CVE-2020-17055: Windows 10 Privilege Escalation Vulnerability

CVE-2020-17055 Overview

CVE-2020-17055 is a Windows Remote Access Elevation of Privilege vulnerability affecting multiple versions of Microsoft Windows operating systems. This vulnerability allows an attacker with local access to elevate their privileges on the affected system through the Windows Remote Access component.

Critical Impact

Successful exploitation enables an attacker to gain elevated privileges on the system, potentially allowing them to install programs, view, change, or delete data, or create new accounts with full user rights.

Affected Products

• Microsoft Windows 10 (multiple versions including 1607, 1709, 1803, 1809, 1903, 1909, 2004, 20H2)
• Microsoft Windows 8.1
• Microsoft Windows RT 8.1
• Microsoft Windows Server 2008 SP2
• Microsoft Windows Server 2012 R2
• Microsoft Windows Server 2016 (multiple versions including 1903, 1909, 2004, 20H2)
• Microsoft Windows Server 2019

Discovery Timeline

• November 11, 2020 - CVE-2020-17055 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-17055

Vulnerability Analysis

This elevation of privilege vulnerability exists in the Windows Remote Access component across multiple Windows versions. The vulnerability requires local access and user interaction, meaning an attacker must either have physical access to the system or have already gained initial access through other means before they can exploit this flaw.

The attack complexity is low, indicating that once an attacker has the necessary access and can induce user interaction, exploitation is straightforward. Successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected system, allowing the attacker to operate with elevated privileges.

Root Cause

The vulnerability stems from improper handling within the Windows Remote Access subsystem. While Microsoft has not disclosed specific technical details about the root cause (classified as NVD-CWE-noinfo), the elevation of privilege nature suggests inadequate privilege checks or improper access control mechanisms within the Remote Access component that can be leveraged by an attacker to bypass security boundaries.

Attack Vector

The attack vector is local, requiring the attacker to have an existing presence on the target system. The exploitation scenario involves:

1. The attacker gains initial local access to a vulnerable Windows system
2. The attacker crafts a malicious request or input targeting the Windows Remote Access component
3. User interaction is required to trigger the vulnerability
4. Upon successful exploitation, the attacker's privileges are elevated, potentially to SYSTEM level

Since no verified proof-of-concept code is publicly available, the exploitation mechanism involves manipulating the Windows Remote Access component through local interfaces. Organizations should refer to the Microsoft Security Advisory for detailed technical guidance.

Detection Methods for CVE-2020-17055

Indicators of Compromise

• Unusual privilege escalation events in Windows Security Event logs (Event IDs 4672, 4673, 4674)
• Unexpected process creation from Remote Access related services with elevated privileges
• Anomalous registry modifications related to Remote Access configurations
• Suspicious DLL loading patterns in Remote Access component processes

Detection Strategies

• Monitor Windows Security logs for privilege escalation attempts and unusual token elevation events
• Implement endpoint detection rules to identify suspicious activity within Remote Access service contexts
• Deploy behavioral analysis to detect anomalous process hierarchies where low-privilege processes spawn high-privilege children
• Utilize SentinelOne's behavioral AI engine to detect privilege escalation patterns in real-time

Monitoring Recommendations

• Enable verbose logging for Windows Remote Access services and related components
• Configure SIEM alerts for privilege escalation indicators correlated with Remote Access activity
• Implement file integrity monitoring on critical Remote Access system files
• Regularly audit user privileges and service account permissions

How to Mitigate CVE-2020-17055

Immediate Actions Required

• Apply the Microsoft security update released in November 2020 immediately on all affected systems
• Prioritize patching of internet-facing and critical infrastructure systems
• Review and restrict local access privileges to minimize attack surface
• Implement application whitelisting to prevent unauthorized code execution

Patch Information

Microsoft has released security updates to address this vulnerability as part of their November 2020 Patch Tuesday release. Detailed patch information and download links are available in the Microsoft Security Advisory for CVE-2020-17055. Organizations should apply the appropriate update for their specific Windows version and architecture.

Workarounds

• Restrict local access to systems by implementing strong access controls and the principle of least privilege
• Disable or restrict Windows Remote Access services where not required for business operations
• Implement network segmentation to limit lateral movement if a system is compromised
• Deploy endpoint protection solutions with behavioral detection capabilities to identify exploitation attempts

# Verify Windows Remote Access service status
sc query "RasMan"
sc query "RemoteAccess"

# If not required, disable Remote Access services
sc config "RasMan" start= disabled
sc config "RemoteAccess" start= disabled

# Check for installed security updates (PowerShell)
Get-HotFix | Where-Object {$_.InstalledOn -gt "2020-11-01"} | Format-Table