CVE-2005-2008 in Webserver
Summary
by MITRE
Yaws Webserver 1.55 and earlier allows remote attackers to obtain the source code for yaws scripts via a request to a yaw script with a trailing %00 (null).
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Analysis
by VulDB Data Team • 06/02/2019
The vulnerability identified as CVE-2005-2008 affects the Yaws web server version 1.55 and earlier, presenting a critical security flaw that enables remote attackers to access sensitive source code files. This vulnerability stems from improper handling of null byte sequences in HTTP requests, specifically when requesting yaws scripts with trailing %00 characters. The Yaws web server, designed for serving dynamic content using the yaws scripting language, fails to adequately sanitize input parameters that contain null byte terminators, creating an exploitable condition that compromises the confidentiality of server-side script files.
The technical implementation of this vulnerability exploits a classic buffer overread or input validation weakness where the web server processes requests containing null byte sequences without proper sanitization. When an attacker submits a request to a yaws script with a trailing %00 character, the server's request parsing mechanism fails to properly handle the null termination, potentially causing the application to read beyond intended memory boundaries or to misinterpret the request structure. This flaw falls under CWE-129, Input Validation, and more specifically CWE-707, Improper Neutralization of Special Elements used in a Command, as the null byte injection disrupts normal request processing. The vulnerability demonstrates characteristics of CWE-119, Improper Restriction of Operations within a Single Facility, where the server fails to properly restrict how input data is processed within its memory space.
The operational impact of this vulnerability is severe as it allows attackers to obtain the source code of yaws scripts, potentially exposing sensitive business logic, database connection strings, authentication mechanisms, and other proprietary code elements. This information disclosure can enable attackers to conduct further attacks such as privilege escalation, data exfiltration, or exploitation of additional vulnerabilities within the application code. The vulnerability particularly affects web applications that rely on Yaws for dynamic content delivery and may be exploited in conjunction with other attack vectors to compromise entire web applications. The attack requires minimal sophistication and can be executed remotely, making it particularly dangerous for publicly accessible web servers. According to ATT&CK framework, this vulnerability maps to T1566.001, Phishing, and T1005, Data from Local System, as it enables unauthorized access to sensitive application data.
Mitigation strategies for CVE-2005-2008 should prioritize immediate patching of affected Yaws web server installations to version 1.56 or later, where the null byte handling has been properly addressed. System administrators should implement input validation measures that explicitly reject or sanitize null byte sequences in all HTTP request parameters before they reach the application layer. Network-level protections such as web application firewalls can be configured to detect and block requests containing null byte sequences, providing an additional layer of defense. Regular security audits should verify that no yaws scripts are accessible through unintended paths and that proper access controls are enforced. Organizations should also consider implementing monitoring solutions that can detect unusual patterns of script access or potential exploitation attempts. The vulnerability highlights the importance of proper input sanitization and the need for robust security testing of web server implementations, particularly in environments where dynamic scripting languages are used for web content delivery.