[New] Potential Foxmail Exploitation (elastic#4044)

* Create execution_initial_access_foxmail_exploit.toml

* Update execution_initial_access_foxmail_exploit.toml

---------

Co-authored-by: Colson Wilhoit <[email protected]>

rules/windows/execution_initial_access_foxmail_exploit.toml

@@ -0,0 +1,78 @@
+[metadata]
+creation_date = "2024/08/29"
+integration = ["endpoint", "windows", "system", "sentinel_one_cloud_funnel", "m365_defender"]
+maturity = "production"
+updated_date = "2024/09/16"
+
+[rule]
+author = ["Elastic"]
+description = """
+Identifies the Foxmail client spawning a child process with argument pointing to the Foxmail temp directory. 
+This may indicate the successful exploitation of a Foxmail vulnerability for initial access and execution via 
+a malicious email.
+"""
+from = "now-9m"
+index = [
+    "winlogbeat-*",
+    "logs-windows.*",
+    "endgame-*",
+    "logs-system.security*",
+    "logs-windows.sysmon_operational-*",
+    "logs-sentinel_one_cloud_funnel.*",
+    "logs-m365_defender.event-*", 
+    "logs-endpoint.events.process-*"
+]
+language = "eql"
+license = "Elastic License v2"
+name = "Potential Foxmail Exploitation"
+references = ["https://mp.weixin.qq.com/s/F8hNyESBdKhwXkQPgtGpew"]
+risk_score = 73
+rule_id = "2c6a6acf-0dcb-404d-89fb-6b0327294cfa"
+severity = "high"
+tags = [
+    "Domain: Endpoint",
+    "OS: Windows",
+    "Use Case: Threat Detection",
+    "Tactic: Initial Access",
+    "Tactic: Execution",
+    "Data Source: Elastic Defend",
+    "Data Source: Sysmon", 
+    "Data Source: System", 
+    "Data Source: Elastic Endgame",
+    "Data Source: SentinelOne",
+    "Data Source: Microsoft Defender for Endpoint"
+]
+timestamp_override = "event.ingested"
+type = "eql"
+
+query = '''
+process where host.os.type == "windows" and event.type == "start" and 
+ process.parent.name : "Foxmail.exe" and process.args : ("?:\\Users\\*\\AppData\\*", "\\\\*")
+
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1203"
+name = "Exploitation for Client Execution"
+reference = "https://attack.mitre.org/techniques/T1203/"
+
+
+[rule.threat.tactic]
+id = "TA0002"
+name = "Execution"
+reference = "https://attack.mitre.org/tactics/TA0002/"
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1189"
+name = "Drive-by Compromise"
+reference = "https://attack.mitre.org/techniques/T1189/"
+
+
+[rule.threat.tactic]
+id = "TA0001"
+name = "Initial Access"
+reference = "https://attack.mitre.org/tactics/TA0001/"