CVE-2019-16282 in Express Invoice
Summary
by MITRE
In NCH Express Invoice v7.12, persistent cross site scripting (XSS) exists via the Invoices/Items/Customers/Quotes input field. An authenticated unprivileged user can add/modify the Invoices/Items/Customers fields parameter to inject arbitrary JavaScript.
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Analysis
by VulDB Data Team • 10/15/2019
The vulnerability identified as CVE-2019-16282 represents a critical persistent cross site scripting flaw within NCH Express Invoice version 7.12 that poses significant security risks to organizations relying on this invoicing software. This vulnerability specifically affects the Invoices/Items/Customers/Quotes input fields, creating an attack vector where authenticated but unprivileged users can manipulate the application's data handling mechanisms to inject malicious JavaScript code. The flaw stems from inadequate input validation and output encoding practices within the web application's user interface components, allowing attackers to persistently execute malicious scripts in the context of other users' browsers.
The technical implementation of this vulnerability demonstrates a classic persistent XSS attack pattern where user-supplied data flows directly into the application's output without proper sanitization or encoding. When an authenticated user modifies fields related to invoices, items, customers, or quotes, the application fails to adequately validate or escape the input before storing and subsequently rendering it. This creates a persistent storage vector where malicious JavaScript code becomes permanently embedded within the application's database or storage mechanisms. The vulnerability is particularly concerning because it requires only authentication to the application, meaning that any user with valid login credentials can exploit this weakness regardless of their privilege level, making it a significant concern for internal threat scenarios.
From an operational impact perspective, this vulnerability enables attackers to execute arbitrary JavaScript code in the context of other users' browsers, potentially leading to session hijacking, credential theft, data exfiltration, and privilege escalation within the application environment. The persistent nature of the vulnerability means that once malicious code is injected, it will execute every time affected pages are loaded, creating a long-term attack surface. Attackers could leverage this capability to steal session cookies, redirect users to malicious websites, modify application data, or even escalate their privileges within the system. The vulnerability affects the core business functionality of the invoicing application, potentially compromising financial data integrity and customer information security.
The flaw aligns with CWE-79 which specifically addresses cross-site scripting vulnerabilities, and follows patterns commonly referenced in the ATT&CK framework under techniques such as T1059.007 for command and scripting interpreter and T1566 for credential access through social engineering. Organizations should implement comprehensive input validation mechanisms, including strict sanitization of user inputs and proper output encoding before rendering data in web contexts. The recommended mitigations include implementing Content Security Policy headers, employing proper input validation libraries, conducting regular security testing, and ensuring that all user inputs are properly escaped before being stored or displayed. Additionally, organizations should consider implementing role-based access controls to limit the impact of potential exploitation and maintain regular patch management processes to address known vulnerabilities in third-party software components.