Organizations should also consider upgrading to patched versions of serverwg if available, and conducting comprehensive security audits of all http server implementations to identify similar vulnerabilities. This vulnerability aligns with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, and represents a common attack vector that maps to techniques described in the MITRE ATT&CK framework under the 'Initial Access' and 'Credential Access' phases.