CVE-2007-1623 in realGuestbook
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in realGuestbook 5.01, when register_globals is enabled, allow remote attackers to inject arbitrary web script or HTML via the (1) bg_color_1, (2) fs_menu, (3) fc_menu, (4) ff_menu, (5) bg_color_2, (6) fs_normal, (7) fc_normal, and (8) ff_normal parameters to welcome_admin.php; and possibly unspecified other parameters and files. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 09/01/2017
The CVE-2007-1623 vulnerability represents a critical cross-site scripting flaw in the realGuestbook 5.01 web application that specifically exploits the dangerous combination of insecure input handling and the deprecated register_globals PHP configuration setting. This vulnerability classifies under CWE-79 as a failure to sanitize user input, creating a pathway for malicious actors to inject arbitrary web scripts into web applications. The flaw manifests when the register_globals directive is enabled in the PHP configuration, which automatically converts HTTP request variables into global variables, effectively bypassing normal input validation mechanisms. The vulnerability affects the welcome_admin.php administrative interface and targets eight specific parameters including bg_color_1, fs_menu, fc_menu, ff_menu, bg_color_2, fs_normal, fc_normal, and ff_normal, which control various visual elements of the guestbook's administrative interface. These parameters are processed without proper sanitization or output encoding, allowing attackers to inject malicious payloads that execute in the context of other users' browsers.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform a wide range of malicious activities through the compromised administrative interface. When an attacker successfully exploits these XSS vulnerabilities, they can execute scripts in the context of authenticated administrators, potentially leading to complete system compromise. The attack vector leverages the insecure handling of user-supplied parameters that are directly incorporated into HTML output without proper encoding or validation. This creates opportunities for session hijacking, credential theft, and privilege escalation attacks that align with ATT&CK technique T1566 for initial access through malicious web content. The vulnerability's exploitation becomes particularly dangerous because it targets administrative functions, meaning successful attacks could result in unauthorized modifications to guestbook content, data exfiltration, or even complete administrative control over the application.
Mitigation strategies for CVE-2007-1623 must address both the immediate vulnerability and underlying architectural issues that make such attacks possible. The most effective immediate solution involves disabling the register_globals PHP directive in the php.ini configuration file, as this setting fundamentally undermines input validation security measures. Additionally, implementing proper output encoding for all user-supplied data before rendering it in HTML contexts prevents XSS exploitation regardless of configuration settings. The application should employ strict input validation that filters out potentially malicious characters and implements Content Security Policy headers to further mitigate script execution risks. Security practitioners should also consider implementing web application firewalls to detect and block suspicious parameter values, and establish regular security audits to identify similar input handling vulnerabilities. The vulnerability demonstrates the critical importance of following secure coding practices and adhering to the principle of least privilege, as the exploitation of such flaws can lead to complete system compromise through the administrative interface. Organizations should also ensure that legacy applications like realGuestbook 5.01 are properly maintained or migrated to modern secure frameworks that implement proper input validation and output encoding by default.