CVE-2020-7741 in hellojs Package
Summary
by MITRE • 10/06/2020
This affects the package hellojs before 1.18.6. The code get the param oauth_redirect from url and pass it to location.assign without any check and sanitisation. So we can simply pass some XSS payloads into the url param oauth_redirect, such as javascript:alert(1).
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Analysis
by VulDB Data Team • 11/16/2020
The vulnerability identified as CVE-2020-7741 affects the hellojs package version 1.18.5 and earlier, representing a critical cross-site scripting flaw that stems from improper input validation and sanitization practices. This security weakness exists within the authentication flow where the application processes the oauth_redirect parameter directly from URL parameters without implementing any form of validation or sanitization measures. The flaw allows attackers to inject malicious payloads through the redirect parameter, creating an avenue for executing arbitrary JavaScript code within the context of the victim's browser session.
The technical implementation of this vulnerability occurs when the application retrieves the oauth_redirect parameter from the URL and immediately passes it to the location.assign() method without any preprocessing. This direct parameter handling creates a classic cross-site scripting vector where attackers can craft malicious URLs containing javascript: protocol handlers or other XSS payloads. The vulnerability specifically aligns with CWE-79, which categorizes cross-site scripting flaws as weaknesses that allow attackers to inject client-side scripts into web applications. The absence of input sanitization creates an environment where untrusted data flows directly into the browser's execution context, bypassing standard security mechanisms.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, data theft, and privilege escalation attacks. When a victim clicks on a maliciously crafted link containing the XSS payload, the browser will execute the injected JavaScript code within the legitimate application context, potentially allowing attackers to steal session cookies, modify application behavior, or redirect users to malicious sites. This vulnerability particularly affects web applications that rely on hellojs for social authentication flows, where users may be directed to authenticate through third-party providers and then redirected back to the application. The attack surface is broadened because the vulnerability can be exploited through various vectors including phishing emails, compromised websites, or malicious advertisements that redirect users to the vulnerable application with crafted parameters.
Organizations and developers should implement immediate mitigations to address this vulnerability by upgrading to hellojs version 1.18.6 or later, which contains the necessary patches to properly validate and sanitize redirect parameters. The recommended approach includes implementing strict input validation that verifies redirect URLs against a predefined whitelist of trusted domains, implementing proper URL parsing and sanitization routines, and employing Content Security Policy headers to limit script execution capabilities. Additionally, organizations should conduct comprehensive security reviews of all authentication flows to identify similar input handling patterns that may present analogous vulnerabilities. The remediation process should also include monitoring for potential exploitation attempts and implementing proper logging mechanisms to detect suspicious redirect parameter usage. This vulnerability demonstrates the critical importance of input validation and the principle of least privilege in web application security, aligning with ATT&CK technique T1059.007 for script injection and T1566 for phishing attacks that leverage authentication flows.