Vulnerability in McAfee Antivirus Software

McAfee patched a Privilege Escalation vulnerability in Microsoft Windows client versions of all McAfee Antivirus versions that allow administrators to execute arbitrary code and escalate to SYSTEM privileges.

 

The vulnerability gives attackers an ability to load and execute malicious payloads using multiple signed services in a persistent way within the context of McAfee’s signed processes.

 

The system account is the internal account used by the Windows operating system to manage the services that run under Windows.

 

The vulnerability affects Microsoft Windows client in McAfee Total Protection, McAfee Anti-Virus Plus, and McAfee Internet Security, 16.0.R22 and earlier.

 

Escalation Vulnerability Discovery

 

The vulnerability was discovered by SafeBreach Labs in all the editions of McAfee Antivirus software. To exploit this vulnerability the attacker needs to be a system administrator.

 

“This vulnerability could be used by an attacker to bypass McAfee’s Self-Defense mechanism, evade defense and achieve persistence by loading multiple services that run as NT AUTHORITYSYSTEM.”

 

Trying to load from System32Wbem

 

With the Anti-virus software, multiple parts run as a Windows service executed by “NT AUTHORITYSYSTEM,” which has SYSTEM permission.

 

Researchers found that McAfee Antivirus software which runs as a signed process and as NT AUTHORITYSYSTEM tries to load the wbemcomn.dll file from location (c:WindowsSystem32wbemwbemcomn.dll) whereas the file present under System32 and not with System32Wbem folder.

 

This allows researchers to load an unsigned arbitrary DLL to load in the process and to bypass the self-defense mechanism of the Antivirus software. “This is mainly because the folders of the McAfee software are protected by a mini-filter filesystem driver, which restricts writing operations even by an Administrator.”

 

The vulnerability can be tracked as CVE-2019-3648 and it was reported to McAfee on Aug 5th, 2019, it has been patched now and McAfee urges users to update with 16.0.R22 Refresh 1 version that fixes the privilege escalation vulnerability.

 

This is not the first time like McAfee Hadar reported privilege escalation vulnerability in other security vendors such as Avast Antivirus, AVG Antivirus, Trend Micro and Check Point Endpoint security.