CVE-2020-7280 in Virus Scan Enterprise
Summary
by MITRE
Privilege Escalation vulnerability during daily DAT updates when using McAfee Virus Scan Enterprise (VSE) prior to 8.8 Patch 15 allows local users to cause the deletion and creation of files they would not normally have permission to through altering the target of symbolic links. This is timing dependent.
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Analysis
by VulDB Data Team • 10/24/2020
The CVE-2020-7280 vulnerability represents a critical privilege escalation flaw within McAfee Virus Scan Enterprise versions prior to 8.8 Patch 15, specifically manifesting during the daily DAT (Definition) update process. This vulnerability exploits a timing-dependent race condition that occurs when the antivirus software processes symbolic link modifications during routine updates. The flaw stems from insufficient validation of symbolic link targets within the update mechanism, allowing local attackers to manipulate file system operations through carefully crafted symbolic link alterations. The vulnerability operates within the context of the McAfee VSE service execution environment, where the software performs administrative operations on behalf of the system, creating an opportunity for privilege escalation from user-level access to elevated system privileges.
The technical implementation of this vulnerability involves a classic race condition scenario where the system's handling of symbolic links during DAT updates creates a window of opportunity for exploitation. When McAfee VSE processes updates, it traverses symbolic link structures to locate and modify definition files, but fails to properly validate the target destinations of these links before performing file operations. This weakness enables attackers to create malicious symbolic links that point to sensitive system files or directories, then manipulate the update process to execute operations against these targets instead of the intended locations. The timing aspect is crucial as attackers must synchronize their symbolic link creation and modification with the specific moments when the update process accesses these links, typically occurring during the daily scheduled DAT update window. This vulnerability is classified under CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, demonstrating how improper resource access control during concurrent operations can lead to security breaches.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security model of the McAfee VSE platform and potentially compromises the entire system integrity. An attacker who successfully exploits this vulnerability can not only delete or create files in restricted locations but also potentially modify critical system components, logs, or configuration files that would normally require administrative privileges to alter. This capability allows for persistent access, data manipulation, or the installation of malicious components that can evade detection by the very antivirus software that should be protecting the system. The vulnerability particularly affects enterprise environments where McAfee VSE is deployed, as it can be leveraged to gain unauthorized access to sensitive corporate data and systems. The timing-dependent nature of the exploit requires attackers to have system access and knowledge of the update schedules, but once successful, the consequences can be severe and long-lasting.
Mitigation strategies for CVE-2020-7280 primarily focus on applying the vendor-provided patch, specifically McAfee Virus Scan Enterprise 8.8 Patch 15, which addresses the underlying race condition in the DAT update process. Organizations should prioritize immediate deployment of this patch across all affected systems, particularly those running older versions of McAfee VSE. Additional defensive measures include implementing strict file system permissions and monitoring for unauthorized symbolic link creation, especially in directories where antivirus updates occur. System administrators should also consider disabling or restricting automatic DAT updates during peak operational hours to reduce the window of opportunity for exploitation. Network segmentation and principle of least privilege enforcement can further limit the potential impact if exploitation occurs. This vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and demonstrates how seemingly routine system operations can harbor security flaws that enable attackers to elevate their privileges within the target environment. Organizations should also conduct thorough security assessments to identify any potential exploitation attempts and maintain continuous monitoring for unusual file system activities during update windows, as this vulnerability could be used as part of broader attack campaigns targeting enterprise security infrastructure.