Microsoft Exploit Guard has blocked an operation

The following warning appears in the Event log:

Log Name: Microsoft-Windows-Windows Defender/Operational

Source:  Windows Defender


Event ID  1121

Microsoft Defender Exploit Guard has blocked an operation that is not allowed by your IT administrator.

 For more information please contact your IT administrator.


     ID: 9E6C4E1F-7D60-472F-BA1A-A39EF669E4B2


     Detection time: 2020-12-11T01:57:18.185Z


     User: XXXXXX-XXXXXX\xxxxxxxxxxx     

Path: C:\Windows\System32\lsass.exe

     Process Name: C:\Program Files\CCleaner\CCleaner64.exe


     Security intelligence Version: 1.329.181.0


     Engine Version: 1.1.17700.4


     Product Version: 4.18.2011.6

My workstation is running

Windows 10 Pro 20H2_19042.685

CCleaner v5.75.8238

Defender for Endpoint has all Attack Surface Reduction rules enabled. The GUID shown in the log entry corresponds to the ASR rule "Block credential stealing from the Windows security authority subsystem (lsass.exe)

What is causing the Exploit Guard to complain about the ASR rule and will this impact the operation of CCleaner or the OS?

Thanks