CVE-2018-8292 in .NET Core
Summary
by MITRE
An information disclosure vulnerability exists in .NET Core when authentication information is inadvertently exposed in a redirect, aka ".NET Core Information Disclosure Vulnerability." This affects .NET Core 2.1, .NET Core 1.0, .NET Core 1.1, PowerShell Core 6.0.
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Analysis
by VulDB Data Team • 05/25/2023
The CVE-2018-8292 vulnerability represents a critical information disclosure flaw within Microsoft's .NET Core framework that emerged from improper handling of authentication data during web application redirects. This vulnerability specifically impacts versions 1.0, 1.1, and 2.1 of .NET Core alongside PowerShell Core 6.0, creating a significant security risk for applications that rely on authentication mechanisms and redirect functionalities. The flaw stems from the framework's inability to properly sanitize authentication tokens and credentials when redirecting users between different endpoints or applications, potentially exposing sensitive information to unauthorized parties. The vulnerability falls under the broader category of information disclosure weaknesses that can be categorized under CWE-200, which addresses the exposure of sensitive information to an unauthorized actor. This issue aligns with ATT&CK technique T1566.001, which involves credential access through phishing or social engineering, as the vulnerability enables attackers to obtain authentication information through redirect mechanisms rather than traditional attack vectors.
The technical implementation of this vulnerability occurs when .NET Core applications handle authentication flows that involve redirects to external or internal endpoints. During these redirect operations, the framework fails to properly strip or encode authentication parameters that may be present in the redirect URL, leading to the inadvertent exposure of sensitive data such as authentication tokens, session identifiers, or other credential-related information. This occurs particularly when applications utilize the standard redirect mechanisms provided by the framework without implementing additional security measures to sanitize the redirect URLs. The flaw is exacerbated by the fact that authentication information is often passed as query parameters or in the URL itself during redirect operations, making it susceptible to interception by malicious actors who may be monitoring network traffic or have access to server logs. The vulnerability becomes more pronounced in scenarios where applications are configured to redirect users to external domains or when applications implement complex authentication flows that involve multiple redirect hops.
The operational impact of CVE-2018-8292 extends beyond simple information disclosure, potentially enabling attackers to escalate privileges, conduct session hijacking, or perform further exploitation attempts. When authentication information is exposed through redirect mechanisms, attackers can leverage this data to impersonate legitimate users, gain unauthorized access to protected resources, or establish persistent access to sensitive systems. The vulnerability is particularly dangerous in environments where applications handle sensitive data or where authentication tokens are long-lived, as the exposure of even a single token can provide extended access to compromised systems. Organizations using affected .NET Core versions face significant risk of credential compromise, especially in scenarios where applications redirect to third-party services or where redirect URLs contain sensitive information. The vulnerability can be exploited through various attack vectors including man-in-the-middle attacks, server log monitoring, or through network traffic analysis, making it difficult to detect and mitigate without proper application-level controls.
Mitigation strategies for CVE-2018-8292 require immediate implementation of security patches provided by Microsoft, along with comprehensive application-level modifications to prevent exposure of authentication information during redirect operations. Organizations should prioritize updating to patched versions of .NET Core and PowerShell Core where available, as Microsoft released security updates specifically addressing this vulnerability. Application developers must implement proper URL sanitization techniques to ensure that authentication parameters are not included in redirect URLs, particularly when redirecting to external domains. The implementation of secure redirect practices should include validation of redirect targets, use of temporary tokens instead of long-lived credentials in URLs, and proper encoding of all redirect parameters. Additional mitigations involve implementing network-level protections such as web application firewalls that can detect and block suspicious redirect patterns, along with monitoring and logging mechanisms to identify potential exploitation attempts. Security teams should also conduct thorough code reviews to identify all redirect operations within affected applications and ensure that proper security controls are implemented. The vulnerability underscores the importance of following secure coding practices and the principle of least privilege in redirect implementations, as recommended by OWASP and other security standards. Organizations should also consider implementing additional authentication layers such as multi-factor authentication to reduce the impact of potential credential exposure, as this vulnerability can significantly weaken overall security posture when exploited.