CVE-2019-0793 in Windows
Summary
by MITRE
A remote code execution vulnerability exists when the Microsoft XML Core Services MSXML parser processes user input, aka 'MS XML Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-0790, CVE-2019-0791, CVE-2019-0792, CVE-2019-0795.
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Analysis
by VulDB Data Team • 07/11/2024
The vulnerability identified as CVE-2019-0793 represents a critical remote code execution flaw within Microsoft XML Core Services MSXML parser, specifically affecting versions of MSXML that process user input through the XML parsing engine. This vulnerability falls under the broader category of XML external entity processing issues that have plagued various software systems over the years. The flaw enables attackers to execute arbitrary code on vulnerable systems by leveraging malformed XML input that triggers unexpected behavior within the MSXML parsing component. The vulnerability is particularly concerning because it can be exploited remotely without requiring authentication, making it a prime target for automated attacks and widespread exploitation across networked environments. Microsoft categorizes this issue as a remote code execution vulnerability, indicating that successful exploitation could result in complete system compromise and unauthorized access to sensitive data and system resources.
The technical root cause of CVE-2019-0793 stems from improper input validation and processing within the MSXML parser's handling of XML documents, particularly when processing external entities or when encountering specific XML constructs that trigger buffer overflows or memory corruption conditions. This flaw manifests when the parser encounters specially crafted XML content that causes it to execute unintended code paths within the parsing engine. The vulnerability is classified as a buffer overflow or memory corruption issue that can be triggered through XML processing, which aligns with common CWE categories such as CWE-121 for buffer overflow conditions and CWE-125 for out-of-bounds read errors. The parser's handling of certain XML attributes or nested elements creates an opportunity for attackers to manipulate memory layout and execute malicious code with the privileges of the affected application or service.
From an operational perspective, the impact of CVE-2019-0793 extends far beyond simple exploitation, as it provides attackers with complete control over affected systems and can serve as a stepping stone for broader network infiltration. The vulnerability affects systems running various Microsoft products including Windows operating systems, Office applications, and web applications that utilize MSXML for processing XML data. Organizations using legacy systems or those that have not implemented proper security patches face significant risk from this vulnerability, as it can be leveraged for data exfiltration, privilege escalation, and persistent access to network resources. The attack surface is extensive since many web applications and services rely on XML processing for data exchange, making the exploitation potential particularly dangerous for enterprise environments where multiple systems may be vulnerable. Security professionals have noted that this vulnerability often goes undetected for extended periods due to the subtle nature of XML processing errors and the complexity of identifying malicious XML payloads in network traffic.
Mitigation strategies for CVE-2019-0793 require immediate implementation of Microsoft security patches and updates, as well as comprehensive network monitoring and input validation measures. Organizations should prioritize patch management processes to ensure all affected systems receive the relevant security updates from Microsoft, which typically address the underlying buffer overflow conditions in the MSXML parser. Network administrators should implement strict XML input validation at all system boundaries, particularly for web applications and services that process user-supplied XML data. The implementation of web application firewalls and XML security filters can help detect and prevent exploitation attempts by blocking malformed XML content before it reaches the vulnerable parser. Additionally, system hardening measures including disabling unnecessary XML processing capabilities, implementing least privilege access controls, and conducting regular vulnerability assessments can significantly reduce the risk of successful exploitation. This vulnerability aligns with ATT&CK tactics such as TA0002 for execution and TA0006 for credential access, as successful exploitation typically leads to system compromise and potential lateral movement within networks. Organizations should also consider implementing network segmentation and monitoring solutions that can detect unusual XML processing patterns or attempts to exploit the vulnerability through network traffic analysis and behavioral monitoring.