File Execution via Microsoft HTML Help

[rule]
description = """
Identifies when the Microsoft HTML Help Executable (hh.exe) creates a portable executable (PE) file and the file is
subsequently executed. Adversaries may conceal malicious code in a CHM file and deliver it to a victim for execution.
"""
id = "9c3b13f6-bc26-4397-9721-4ba23ddd1014"
license = "Elastic License v2"
name = "File Execution via Microsoft HTML Help"
os_list = ["windows"]
reference = [
    "https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/higaisa-or-winnti-apt-41-backdoors-old-and-new/",
]
version = "1.0.30"

query = '''
sequence with maxspan=2m
 [file where event.action != "deletion" and process.name : "hh.exe"] by file.path
 [process where event.action == "start"] by process.executable
'''

min_endpoint_version = "7.15.0"
optional_actions = []
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 1

[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1566"
name = "Phishing"
reference = "https://attack.mitre.org/techniques/T1566/"
[[threat.technique.subtechnique]]
id = "T1566.001"
name = "Spearphishing Attachment"
reference = "https://attack.mitre.org/techniques/T1566/001/"



[threat.tactic]
id = "TA0001"
name = "Initial Access"
reference = "https://attack.mitre.org/tactics/TA0001/"
[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1218"
name = "System Binary Proxy Execution"
reference = "https://attack.mitre.org/techniques/T1218/"
[[threat.technique.subtechnique]]
id = "T1218.001"
name = "Compiled HTML File"
reference = "https://attack.mitre.org/techniques/T1218/001/"



[threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"

[internal]
min_endpoint_version = "7.15.0"