Hello,I have the same problem now on a windows 2008 R2an attack is going on - it is trying different (non-existing) usernames.this generates 4625, 4776 event ids, but there is no source ip shown.The logon uses NTLM.How can I get the IP to show?An internet post said to block NTLM.I am hesitant to do this, the server warnings seem to suggest that domain computer logon/use will suffer.I don't have access to the external firewall nor its logs - so that does help either.suggestions badly neededbest regards.
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Hi All,Can you please help me to find out the reason of following issue.In our domain after enabling audit we found that huge numbers(around 50k) of Kerberos pre-authentication failed(4771) security failure events are generating in DCs. If any one can explain why this events are generating so frequently. However I found no account lockout has happened. One sample event is as follows.' Kerberos Pre-Authentication errorHi Patrick,I recommend that you log in with the user account which has this issue on the different computer connected to the same Domain and check if it makes any difference.I also recommend that you refer to the article: 4771(F): Kerberos pre-authentication failed for further information on this error.Then I recommend that you post your query in TechNet forums, where the experts with knowledge on the issues connected with Domain computers can provide you with further assistance.
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Enable failed logon auditing (Security Settings Local Policies Audit Policy Audit Logon Events) in. I believe the only type of failure that will lead to a lockout is 0x24 (bad password), but I could be wrong. You can track all 4771 events where the Client Address is not from your internal IP range or not from private IP ranges. If you know that Account Name should be used only from known list of IP addresses, track all Client Address values for this Account Name in 4771 events. If Client Address is not from the whitelist, generate the alert. All Client Address =::1 means local authentication.
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February 2023
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