CVE-2017-17662 in Yawcam
Summary
by MITRE
Directory traversal in the HTTP server on Yawcam 0.2.6 through 0.6.0 devices allows attackers to read arbitrary files through a sequence of the form '.x./' or '....\x/' where x is a pattern composed of one or more (zero or more for the second pattern) of either \ or ..\ -- for example a '.\./', '....\/' or '...\./' sequence. For files with no extension, a single dot needs to be appended to ensure the HTTP server does not alter the request, e.g., a "GET /.\./.\./.\./.\./.\./.\./.\./windows/system32/drivers/etc/hosts." request.
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Analysis
by VulDB Data Team • 06/14/2024
The vulnerability CVE-2017-17662 represents a critical directory traversal flaw in the HTTP server component of Yawcam versions 0.2.6 through 0.6.0. This directory traversal vulnerability stems from insufficient input validation and sanitization within the web server's file access mechanisms, allowing attackers to bypass normal file access controls and retrieve arbitrary files from the underlying filesystem. The flaw specifically affects how the HTTP server processes directory navigation sequences, creating a pathway for unauthorized file access that could expose sensitive system information.
The technical implementation of this vulnerability exploits the way the HTTP server handles path traversal sequences such as '.x./' or '....\x/' where x represents patterns composed of backslashes or dot-dot sequences. Attackers can construct malicious requests using combinations like '.\./', '....\/', or '...\./' to navigate through the file system hierarchy and access files that should remain protected. The vulnerability becomes particularly potent when dealing with files that lack extensions, as demonstrated by the example of accessing '/windows/system32/drivers/etc/hosts.' where appending a single dot ensures the HTTP server does not modify the request. This behavior aligns with CWE-22 Directory Traversal vulnerability patterns, specifically targeting the improper neutralization of directory traversal characters in file paths.
The operational impact of this vulnerability is severe as it enables attackers to access critical system files including configuration data, authentication credentials, system logs, and potentially sensitive user information. The ability to traverse directories and access files such as the Windows hosts file demonstrates the potential for reconnaissance and privilege escalation attacks. This vulnerability directly maps to ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachments) as attackers can use this flaw to gather intelligence about the target system and potentially extract sensitive data. The vulnerability affects devices running Yawcam versions within the specified range, making it particularly concerning for users who have not updated their systems.
Mitigation strategies for this vulnerability include immediate patching and updating to the latest version of Yawcam that addresses the directory traversal flaw. System administrators should implement proper input validation and sanitization for all file access requests, ensuring that directory traversal sequences are properly detected and rejected. Network segmentation and access controls should be implemented to limit exposure of the affected HTTP server to unauthorized users. Additionally, monitoring for suspicious directory traversal patterns in web server logs can help detect exploitation attempts. The vulnerability highlights the importance of secure coding practices and input validation, particularly for web applications that handle file system access operations. Organizations should also consider implementing web application firewalls and intrusion detection systems to help prevent exploitation of similar directory traversal vulnerabilities in other applications and services.