The following analytic leverages Windows Security Event 4738,
A user account was changed, to identify a change performed on a domain user object that disables Kerberos Pre-Authentication. Disabling the Pre Authentication flag in the UserAccountControl property allows an adversary to easily perform a brute force attack against the user's password offline leveraging the ASP REP Roasting technique. Red Teams and adversaries alike who have obtained privileges in an Active Directory network may use this technique as a backdoor or a way to escalate privileges.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-02-22
- Author: Mauricio Velazco, Splunk
- ID: 0cb847ee-9423-11ec-b2df-acde48001122
Kill Chain Phase
1 2 3 `wineventlog_security` EventCode=4738 MSADChangedAttributes="*Don't Require Preauth' - Enabled*" | table EventCode, Account_Name, Security_ID, MSADChangedAttributes | `kerberos_pre_authentication_flag_disabled_in_useraccountcontrol_filter`
The SPL above uses the following Macros:
kerberos_pre-authentication_flag_disabled_in_useraccountcontrol_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting Domain Controller events. The Advanced Security Audit policy setting
User Account Management within
Account Management needs to be enabled.
Known False Positives
Associated Analytic Story
|45.0||50||90||Kerberos Pre Authentication was Disabled for $Account_Name$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1