CVE-2021-42841 in Insta HMS
Summary
by MITRE • 01/07/2022
Insta HMS before 12.4.10 is vulnerable to XSS because of improper validation of user-supplied input by multiple scripts. A remote attacker could exploit this vulnerability via a crafted URL to execute script in a victim's Web browser within the security context of the hosting Web site, once the URL is clicked. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials.
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Analysis
by VulDB Data Team • 01/09/2022
The vulnerability identified as CVE-2021-42841 affects Insta HMS versions prior to 12.4.10 and represents a critical cross-site scripting flaw that stems from inadequate input validation mechanisms within multiple scripts. This weakness creates a pathway for remote attackers to inject malicious scripts into web applications that process user-supplied data without proper sanitization. The vulnerability manifests when the application fails to adequately validate and escape user input before incorporating it into dynamic web content, allowing attackers to craft malicious URLs that can execute arbitrary JavaScript code within the context of a victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of URL parameters that are subsequently processed by the affected scripts. When a victim clicks on a crafted URL containing malicious input, the web application incorporates this unvalidated data into its response without proper HTML escaping or input sanitization. This creates a persistent XSS vector that operates within the security boundaries of the hosting website, enabling attackers to execute scripts in the victim's browser with the privileges and permissions of the legitimate user. The vulnerability specifically targets the input validation mechanisms in multiple scripts, suggesting a systemic weakness in the application's data handling processes rather than isolated code flaws.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to harvest sensitive authentication credentials through cookie-based session hijacking. When malicious scripts execute within a victim's browser, they can access and exfiltrate session cookies, authentication tokens, and other sensitive data stored in the browser's memory. This enables attackers to impersonate legitimate users and gain unauthorized access to protected resources, potentially leading to complete account compromise and further lateral movement within the target environment. The vulnerability's remote exploitability means that attackers can leverage it from anywhere on the internet without requiring physical access to the target system.
Organizations affected by this vulnerability should prioritize immediate remediation through the application of the vendor-provided patch or update to version 12.4.10 and subsequent releases. The mitigation strategy should include comprehensive input validation and output encoding across all user-facing scripts to prevent the injection of malicious content. Security measures should implement strict sanitization of all user-supplied input, including URL parameters, form fields, and any dynamic content generation processes. Additionally, organizations should deploy web application firewalls and implement content security policies to provide additional layers of protection against similar vulnerabilities. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a direct threat to the principle of least privilege and secure coding practices as outlined in various cybersecurity frameworks including those referenced in the ATT&CK framework's web application exploitation techniques. The vulnerability demonstrates the critical importance of input validation and output encoding as fundamental security controls in preventing client-side exploitation vectors.