CVE-2023-3559 in PHP GZ Appointment Scheduling Script
Summary
by MITRE • 07/10/2023
A vulnerability classified as problematic was found in GZ Scripts PHP GZ Appointment Scheduling Script 1.8. Affected by this vulnerability is an unknown functionality of the file /load.php. The manipulation of the argument first_name/second_name/phone/address_1/country leads to cross site scripting. The attack can be launched remotely. The identifier VDB-233353 was assigned to this vulnerability. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 07/25/2023
This cross site scripting vulnerability exists in the GZ Appointment Scheduling Script version 1.8, specifically within the /load.php file where user input parameters including first_name, second_name, phone, address_1, and country are processed without adequate sanitization. The vulnerability falls under the CWE-79 category of Cross Site Scripting, which represents one of the most prevalent and dangerous web application security flaws. The attack vector is remotely exploitable, meaning malicious actors can inject malicious scripts through web browsers without requiring physical access to the system. The lack of vendor response to early disclosure attempts creates a significant security gap where organizations using this script remain exposed to potential exploitation.
The technical implementation of this vulnerability stems from the script's failure to properly validate and sanitize user-supplied input before processing or displaying it within web pages. When users submit appointment information through the scheduling interface, the parameters first_name, second_name, phone, address_1, and country are directly incorporated into the application's output without proper HTML encoding or input validation mechanisms. This allows attackers to inject malicious JavaScript code that executes in the context of other users' browsers. The vulnerability operates at the application layer and can be categorized under ATT&CK technique T1566.001 for spearphishing with malicious attachments or links, as it enables the delivery of malicious scripts through legitimate application interfaces.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable session hijacking, credential theft, and data exfiltration from authenticated users. Attackers could potentially leverage this flaw to steal session cookies, redirect users to malicious sites, or inject additional malicious content that could compromise the entire application. The remote exploitation capability means that threat actors can target users from anywhere on the internet without requiring local network access. Organizations running this script are particularly vulnerable as the attack requires no specialized tools beyond standard web browser capabilities, making it accessible to a broad range of threat actors. The vulnerability represents a critical security gap in web application defenses, especially considering the sensitive nature of appointment scheduling data that may contain personal information and potentially financial details.
Mitigation strategies should include immediate implementation of input validation and output encoding mechanisms to prevent malicious script injection, followed by application of available vendor patches or updates. Organizations should implement proper HTML escaping for all user-supplied data before rendering it in web pages, and consider implementing content security policies to further limit script execution capabilities. The absence of vendor response necessitates proactive security measures including regular security audits, penetration testing, and monitoring for suspicious activity. Additionally, network segmentation and web application firewalls can provide additional layers of protection. The vulnerability demonstrates the critical importance of maintaining current security practices and vendor communication, as the lack of vendor response creates an extended window of exposure for affected organizations.