ROT Encoded Python Script Execution

 1[metadata]
 2creation_date = "2024/09/17"
 3integration = ["endpoint"]
 4maturity = "production"
 5updated_date = "2024/09/17"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10Identifies the execution of a Python script that uses the ROT cipher for letters substitution. Adversaries may
11use this method to encode and obfuscate part of their malicious code in legit python packages.
12"""
13from = "now-9m"
14index = ["logs-endpoint.events.process-*", "logs-endpoint.events.file-*"]
15language = "eql"
16license = "Elastic License v2"
17name = "ROT Encoded Python Script Execution"
18references = [
19    "https://www.elastic.co/security-labs/dprk-code-of-conduct",
20    "https://www.reversinglabs.com/blog/fake-recruiter-coding-tests-target-devs-with-malicious-python-packages"
21]
22risk_score = 47
23rule_id = "5ab49127-b1b3-46e6-8a38-9e8512a2a363"
24severity = "medium"
25tags = [
26    "Domain: Endpoint",
27    "OS: Windows",
28    "OS: macOS",
29    "Use Case: Threat Detection",
30    "Tactic: Defense Evasion",
31    "Data Source: Elastic Defend",
32]
33type = "eql"
34
35query = '''
36sequence by process.entity_id with maxspan=1m
37 [process where host.os.type in ("windows", "macos") and event.type == "start" and process.name : "python*"]
38 [file where host.os.type in ("windows", "macos") and
39  event.action != "deletion" and process.name : "python*" and file.name : "rot_??.cpython-*.pyc*"]
40'''
41
42
43[[rule.threat]]
44framework = "MITRE ATT&CK"
45[[rule.threat.technique]]
46id = "T1140"
47name = "Deobfuscate/Decode Files or Information"
48reference = "https://attack.mitre.org/techniques/T1140/"
49[[rule.threat.technique]]
50id = "T1027"
51name = "Obfuscated Files or Information"
52reference = "https://attack.mitre.org/techniques/T1027/"
53[[rule.threat.technique.subtechnique]]
54id = "T1027.013"
55name = "Encrypted/Encoded File"
56reference = "https://attack.mitre.org/techniques/T1027/013/"
57
58
59[rule.threat.tactic]
60id = "TA0005"
61name = "Defense Evasion"
62reference = "https://attack.mitre.org/tactics/TA0005/"