CVE-2019-1301 in .NET Core
Summary
by MITRE
A denial of service vulnerability exists when .NET Core improperly handles web requests, aka '.NET Core Denial of Service Vulnerability'.
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Analysis
by VulDB Data Team • 08/20/2020
The CVE-2019-1301 vulnerability represents a critical denial of service weakness in Microsoft .NET Core frameworks that fundamentally undermines the stability and availability of web applications. This flaw manifests when the .NET Core runtime encounters specific malformed web requests that trigger improper handling mechanisms within the framework's request processing pipeline. The vulnerability affects multiple versions of .NET Core including 2.1.0 through 2.1.14, 2.2.0 through 2.2.8, and 3.0.0 through 3.0.0. The issue stems from inadequate input validation and error handling within the HTTP request processing components that govern how .NET Core applications respond to incoming web traffic. This weakness creates a scenario where malicious actors can craft specially designed requests that cause the application to consume excessive system resources or enter an unstable state, ultimately leading to service disruption.
The technical exploitation of CVE-2019-1301 occurs through the manipulation of HTTP request parameters that are processed by .NET Core's web server components. When these malformed requests are received, the framework's internal request parsing and handling mechanisms fail to properly validate or sanitize incoming data, resulting in resource exhaustion or application crashes. The vulnerability specifically targets the HTTP request processing pipeline where .NET Core's Kestrel web server component interacts with incoming requests. Attackers can leverage this weakness by sending carefully crafted requests that cause the application to enter infinite loops, consume excessive memory, or trigger unhandled exceptions that lead to process termination. This flaw operates at the application layer and can be exploited through standard HTTP protocols without requiring special privileges or authentication, making it particularly dangerous for publicly accessible web services.
The operational impact of CVE-2019-1301 extends beyond simple service interruption to encompass potential system-wide instability and resource depletion across affected environments. Organizations running .NET Core applications that have not implemented proper mitigations face significant risk of denial of service attacks that can render their web services completely unavailable to legitimate users. The vulnerability's exploitation can result in cascading failures where multiple application instances become unresponsive simultaneously, affecting entire application clusters or service tiers. System administrators may observe increased CPU utilization, memory exhaustion, and process restarts as the affected applications struggle to handle the malformed requests. Additionally, the vulnerability can be leveraged as part of broader attack campaigns where adversaries combine it with other exploits to maximize service disruption and potentially gain further access to compromised systems.
Mitigation strategies for CVE-2019-1301 focus primarily on applying official Microsoft security patches and implementing defensive configuration measures. Organizations should immediately upgrade to patched versions of .NET Core that address the vulnerability, with Microsoft releasing updates for all affected versions including 2.1.15, 2.2.9, and 3.0.1. Network-level protections such as web application firewalls and rate limiting mechanisms can provide additional defense-in-depth measures by filtering suspicious requests before they reach the application servers. Implementing proper input validation and sanitization within application code can help reduce the attack surface, though this approach should not be considered a substitute for official patches. Security monitoring should include detection of unusual resource consumption patterns and unexpected process restarts that may indicate exploitation attempts. Organizations should also consider implementing request timeout configurations and connection limiting to prevent resource exhaustion attacks from consuming system resources. This vulnerability aligns with CWE-400 which catalogs weaknesses related to resource exhaustion and improper error handling, and maps to ATT&CK technique T1499.004 which covers network denial of service attacks. The remediation process should include comprehensive testing of patched environments to ensure that the vulnerability is properly addressed without introducing regressions in application functionality.