CVE-2018-3724 in general-file-server
Summary
by MITRE
general-file-server node module suffers from a Path Traversal vulnerability due to lack of validation of currpath, which allows a malicious user to read content of any file with known path.
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Analysis
by VulDB Data Team • 02/16/2020
The CVE-2018-3724 vulnerability resides within the general-file-server node module, a widely used component in web applications for serving static files. This particular weakness manifests as a path traversal flaw that stems from insufficient validation of the currpath parameter within the file serving logic. The vulnerability represents a critical security gap that directly enables unauthorized access to sensitive system files and directories. Attackers can exploit this issue by manipulating the path parameter to navigate beyond the intended directory boundaries and access files that should remain protected. The flaw operates by allowing malicious users to construct specific path sequences that bypass normal file access controls, effectively granting them read access to any file on the system where the vulnerable module is deployed.
The technical implementation of this vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This weakness enables attackers to access files and directories that are stored outside the intended directory structure by manipulating input parameters. The general-file-server module fails to properly sanitize or validate user-supplied path information, creating an opportunity for attackers to craft malicious requests that can traverse the file system hierarchy. The vulnerability specifically affects how the module processes the currpath parameter, which should normally be restricted to a predefined directory but instead accepts arbitrary path components that can be exploited to access system resources.
From an operational perspective, this vulnerability poses significant risks to organizations that rely on the general-file-server module for file serving capabilities. The impact extends beyond simple information disclosure, as attackers can potentially access configuration files, source code, database credentials, and other sensitive data stored on the same system. The attack vector is particularly concerning because it requires minimal privileges and can be executed through standard web requests, making it accessible to attackers with basic technical skills. Additionally, the vulnerability can be exploited to gain insights into the system architecture, potentially enabling more sophisticated attacks such as privilege escalation or further exploitation of other system weaknesses.
Mitigation strategies for CVE-2018-3724 should focus on implementing proper input validation and sanitization measures within the file serving module. Organizations should immediately upgrade to patched versions of the general-file-server module or implement custom validation logic that restricts file paths to predefined directories. The solution must include robust parameter validation that rejects any path components containing directory traversal sequences such as ../ or ..\, and implements proper path normalization to ensure that all file access operations remain within designated boundaries. Security teams should also consider implementing additional monitoring and logging mechanisms to detect unusual file access patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of input validation in web applications and aligns with ATT&CK technique T1083, which covers directory and file permissions discovery, as attackers can use path traversal to discover and access unauthorized files and directories within the system.