[New rule] Remote Computer Account DnsHostName Update (elastic#1962)

* [New rule] Remote Computer Account DnsHostName Update Identifies remote update to a computer account DnsHostName attribute, if the new value is set a valid domain controller DNS hostname and the subject computer name is not a domain controller then it's high likely a preparation step to exploit CVE-2022-26923 in an attempt to elevate privileges from a standard domain user to domain admin privileges : * added MS ref url * Update rules/windows/privilege_escalation_suspicious_dnshostname_update.toml Co-authored-by: Jonhnathan <[email protected]> * Update rules/windows/privilege_escalation_suspicious_dnshostname_update.toml Co-authored-by: Jonhnathan <[email protected]> Co-authored-by: Jonhnathan <[email protected]>
joepeeples · May 11, 2022 · 19ff825 · 19ff825
1 parent 5f447a6
commit 19ff825
Show file tree

Hide file tree

Showing 2 changed files with 67 additions and 1 deletion.
diff --git a/detection_rules/etc/non-ecs-schema.json b/detection_rules/etc/non-ecs-schema.json
@@ -39,7 +39,8 @@
         "TargetSid": "keyword", 
 	"PrivilegeList": "keyword",
 	"AuthenticationPackageName" : "keyword",
-	"TargetUserSid" : "keyword"
+	"TargetUserSid" : "keyword",
+	"DnsHostName" : "keyword"
       }
     },
     "winlog.logon.type": "keyword",

diff --git a/rules/windows/privilege_escalation_suspicious_dnshostname_update.toml b/rules/windows/privilege_escalation_suspicious_dnshostname_update.toml
@@ -0,0 +1,65 @@
+[metadata]
+creation_date = "2022/05/11"
+maturity = "production"
+updated_date = "2022/05/11"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies the remote update to a computer account's DnsHostName attribute. If the new value set is a valid domain
+controller DNS hostname and the subject computer name is not a domain controller, then it's highly likely a preparation
+step to exploit CVE-2022-26923 in an attempt to elevate privileges from a standard domain user to domain admin privileges.
+"""
+from = "now-9m"
+index = ["winlogbeat-*", "logs-system.*"]
+language = "eql"
+license = "Elastic License v2"
+name = "Remote Computer Account DnsHostName Update"
+references = [
+    "https://research.ifcr.dk/certifried-active-directory-domain-privilege-escalation-cve-2022-26923-9e098fe298f4",
+    "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2022-26923",
+]
+risk_score = 73
+rule_id = "6bed021a-0afb-461c-acbe-ffdb9574d3f3"
+severity = "high"
+tags = ["Elastic", "Host", "Windows", "Threat Detection", "Privilege Escalation", "Active Directory"]
+type = "eql"
+
+query = '''
+sequence by host.id with maxspan=5m
+
+  [authentication where event.action == "logged-in" and
+   winlog.logon.type == "Network" and event.outcome == "success" and
+   not user.name == "ANONYMOUS LOGON" and not winlog.event_data.SubjectUserName : "*$" and
+   not user.domain == "NT AUTHORITY" and source.ip != "127.0.0.1" and source.ip !="::1"] by winlog.event_data.TargetLogonId
+
+  [iam where event.action == "changed-computer-account" and
+
+   /* if DnsHostName value equal a DC DNS hostname then it's highly suspicious */
+    winlog.event_data.DnsHostName : "??*"] by winlog.event_data.SubjectLogonId
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1068"
+name = "Exploitation for Privilege Escalation"
+reference = "https://attack.mitre.org/techniques/T1068/"
+
+[[rule.threat.technique]]
+id = "T1078"
+name = "Valid Accounts"
+reference = "https://attack.mitre.org/techniques/T1078/"
+[[rule.threat.technique.subtechnique]]
+id = "T1078.002"
+name = "Domain Accounts"
+reference = "https://attack.mitre.org/techniques/T1078/002/"
+
+
+
+[rule.threat.tactic]
+id = "TA0004"
+name = "Privilege Escalation"
+reference = "https://attack.mitre.org/tactics/TA0004/"
+