CVE-2020-5362: Dell Chengming 3967 Auth Bypass Flaw

CVE-2020-5362 Overview

CVE-2020-5362 is an improper authorization vulnerability affecting Dell Client Consumer and Commercial platforms. The vulnerability exists in the Dell Manageability interface, where an unauthorized actor with local system access and OS administrator privileges can bypass the BIOS Administrator authentication mechanism to restore BIOS Setup configuration to default values.

This firmware-level security flaw represents a significant concern for enterprise environments where BIOS-level security controls are relied upon to enforce hardware security policies, prevent unauthorized boot device changes, and maintain system integrity configurations.

Critical Impact

Local attackers with OS administrator privileges can bypass BIOS Administrator authentication and reset BIOS settings to defaults, potentially disabling critical security features like Secure Boot, TPM settings, and boot device restrictions.

Affected Products

• Dell Latitude Series (3000, 5000, 7000, 9000 series laptops and 2-in-1 devices)
• Dell Optiplex Series (3000, 5000, 7000 series desktops and All-in-One systems)
• Dell Precision Workstations (3000, 5000, 7000 series mobile and tower workstations)
• Dell Inspiron Series (consumer laptops, desktops, and 2-in-1 devices)
• Dell Vostro Series (business laptops and desktops)
• Dell XPS Series (premium laptops and desktops)
• Dell G3, G5, G7 Gaming Series
• Dell Wyse Thin Clients (5070, 5470, 7040)
• Dell Embedded Box PC 5000
• Dell Chengming Series

Discovery Timeline

• June 10, 2020 - CVE-2020-5362 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-5362

Vulnerability Analysis

This vulnerability is classified under CWE-285 (Improper Authorization) and CWE-862 (Missing Authorization). The flaw exists within the Dell Manageability interface, a system management component that provides out-of-band and in-band management capabilities for Dell client systems.

The vulnerability allows an attacker who has already achieved OS-level administrator privileges to bypass the BIOS Administrator password protection. Under normal circumstances, BIOS Administrator authentication serves as an additional layer of defense-in-depth, preventing even OS administrators from modifying critical firmware settings without knowledge of the separate BIOS password.

The attack requires local access to the system, meaning remote exploitation is not possible without first compromising the target through other means. However, in scenarios involving insider threats, physical access, or post-compromise lateral movement, this vulnerability enables significant security policy circumvention.

Root Cause

The root cause stems from improper authorization checks in the Dell Manageability interface. The interface fails to properly validate that the requesting process has BIOS Administrator credentials before allowing BIOS configuration reset operations. This represents a missing authorization check that allows OS-level privileges to be escalated to BIOS-level control without proper authentication.

The Dell Manageability interface exposes functionality through the operating system that should require BIOS-level authentication. The authorization boundary between OS administrator privileges and BIOS administrator privileges is not properly enforced, creating an authentication bypass condition.

Attack Vector

The attack vector requires local system access with OS administrator privileges. An attacker would exploit this vulnerability through the following mechanism:

1. Attacker gains local access to a vulnerable Dell system with OS administrator privileges
2. Attacker interacts with the Dell Manageability interface through system management tools or APIs
3. The attacker issues commands to reset BIOS configuration without providing BIOS Administrator credentials
4. The system accepts the request due to missing authorization validation
5. BIOS settings are restored to factory defaults, potentially disabling Secure Boot, boot device restrictions, virtualization-based security settings, and other firmware-level protections

Once BIOS settings are reset, an attacker could reconfigure the system to boot from unauthorized devices, disable hardware security features, or prepare the system for further compromise such as bootkit installation.

Detection Methods for CVE-2020-5362

Indicators of Compromise

• Unexpected BIOS configuration changes detected during system boot or through management tools
• BIOS settings reverting to defaults without authorized administrator action
• Secure Boot or TPM configuration changes that were not initiated through proper change management
• Audit logs showing Dell Manageability interface access from unexpected processes or users

Detection Strategies

• Monitor Windows Event Logs for access to Dell system management interfaces and WMI providers
• Implement endpoint detection rules for processes interacting with Dell Manageability components
• Deploy file integrity monitoring on BIOS configuration storage locations where accessible
• Configure alerts for BIOS/UEFI configuration changes through enterprise management platforms like Microsoft SCCM or Dell OpenManage

Monitoring Recommendations

• Enable and centralize collection of firmware/BIOS change audit logs where available
• Implement behavioral analytics to detect unusual system management activity from compromised administrator accounts
• Monitor for persistence mechanisms that may follow BIOS security control bypass
• Utilize SentinelOne's endpoint protection to detect post-exploitation activity that may accompany BIOS tampering attempts

How to Mitigate CVE-2020-5362

Immediate Actions Required

• Apply BIOS firmware updates from Dell for all affected platforms as documented in the Dell Support Article
• Audit current BIOS configurations on deployed systems to establish baseline settings
• Restrict local administrator privileges following principle of least privilege
• Implement physical security controls for systems in accessible locations
• Review and strengthen endpoint protection policies to detect and prevent privilege escalation attempts

Patch Information

Dell has released BIOS firmware updates to address this vulnerability. Organizations should consult the Dell Security Advisory SLN321726 to identify the specific firmware versions required for their deployed hardware models.

Due to the extensive list of affected products spanning multiple Dell product families (Latitude, Optiplex, Precision, Inspiron, Vostro, XPS, G-series, and Wyse), administrators should use Dell Command Update, Dell Update Catalog, or direct downloads from Dell Support to obtain the appropriate BIOS updates.

BIOS updates should be tested in a representative environment before broad deployment and applied through established firmware update procedures.

Workarounds

• Limit local administrator access to essential personnel and monitor administrator account usage
• Implement application control policies to restrict which processes can interact with system management interfaces
• Enable chassis intrusion detection where available to alert on physical access attempts
• Configure BIOS boot passwords as an additional authentication layer (separate from BIOS Administrator password)
• Deploy endpoint detection and response solutions to identify suspicious local privilege escalation or system management API abuse

# Example: Using Dell Command Configure to verify BIOS settings
# Check current BIOS Administrator password status
cctk --BiosAdmin

# Export current BIOS configuration for baseline comparison
cctk --export=bios_baseline.txt

# Monitor for configuration drift against established baseline