CVE-2020-1108 in .NET Core
Summary
by MITRE
A denial of service vulnerability exists when .NET Core or .NET Framework improperly handles web requests, aka '.NET Core & .NET Framework Denial of Service Vulnerability'.
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Analysis
by VulDB Data Team • 10/17/2020
This vulnerability represents a critical denial of service condition affecting Microsoft .NET Core and .NET Framework implementations that stems from improper handling of web requests within the HTTP processing pipeline. The flaw manifests when applications processing incoming web requests fail to properly validate or sanitize input parameters, leading to resource exhaustion or application instability. Attackers can exploit this weakness by crafting malicious HTTP requests that trigger specific code paths within the .NET runtime, causing the targeted application to consume excessive system resources or enter an unstable state. The vulnerability impacts both server-side applications and client applications that process web responses, making it particularly dangerous in enterprise environments where .NET applications form the backbone of numerous business-critical systems.
The technical implementation of this vulnerability involves the manipulation of HTTP request headers, query parameters, or request bodies in ways that cause the .NET framework to enter infinite loops or consume disproportionate memory resources. When the framework attempts to process these malformed requests, it triggers internal mechanisms that can lead to thread exhaustion, memory leaks, or stack overflow conditions. The flaw specifically affects the HTTP request parsing and routing components of the .NET runtime, where insufficient input validation allows attackers to craft requests that cause the application to continuously process the same request data or enter recursive processing states. This behavior aligns with CWE-400 vulnerability classification, which covers unrestricted resource consumption, and represents a classic example of a resource exhaustion attack vector.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire application availability and system stability. Organizations running .NET applications may experience complete service outages, increased system load, or degraded performance that affects multiple users simultaneously. The attack surface is particularly broad given the widespread adoption of .NET frameworks across enterprise applications, web services, and cloud deployments. Additionally, the vulnerability can be exploited through various attack vectors including direct HTTP requests, API calls, or even through proxy servers that forward requests to vulnerable applications. This makes it particularly dangerous in environments where applications are exposed to untrusted networks or user inputs, as the attack can be executed with minimal technical expertise.
Mitigation strategies for this vulnerability should focus on immediate patch application and implementation of defensive measures within the application architecture. Microsoft has released security updates that address the root cause by improving input validation and implementing better resource management within the HTTP processing pipeline. Organizations should prioritize applying these patches across all affected systems, particularly in production environments where the vulnerability could be exploited to cause significant business disruption. Network-level protections such as rate limiting, request filtering, and intrusion detection systems can provide additional defense-in-depth measures to detect and prevent exploitation attempts. The implementation of proper input validation, request size limits, and monitoring of resource consumption patterns can help identify and mitigate potential exploitation attempts before they cause service disruption. This vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing robust application security controls as outlined in the ATT&CK framework's defense evasion and privilege escalation categories.