CVE-2006-2405 in Unclassified NewsBoard
Summary
by MITRE
Directory traversal vulnerability in unb_lib/abbc.conf.php in Unclassified NewsBoard (UNB) 1.6.1 patch 1 and earlier, when register_globals is enabled, allows remote attackers to include arbitrary files via .. (dot dot) sequences and a trailing null byte (%00) in the ABBC[Config][smileset] parameter to unb_lib/abbc.css.php.
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Analysis
by VulDB Data Team • 07/12/2021
The vulnerability identified as CVE-2006-2405 represents a critical directory traversal flaw within the Unclassified NewsBoard (UNB) content management system version 1.6.1 patch 1 and earlier. This weakness specifically resides in the file unb_lib/abbc.conf.php and manifests when the PHP configuration parameter register_globals is enabled on the web server. The vulnerability exploits a fundamental flaw in input validation and file inclusion mechanisms, creating a pathway for remote attackers to access arbitrary files on the target system. The attack vector leverages the ABBC[Config][smileset] parameter within the unb_lib/abbc.css.php script, utilizing directory traversal sequences combined with a trailing null byte to bypass security restrictions.
The technical exploitation of this vulnerability occurs through the manipulation of the smileset parameter which is processed without adequate sanitization or validation. When register_globals is enabled, PHP automatically creates global variables from GET, POST, and cookie data, significantly increasing the attack surface. Attackers can construct malicious URLs that include .. (dot dot) sequences to navigate up directory trees and append a null byte (%00) to terminate strings prematurely. This combination allows the attacker to specify file paths that extend beyond the intended directory boundaries, potentially accessing sensitive files such as configuration files, database credentials, or other system resources that should remain protected from unauthorized access. The vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it provides attackers with the capability to execute arbitrary code on the affected system. Since the vulnerability allows for arbitrary file inclusion, attackers can potentially upload malicious files and execute them as PHP scripts, leading to complete system compromise. The risk is particularly severe in environments where register_globals remains enabled, as this configuration is inherently insecure and was deprecated in later PHP versions due to its dangerous implications. Additionally, the vulnerability can be exploited to gain unauthorized access to user data, modify content, or establish persistent backdoors within the web application. This weakness significantly undermines the security posture of any system running vulnerable versions of UNB, as it provides a straightforward method for attackers to bypass authentication mechanisms and escalate privileges.
Mitigation strategies for CVE-2006-2405 require immediate action to address both the immediate vulnerability and underlying security misconfigurations. The primary recommendation involves upgrading to a patched version of Unclassified NewsBoard, as version 1.6.1 patch 2 and later versions contain proper input validation and sanitization mechanisms. Organizations should also disable register_globals in their PHP configuration files, as this setting fundamentally undermines web application security by creating dangerous global variables from user input. Additional protective measures include implementing proper input validation and sanitization routines, restricting file inclusion paths through the use of allow_url_include and allow_url_fopen directives set to off, and deploying web application firewalls that can detect and block malicious directory traversal attempts. The vulnerability demonstrates the importance of following secure coding practices and adhering to the principle of least privilege when designing web applications. Security professionals should also consider implementing automated scanning tools to identify similar vulnerabilities across their application portfolio, as directory traversal flaws remain common in legacy web applications. This vulnerability serves as a reminder of the critical importance of keeping software updated and maintaining secure configuration practices to prevent attackers from exploiting known weaknesses in web applications.