CVE-2017-12677 in IdentityServer3
Summary
by MITRE
IdentityServer3 2.4.x, 2.5.x, and 2.6.x before 2.6.1 has XSS in an Angular expression on the authorize response page, which might allow remote attackers to obtain sensitive information about the IdentityServer authorization response.
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Analysis
by VulDB Data Team • 12/15/2022
The vulnerability identified as CVE-2017-12677 affects IdentityServer3 versions 2.4.x through 2.6.x prior to 2.6.1, representing a cross-site scripting flaw that specifically targets the authorization response page. This issue occurs within the Angular expression context of the web application's user interface, creating a potential attack vector that could be exploited by remote adversaries. The vulnerability stems from insufficient input validation and sanitization mechanisms within the authorization response handling process, where user-supplied data is directly rendered without proper escaping or encoding.
The technical implementation of this vulnerability involves the improper handling of Angular expressions within the authorize response page, which allows malicious actors to inject crafted payloads that execute within the context of the victim's browser. This flaw specifically impacts the authorization response page where IdentityServer3 renders information about the authentication process, creating an environment where attacker-controlled data can be interpreted as executable JavaScript code. The vulnerability is classified under CWE-79, which represents Cross-Site Scripting, and aligns with ATT&CK technique T1203, which involves exploiting web application vulnerabilities to gain unauthorized access to sensitive information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it could potentially enable attackers to harvest session tokens, user credentials, or other sensitive authorization data. When an authenticated user visits a maliciously crafted authorization response page, the injected JavaScript code executes in their browser context, potentially allowing attackers to steal cookies, modify page content, or redirect users to malicious sites. This creates a significant risk for organizations relying on IdentityServer3 for authentication services, as successful exploitation could compromise the entire authentication flow and potentially lead to unauthorized system access. The vulnerability affects the core authentication mechanisms of the platform, undermining the security assurances that IdentityServer3 is designed to provide.
Organizations should implement immediate mitigations including upgrading to IdentityServer3 version 2.6.1 or later, which contains the necessary patches to address the XSS vulnerability. Additional protective measures include implementing proper input validation and output encoding for all user-supplied data within the authorization response handling, deploying content security policies to restrict script execution, and conducting thorough security reviews of all Angular expressions and dynamic content rendering processes. Security teams should also consider implementing web application firewalls to detect and block suspicious requests targeting the authorization endpoints, while monitoring for unusual patterns in authentication response handling that might indicate exploitation attempts. The remediation process should include comprehensive testing to ensure that the patched version properly handles all edge cases in authorization response generation without introducing regressions in functionality.