Unsigned DLL Loaded by Svchost

  1[metadata]
  2creation_date = "2023/01/17"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/05/21"
  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"
 18risk_score = 47
 19rule_id = "78ef0c95-9dc2-40ac-a8da-5deb6293a14e"
 20severity = "medium"
 21tags = [
 22    "Domain: Endpoint",
 23    "OS: Windows",
 24    "Use Case: Threat Detection",
 25    "Tactic: Persistence",
 26    "Tactic: Defense Evasion",
 27    "Tactic: Execution",
 28    "Data Source: Elastic Defend",
 29]
 30timestamp_override = "event.ingested"
 31type = "eql"
 32
 33query = '''
 34library where host.os.type == "windows" and
 35
 36 process.executable : 
 37     ("?:\\Windows\\System32\\svchost.exe", "?:\\Windows\\Syswow64\\svchost.exe") and 
 38     
 39 dll.code_signature.trusted != true and 
 40 
 41 not dll.code_signature.status : ("trusted", "errorExpired", "errorCode_endpoint*") and 
 42 
 43 dll.hash.sha256 != null and 
 44 
 45 (
 46       /* DLL created within 5 minutes of the library load event - compatible with Elastic Endpoint 8.4+ */
 47       dll.Ext.relative_file_creation_time <= 300 or 
 48   
 49       /* unusual paths */
 50       dll.path :("?:\\ProgramData\\*",
 51                  "?:\\Users\\*",
 52                  "?:\\PerfLogs\\*",
 53                  "?:\\Windows\\Tasks\\*",
 54                  "?:\\Intel\\*",
 55                  "?:\\AMD\\Temp\\*",
 56                  "?:\\Windows\\AppReadiness\\*",
 57                  "?:\\Windows\\ServiceState\\*",
 58                  "?:\\Windows\\security\\*",
 59                  "?:\\Windows\\IdentityCRL\\*",
 60                  "?:\\Windows\\Branding\\*",
 61                  "?:\\Windows\\csc\\*",
 62                  "?:\\Windows\\DigitalLocker\\*",
 63                  "?:\\Windows\\en-US\\*",
 64                  "?:\\Windows\\wlansvc\\*",
 65                  "?:\\Windows\\Prefetch\\*",
 66                  "?:\\Windows\\Fonts\\*",
 67                  "?:\\Windows\\diagnostics\\*",
 68                  "?:\\Windows\\TAPI\\*",
 69                  "?:\\Windows\\INF\\*",
 70                  "?:\\Windows\\System32\\Speech\\*",
 71                  "?:\\windows\\tracing\\*",
 72                  "?:\\windows\\IME\\*",
 73                  "?:\\Windows\\Performance\\*",
 74                  "?:\\windows\\intel\\*",
 75                  "?:\\windows\\ms\\*",
 76                  "?:\\Windows\\dot3svc\\*",
 77                  "?:\\Windows\\panther\\*",
 78                  "?:\\Windows\\RemotePackages\\*",
 79                  "?:\\Windows\\OCR\\*",
 80                  "?:\\Windows\\appcompat\\*",
 81                  "?:\\Windows\\apppatch\\*",
 82                  "?:\\Windows\\addins\\*",
 83                  "?:\\Windows\\Setup\\*",
 84                  "?:\\Windows\\Help\\*",
 85                  "?:\\Windows\\SKB\\*",
 86                  "?:\\Windows\\Vss\\*",
 87                  "?:\\Windows\\servicing\\*",
 88                  "?:\\Windows\\CbsTemp\\*",
 89                  "?:\\Windows\\Logs\\*",
 90                  "?:\\Windows\\WaaS\\*",
 91                  "?:\\Windows\\twain_32\\*",
 92                  "?:\\Windows\\ShellExperiences\\*",
 93                  "?:\\Windows\\ShellComponents\\*",
 94                  "?:\\Windows\\PLA\\*",
 95                  "?:\\Windows\\Migration\\*",
 96                  "?:\\Windows\\debug\\*",
 97                  "?:\\Windows\\Cursors\\*",
 98                  "?:\\Windows\\Containers\\*",
 99                  "?:\\Windows\\Boot\\*",
100                  "?:\\Windows\\bcastdvr\\*",
101                  "?:\\Windows\\TextInput\\*",
102                  "?:\\Windows\\security\\*",
103                  "?:\\Windows\\schemas\\*",
104                  "?:\\Windows\\SchCache\\*",
105                  "?:\\Windows\\Resources\\*",
106                  "?:\\Windows\\rescache\\*",
107                  "?:\\Windows\\Provisioning\\*",
108                  "?:\\Windows\\PrintDialog\\*",
109                  "?:\\Windows\\PolicyDefinitions\\*",
110                  "?:\\Windows\\media\\*",
111                  "?:\\Windows\\Globalization\\*",
112                  "?:\\Windows\\L2Schemas\\*",
113                  "?:\\Windows\\LiveKernelReports\\*",
114                  "?:\\Windows\\ModemLogs\\*",
115                  "?:\\Windows\\ImmersiveControlPanel\\*",
116                  "?:\\$Recycle.Bin\\*")
117  ) and 
118  
119  not dll.hash.sha256 : 
120            ("3ed33e71641645367442e65dca6dab0d326b22b48ef9a4c2a2488e67383aa9a6", 
121             "b4db053f6032964df1b254ac44cb995ffaeb4f3ade09597670aba4f172cf65e4", 
122             "214c75f678bc596bbe667a3b520aaaf09a0e50c364a28ac738a02f867a085eba", 
123             "23aa95b637a1bf6188b386c21c4e87967ede80242327c55447a5bb70d9439244", 
124             "5050b025909e81ae5481db37beb807a80c52fc6dd30c8aa47c9f7841e2a31be7")
125'''
126
127
128[[rule.threat]]
129framework = "MITRE ATT&CK"
130[[rule.threat.technique]]
131id = "T1543"
132name = "Create or Modify System Process"
133reference = "https://attack.mitre.org/techniques/T1543/"
134[[rule.threat.technique.subtechnique]]
135id = "T1543.003"
136name = "Windows Service"
137reference = "https://attack.mitre.org/techniques/T1543/003/"
138
139
140
141[rule.threat.tactic]
142id = "TA0003"
143name = "Persistence"
144reference = "https://attack.mitre.org/tactics/TA0003/"
145[[rule.threat]]
146framework = "MITRE ATT&CK"
147[[rule.threat.technique]]
148id = "T1036"
149name = "Masquerading"
150reference = "https://attack.mitre.org/techniques/T1036/"
151[[rule.threat.technique.subtechnique]]
152id = "T1036.001"
153name = "Invalid Code Signature"
154reference = "https://attack.mitre.org/techniques/T1036/001/"
155
156
157
158[rule.threat.tactic]
159id = "TA0005"
160name = "Defense Evasion"
161reference = "https://attack.mitre.org/tactics/TA0005/"
162[[rule.threat]]
163framework = "MITRE ATT&CK"
164[[rule.threat.technique]]
165id = "T1569"
166name = "System Services"
167reference = "https://attack.mitre.org/techniques/T1569/"
168[[rule.threat.technique.subtechnique]]
169id = "T1569.002"
170name = "Service Execution"
171reference = "https://attack.mitre.org/techniques/T1569/002/"
172
173
174
175[rule.threat.tactic]
176id = "TA0002"
177name = "Execution"
178reference = "https://attack.mitre.org/tactics/TA0002/"