CVE-2018-0764 in .NET Framework
Summary
by MITRE
Microsoft .NET Framework 1.1, 2.0, 3.0, 3.5, 3.5.1, 4, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2 and 5.7 and .NET Core 1.0. 1.1 and 2.0 allow a denial of service vulnerability due to the way XML documents are processed, aka ".NET and .NET Core Denial Of Service Vulnerability". This CVE is unique from CVE-2018-0765.
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Analysis
by VulDB Data Team • 01/20/2023
This vulnerability affects multiple versions of Microsoft .NET Framework and .NET Core implementations, specifically targeting the XML processing mechanisms within these frameworks. The flaw manifests as a denial of service condition that occurs when the systems process malformed XML documents, creating a potential vector for attackers to disrupt services and applications relying on these frameworks. The vulnerability is particularly concerning because it spans across numerous framework versions, indicating a fundamental issue in the XML handling code that has persisted through multiple releases and iterations.
The technical root cause of this vulnerability lies in the insufficient validation and handling of XML document structures within the .NET processing pipeline. When the framework encounters specially crafted XML content, the parsing mechanisms can enter infinite loops or consume excessive system resources, leading to application crashes or unresponsiveness. This behavior is classified as a resource exhaustion vulnerability where the XML parser fails to properly validate document boundaries and recursive structures, allowing malicious input to cause the system to consume all available memory or processing power. The vulnerability falls under CWE-400 which specifically addresses unchecked resource consumption, making it particularly dangerous in production environments where these frameworks handle high volumes of incoming data.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire application availability and system stability. Applications built on affected .NET versions that process untrusted XML input become vulnerable to attacks that can bring down services, particularly in web applications, database systems, and enterprise software that rely heavily on XML data exchange. Attackers can exploit this vulnerability by submitting carefully constructed XML documents that trigger the problematic parsing code paths, causing applications to become unresponsive or crash entirely. This type of attack can be particularly devastating in cloud environments or high-availability systems where service uptime is critical, as it can be used to perform distributed denial of service attacks against multiple targets simultaneously.
Mitigation strategies for this vulnerability include applying the relevant Microsoft security updates and patches that address the XML parsing issues in affected framework versions. Organizations should prioritize patch management processes to ensure all systems running affected .NET Framework or .NET Core implementations receive timely updates. Additionally, implementing input validation measures that sanitize XML data before processing can provide defense-in-depth protection against exploitation attempts. The use of XML parsers with stricter validation settings and limiting XML document complexity can help reduce the attack surface. From an operational security perspective, implementing monitoring and alerting systems that detect unusual resource consumption patterns can help identify exploitation attempts before they cause significant service disruption. This vulnerability also aligns with ATT&CK technique T1499 which covers network denial of service attacks, emphasizing the need for proper input validation and resource management controls in application security architectures.