CVE-2013-3922 in FTP Drive + HTTP Server
Summary
by MITRE
Directory traversal vulnerability in Gummy Bear Studios FTP Drive + HTTP Server 1.0.4 and earlier allows remote attackers to read arbitrary files via a ..%2f (encoded dot dot slash) in a GET request.
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Analysis
by VulDB Data Team • 02/23/2018
The vulnerability identified as CVE-2013-3922 represents a critical directory traversal flaw within the Gummy Bear Studios FTP Drive + HTTP Server version 1.0.4 and earlier implementations. This weakness arises from insufficient input validation and improper handling of file path references in HTTP requests, creating an avenue for malicious actors to access sensitive system files that should remain protected. The vulnerability specifically manifests when the server fails to properly sanitize or normalize file paths submitted through GET requests, allowing attackers to manipulate directory navigation sequences through encoded characters.
The technical exploitation of this vulnerability relies on the manipulation of URL-encoded sequences where double dots followed by forward slashes are encoded as ..%2f. This encoding bypasses basic security checks that might otherwise recognize standard directory traversal attempts such as ../ or ..\, enabling attackers to navigate beyond the intended directory boundaries. When the HTTP server processes these malformed requests, it fails to properly validate the path components, allowing the system to interpret the encoded traversal sequences as legitimate navigation commands. This flaw directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities.
The operational impact of this vulnerability extends far beyond simple information disclosure, as remote attackers can potentially access sensitive files including configuration data, user credentials, application source code, and system binaries. The remote nature of the attack means that exploitation does not require physical access to the target system, making it particularly dangerous for networked environments where the FTP server may be exposed to untrusted networks. Attackers can leverage this vulnerability to gain unauthorized access to critical system resources, potentially leading to complete system compromise through subsequent exploitation of other vulnerabilities or by using stolen credentials for lateral movement within the network.
Security professionals should recognize this vulnerability as part of the broader ATT&CK framework's privilege escalation and credential access techniques, where initial reconnaissance and information gathering lead to more sophisticated attacks. The vulnerability's classification as a remote code execution vector through file access demonstrates how seemingly simple input validation failures can create pathways for comprehensive system compromise. Organizations should implement immediate mitigations including input validation, path normalization, and access control enforcement to prevent exploitation of this weakness. The recommended defensive measures include deploying web application firewalls, implementing proper file access controls, and ensuring that all server components are updated to versions that properly handle path traversal attempts through both encoded and unencoded sequences.