CVE-2017-5191 in Access Manager
Summary
by MITRE
An XSS vulnerability on the /NAGErrors URI in NetIQ Access Manager 4.2 and 4.3 exists because Access Gateway Error pages do not validate the HTTP Referer header.
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Analysis
by VulDB Data Team • 04/25/2017
The CVE-2017-5191 vulnerability represents a cross-site scripting flaw within NetIQ Access Manager versions 4.2 and 4.3 that specifically targets the /NAGErrors URI endpoint. This weakness stems from the Access Gateway's error handling mechanism failing to properly validate the HTTP Referer header, creating an exploitable condition that allows malicious actors to inject arbitrary script code into error pages displayed to users. The vulnerability resides in the application's security architecture where error responses are generated without adequate input sanitization or validation of the referer information, which is typically used to determine the origin of the request that triggered the error.
The technical implementation of this flaw occurs when the Access Gateway processes error conditions and generates error pages that incorporate user-supplied data from the HTTP Referer header without proper encoding or validation. When an attacker crafts a malicious request with a specially formatted referer value containing script code, the system processes this input directly into the error page output, creating a persistent XSS vector. This vulnerability operates under CWE-79 which classifies the weakness as "Cross-site Scripting" and aligns with ATT&CK technique T1059.008 for Scripting, specifically targeting the execution of malicious scripts through web application interfaces.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform session hijacking, credential theft, and data exfiltration from authenticated users. An attacker could craft malicious referer headers that redirect users to phishing pages, steal session cookies, or inject malicious content that persists across user sessions. The vulnerability affects organizations using NetIQ Access Manager as it provides an entry point for attackers to compromise user sessions and potentially escalate privileges within the access management infrastructure. This weakness particularly impacts environments where the access manager serves as a critical authentication gateway, making it a prime target for credential harvesting attacks.
Mitigation strategies for CVE-2017-5191 should focus on implementing proper input validation and output encoding for all user-supplied data, particularly headers like the HTTP Referer. Organizations should ensure that the Access Gateway error handling mechanism sanitizes all input parameters before incorporating them into error page content. The recommended approach involves implementing strict header validation that either filters out potentially malicious content or properly encodes all referer values before display. Additionally, deploying web application firewalls and implementing content security policies can provide additional layers of protection. The vulnerability demonstrates the importance of secure coding practices in web application development and the necessity of validating all external inputs regardless of their expected source. Organizations should also consider upgrading to patched versions of NetIQ Access Manager where available, as this vulnerability was addressed through proper input validation mechanisms in subsequent releases.