Suspicious Data Encryption via OpenSSL Utility

 1[metadata]
 2creation_date = "2023/06/26"
 3integration = ["endpoint"]
 4maturity = "production"
 5min_stack_comments = "New fields added: required_fields, related_integrations, setup"
 6min_stack_version = "8.3.0"
 7updated_date = "2023/06/26"
 8
 9[rule]
10author = ["Elastic"]
11description = """
12Identifies when the openssl command-line utility is used to encrypt multiple files on a host within a short time window.
13Adversaries may encrypt data on a single or multiple systems in order to disrupt the availability of their target's data
14and may attempt to hold the organization's data to ransom for the purposes of extortion.
15"""
16from = "now-9m"
17index = ["logs-endpoint.events.*"]
18language = "eql"
19license = "Elastic License v2"
20name = "Suspicious Data Encryption via OpenSSL Utility"
21references = [
22  "https://www.welivesecurity.com/2017/06/30/telebots-back-supply-chain-attacks-against-ukraine/",
23  "https://www.trendmicro.com/en_us/research/21/f/bash-ransomware-darkradiation-targets-red-hat--and-debian-based-linux-distributions.html",
24]
25risk_score = 47
26rule_id = "f530ca17-153b-4a7a-8cd3-98dd4b4ddf73"
27severity = "medium"
28tags = ["Domain: Endpoint", "OS: Linux", "Use Case: Threat Detection", "Tactic: Impact", "Data Source: Elastic Defend"]
29type = "eql"
30query = '''
31sequence by host.id, user.name, process.parent.entity_id with maxspan=5s
32  [ process where host.os.type == "linux" and event.action == "exec" and 
33    process.name == "openssl" and process.parent.name : ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "perl*", "php*", "python*", "xargs") and
34    process.args == "-in" and process.args == "-out" and
35    process.args in ("-k", "-K", "-kfile", "-pass", "-iv", "-md") and
36    /* excluding base64 encoding options and including encryption password or key params */
37    not process.args in ("-d", "-a", "-A", "-base64", "-none", "-nosalt") ] with runs=10
38'''
39
40[[rule.threat]]
41framework = "MITRE ATT&CK"
42
43[rule.threat.tactic]
44name = "Impact"
45id = "TA0040"
46reference = "https://attack.mitre.org/tactics/TA0040/"
47
48[[rule.threat.technique]]
49name = "Data Encrypted for Impact"
50id = "T1486"
51reference = "https://attack.mitre.org/techniques/T1486/"