Unsigned DLL Loaded by Svchost

  1[metadata]
  2creation_date = "2023/01/17"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/09/23"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Identifies an unsigned library created in the last 5 minutes and subsequently loaded by a shared windows service
 11(svchost). Adversaries may use this technique to maintain persistence or run with System privileges.
 12"""
 13from = "now-9m"
 14index = ["logs-endpoint.events.library-*"]
 15language = "eql"
 16license = "Elastic License v2"
 17name = "Unsigned DLL Loaded by Svchost"
 18references = [
 19    "https://www.elastic.co/security-labs/Hunting-for-Suspicious-Windows-Libraries-for-Execution-and-Evasion",
 20]
 21risk_score = 47
 22rule_id = "78ef0c95-9dc2-40ac-a8da-5deb6293a14e"
 23severity = "medium"
 24tags = [
 25    "Domain: Endpoint",
 26    "OS: Windows",
 27    "Use Case: Threat Detection",
 28    "Tactic: Persistence",
 29    "Tactic: Defense Evasion",
 30    "Tactic: Execution",
 31    "Data Source: Elastic Defend",
 32]
 33timestamp_override = "event.ingested"
 34type = "eql"
 35
 36query = '''
 37library where host.os.type == "windows" and
 38
 39 process.executable : 
 40     ("?:\\Windows\\System32\\svchost.exe", "?:\\Windows\\Syswow64\\svchost.exe") and 
 41     
 42 dll.code_signature.trusted != true and 
 43 
 44 not dll.code_signature.status : ("trusted", "errorExpired", "errorCode_endpoint*") and 
 45 
 46 dll.hash.sha256 != null and 
 47 
 48 (
 49       /* DLL created within 5 minutes of the library load event - compatible with Elastic Endpoint 8.4+ */
 50       dll.Ext.relative_file_creation_time <= 300 or 
 51   
 52       /* unusual paths */
 53       dll.path :("?:\\ProgramData\\*",
 54                  "?:\\Users\\*",
 55                  "?:\\PerfLogs\\*",
 56                  "?:\\Windows\\Tasks\\*",
 57                  "?:\\Intel\\*",
 58                  "?:\\AMD\\Temp\\*",
 59                  "?:\\Windows\\AppReadiness\\*",
 60                  "?:\\Windows\\ServiceState\\*",
 61                  "?:\\Windows\\security\\*",
 62                  "?:\\Windows\\IdentityCRL\\*",
 63                  "?:\\Windows\\Branding\\*",
 64                  "?:\\Windows\\csc\\*",
 65                  "?:\\Windows\\DigitalLocker\\*",
 66                  "?:\\Windows\\en-US\\*",
 67                  "?:\\Windows\\wlansvc\\*",
 68                  "?:\\Windows\\Prefetch\\*",
 69                  "?:\\Windows\\Fonts\\*",
 70                  "?:\\Windows\\diagnostics\\*",
 71                  "?:\\Windows\\TAPI\\*",
 72                  "?:\\Windows\\INF\\*",
 73                  "?:\\Windows\\System32\\Speech\\*",
 74                  "?:\\windows\\tracing\\*",
 75                  "?:\\windows\\IME\\*",
 76                  "?:\\Windows\\Performance\\*",
 77                  "?:\\windows\\intel\\*",
 78                  "?:\\windows\\ms\\*",
 79                  "?:\\Windows\\dot3svc\\*",
 80                  "?:\\Windows\\panther\\*",
 81                  "?:\\Windows\\RemotePackages\\*",
 82                  "?:\\Windows\\OCR\\*",
 83                  "?:\\Windows\\appcompat\\*",
 84                  "?:\\Windows\\apppatch\\*",
 85                  "?:\\Windows\\addins\\*",
 86                  "?:\\Windows\\Setup\\*",
 87                  "?:\\Windows\\Help\\*",
 88                  "?:\\Windows\\SKB\\*",
 89                  "?:\\Windows\\Vss\\*",
 90                  "?:\\Windows\\servicing\\*",
 91                  "?:\\Windows\\CbsTemp\\*",
 92                  "?:\\Windows\\Logs\\*",
 93                  "?:\\Windows\\WaaS\\*",
 94                  "?:\\Windows\\twain_32\\*",
 95                  "?:\\Windows\\ShellExperiences\\*",
 96                  "?:\\Windows\\ShellComponents\\*",
 97                  "?:\\Windows\\PLA\\*",
 98                  "?:\\Windows\\Migration\\*",
 99                  "?:\\Windows\\debug\\*",
100                  "?:\\Windows\\Cursors\\*",
101                  "?:\\Windows\\Containers\\*",
102                  "?:\\Windows\\Boot\\*",
103                  "?:\\Windows\\bcastdvr\\*",
104                  "?:\\Windows\\TextInput\\*",
105                  "?:\\Windows\\security\\*",
106                  "?:\\Windows\\schemas\\*",
107                  "?:\\Windows\\SchCache\\*",
108                  "?:\\Windows\\Resources\\*",
109                  "?:\\Windows\\rescache\\*",
110                  "?:\\Windows\\Provisioning\\*",
111                  "?:\\Windows\\PrintDialog\\*",
112                  "?:\\Windows\\PolicyDefinitions\\*",
113                  "?:\\Windows\\media\\*",
114                  "?:\\Windows\\Globalization\\*",
115                  "?:\\Windows\\L2Schemas\\*",
116                  "?:\\Windows\\LiveKernelReports\\*",
117                  "?:\\Windows\\ModemLogs\\*",
118                  "?:\\Windows\\ImmersiveControlPanel\\*",
119                  "?:\\$Recycle.Bin\\*")
120  ) and 
121  
122  not dll.hash.sha256 : 
123            ("3ed33e71641645367442e65dca6dab0d326b22b48ef9a4c2a2488e67383aa9a6", 
124             "b4db053f6032964df1b254ac44cb995ffaeb4f3ade09597670aba4f172cf65e4", 
125             "214c75f678bc596bbe667a3b520aaaf09a0e50c364a28ac738a02f867a085eba", 
126             "23aa95b637a1bf6188b386c21c4e87967ede80242327c55447a5bb70d9439244", 
127             "5050b025909e81ae5481db37beb807a80c52fc6dd30c8aa47c9f7841e2a31be7")
128'''
129
130
131[[rule.threat]]
132framework = "MITRE ATT&CK"
133[[rule.threat.technique]]
134id = "T1543"
135name = "Create or Modify System Process"
136reference = "https://attack.mitre.org/techniques/T1543/"
137[[rule.threat.technique.subtechnique]]
138id = "T1543.003"
139name = "Windows Service"
140reference = "https://attack.mitre.org/techniques/T1543/003/"
141
142
143
144[rule.threat.tactic]
145id = "TA0003"
146name = "Persistence"
147reference = "https://attack.mitre.org/tactics/TA0003/"
148[[rule.threat]]
149framework = "MITRE ATT&CK"
150[[rule.threat.technique]]
151id = "T1036"
152name = "Masquerading"
153reference = "https://attack.mitre.org/techniques/T1036/"
154[[rule.threat.technique.subtechnique]]
155id = "T1036.001"
156name = "Invalid Code Signature"
157reference = "https://attack.mitre.org/techniques/T1036/001/"
158
159
160
161[rule.threat.tactic]
162id = "TA0005"
163name = "Defense Evasion"
164reference = "https://attack.mitre.org/tactics/TA0005/"
165[[rule.threat]]
166framework = "MITRE ATT&CK"
167[[rule.threat.technique]]
168id = "T1569"
169name = "System Services"
170reference = "https://attack.mitre.org/techniques/T1569/"
171[[rule.threat.technique.subtechnique]]
172id = "T1569.002"
173name = "Service Execution"
174reference = "https://attack.mitre.org/techniques/T1569/002/"
175
176
177
178[rule.threat.tactic]
179id = "TA0002"
180name = "Execution"
181reference = "https://attack.mitre.org/tactics/TA0002/"