CVE-2020-17035 in Windows
Summary
by MITRE • 11/11/2020
Windows Kernel Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 12/05/2020
This vulnerability represents a critical elevation of privilege flaw within the Windows kernel that allows attackers to escalate their privileges from a standard user account to system-level access. The vulnerability stems from improper validation of kernel-mode operations, specifically related to how the kernel handles certain memory management functions and privilege checks during system calls. Attackers can exploit this weakness by crafting malicious payloads that manipulate kernel data structures or bypass existing security mechanisms that should prevent unauthorized privilege escalation. The flaw exists in the kernel's handling of specific privilege validation routines, creating a path for malicious code execution with elevated privileges that can bypass standard security controls. This vulnerability directly impacts the core security model of Windows operating systems and represents a fundamental weakness in the kernel's privilege enforcement mechanisms.
The technical exploitation of CVE-2020-17035 occurs through manipulation of kernel memory structures and system call interfaces that should enforce strict privilege boundaries. Attackers typically leverage this vulnerability by first gaining a foothold on a target system through other attack vectors such as phishing or drive-by downloads, then using the kernel flaw to escalate their privileges to SYSTEM level access. The exploitation process involves crafting specific kernel-mode payloads that can manipulate the kernel's privilege checking mechanisms, often through stack-based buffer overflows or memory corruption techniques that allow attackers to modify kernel data structures. This type of vulnerability falls under the CWE-264 category of "Permissions, Privileges, and Access Controls" and specifically relates to CWE-787 "Out-of-bounds Write" and CWE-122 "Heap-based Buffer Overflow" when considering the memory corruption aspects of the exploit. The vulnerability demonstrates a classic kernel-mode privilege escalation pattern that has been documented in numerous security research publications and represents a well-known attack surface that security researchers have extensively studied.
The operational impact of this vulnerability is severe and far-reaching across enterprise environments, as successful exploitation can result in complete system compromise and persistent access to target networks. Once an attacker achieves SYSTEM-level privileges through this vulnerability, they can perform actions such as installing backdoors, modifying system files, accessing all user data, and establishing persistence mechanisms that are difficult to detect or remove. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern for organizations deploying these operating systems. Organizations that fail to patch this vulnerability face significant risk of advanced persistent threats and insider attacks that can leverage the elevated privileges to conduct long-term reconnaissance and data exfiltration activities. The exploitability of this vulnerability is enhanced by its potential for remote code execution, meaning attackers can potentially exploit it without requiring physical access to the target system, making it particularly dangerous for enterprise environments with remote work capabilities.
Mitigation strategies for CVE-2020-17035 primarily focus on immediate patch deployment and system hardening measures to reduce the attack surface. Microsoft released security update kb4580325 that addresses this vulnerability by correcting the kernel privilege validation routines and implementing additional checks to prevent the exploitation vectors. Organizations should prioritize immediate deployment of this security patch across all affected systems and implement network segmentation to limit potential lateral movement if exploitation occurs. Additional mitigations include disabling unnecessary services, implementing strict access controls, and monitoring for suspicious kernel-mode activity that could indicate exploitation attempts. Security teams should also consider implementing behavioral monitoring solutions that can detect anomalous privilege escalation patterns or kernel-mode memory corruption activities. The vulnerability aligns with ATT&CK technique T1068 "Exploitation for Privilege Escalation" and T1547.001 "Registry Run Keys / Startup Folder" as attackers often use privilege escalation to establish persistence mechanisms. Organizations should also conduct regular security assessments to identify systems that may not have received the patch and implement automated patch management solutions to ensure timely remediation of similar vulnerabilities. The incident response plan should include specific procedures for investigating potential exploitation attempts and containing the threat through network isolation and system reimaging when necessary.