[metadata]
creation_date = "2023/01/17"
integration = ["endpoint"]
maturity = "production"
min_stack_comments = "New fields added: dll.Ext.relative_file_creation_time is populated in Elastic Endpoint 8.4 and above."
min_stack_version = "8.4.0"
updated_date = "2023/10/13"

[rule]
author = ["Elastic"]
description = """
Identifies an unsigned library created in the last 5 minutes and subsequently loaded by a shared windows service
(svchost). Adversaries may use this technique to maintain persistence or run with System privileges.
"""
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Unsigned DLL Loaded by Svchost"
risk_score = 47
rule_id = "78ef0c95-9dc2-40ac-a8da-5deb6293a14e"
severity = "medium"
tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Persistence", "Tactic: Defense Evasion", "Tactic: Execution", "Data Source: Elastic Defend"]
timestamp_override = "event.ingested"
type = "eql"

query = '''
library where host.os.type == "windows" and

 process.executable : 
     ("?:\\Windows\\System32\\svchost.exe", "?:\\Windows\\Syswow64\\svchost.exe") and 
     
 dll.code_signature.trusted != true and 
 
 not dll.code_signature.status : ("trusted", "errorExpired", "errorCode_endpoint*") and 
 
 dll.hash.sha256 != null and 
 
 (
       /* DLL created within 5 minutes of the library load event - compatible with Elastic Endpoint 8.4+ */
       dll.Ext.relative_file_creation_time <= 300 or 
   
       /* unusual paths */
       dll.path :("?:\\ProgramData\\*",
                  "?:\\Users\\*",
                  "?:\\PerfLogs\\*",
                  "?:\\Windows\\Tasks\\*",
                  "?:\\Intel\\*",
                  "?:\\AMD\\Temp\\*",
                  "?:\\Windows\\AppReadiness\\*",
                  "?:\\Windows\\ServiceState\\*",
                  "?:\\Windows\\security\\*",
                  "?:\\Windows\\IdentityCRL\\*",
                  "?:\\Windows\\Branding\\*",
                  "?:\\Windows\\csc\\*",
                  "?:\\Windows\\DigitalLocker\\*",
                  "?:\\Windows\\en-US\\*",
                  "?:\\Windows\\wlansvc\\*",
                  "?:\\Windows\\Prefetch\\*",
                  "?:\\Windows\\Fonts\\*",
                  "?:\\Windows\\diagnostics\\*",
                  "?:\\Windows\\TAPI\\*",
                  "?:\\Windows\\INF\\*",
                  "?:\\Windows\\System32\\Speech\\*",
                  "?:\\windows\\tracing\\*",
                  "?:\\windows\\IME\\*",
                  "?:\\Windows\\Performance\\*",
                  "?:\\windows\\intel\\*",
                  "?:\\windows\\ms\\*",
                  "?:\\Windows\\dot3svc\\*",
                  "?:\\Windows\\panther\\*",
                  "?:\\Windows\\RemotePackages\\*",
                  "?:\\Windows\\OCR\\*",
                  "?:\\Windows\\appcompat\\*",
                  "?:\\Windows\\apppatch\\*",
                  "?:\\Windows\\addins\\*",
                  "?:\\Windows\\Setup\\*",
                  "?:\\Windows\\Help\\*",
                  "?:\\Windows\\SKB\\*",
                  "?:\\Windows\\Vss\\*",
                  "?:\\Windows\\servicing\\*",
                  "?:\\Windows\\CbsTemp\\*",
                  "?:\\Windows\\Logs\\*",
                  "?:\\Windows\\WaaS\\*",
                  "?:\\Windows\\twain_32\\*",
                  "?:\\Windows\\ShellExperiences\\*",
                  "?:\\Windows\\ShellComponents\\*",
                  "?:\\Windows\\PLA\\*",
                  "?:\\Windows\\Migration\\*",
                  "?:\\Windows\\debug\\*",
                  "?:\\Windows\\Cursors\\*",
                  "?:\\Windows\\Containers\\*",
                  "?:\\Windows\\Boot\\*",
                  "?:\\Windows\\bcastdvr\\*",
                  "?:\\Windows\\TextInput\\*",
                  "?:\\Windows\\security\\*",
                  "?:\\Windows\\schemas\\*",
                  "?:\\Windows\\SchCache\\*",
                  "?:\\Windows\\Resources\\*",
                  "?:\\Windows\\rescache\\*",
                  "?:\\Windows\\Provisioning\\*",
                  "?:\\Windows\\PrintDialog\\*",
                  "?:\\Windows\\PolicyDefinitions\\*",
                  "?:\\Windows\\media\\*",
                  "?:\\Windows\\Globalization\\*",
                  "?:\\Windows\\L2Schemas\\*",
                  "?:\\Windows\\LiveKernelReports\\*",
                  "?:\\Windows\\ModemLogs\\*",
                  "?:\\Windows\\ImmersiveControlPanel\\*",
                  "?:\\$Recycle.Bin\\*")
  ) and 
  
  not dll.hash.sha256 : 
            ("3ed33e71641645367442e65dca6dab0d326b22b48ef9a4c2a2488e67383aa9a6", 
             "b4db053f6032964df1b254ac44cb995ffaeb4f3ade09597670aba4f172cf65e4", 
             "214c75f678bc596bbe667a3b520aaaf09a0e50c364a28ac738a02f867a085eba", 
             "23aa95b637a1bf6188b386c21c4e87967ede80242327c55447a5bb70d9439244", 
             "5050b025909e81ae5481db37beb807a80c52fc6dd30c8aa47c9f7841e2a31be7")
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1543"
name = "Create or Modify System Process"
reference = "https://attack.mitre.org/techniques/T1543/"
[[rule.threat.technique.subtechnique]]
id = "T1543.003"
name = "Windows Service"
reference = "https://attack.mitre.org/techniques/T1543/003/"



[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"

[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1036"
name = "Masquerading"
reference = "https://attack.mitre.org/techniques/T1036/"

[[rule.threat.technique.subtechnique]]
id = "T1036.001"
name = "Invalid Code Signature"
reference = "https://attack.mitre.org/techniques/T1036/001/"

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

[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1569"
name = "System Services"
reference = "https://attack.mitre.org/techniques/T1569/"
[[rule.threat.technique.subtechnique]]
id = "T1569.002"
name = "Service Execution"
reference = "https://attack.mitre.org/techniques/T1569/002/"



[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"