Unusual Process Network Connection

  1[metadata]
  2creation_date = "2020/02/18"
  3integration = ["endpoint", "windows", "sentinel_one_cloud_funnel"]
  4maturity = "production"
  5updated_date = "2026/09/18"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Identifies network activity from unexpected system applications. This may indicate adversarial activity as these
 11applications are often leveraged by adversaries to execute code and evade detection.
 12"""
 13from = "now-9m"
 14index = [
 15    "winlogbeat-*",
 16    "logs-endpoint.events.process-*",
 17    "logs-endpoint.events.network-*",
 18    "logs-windows.sysmon_operational-*",
 19    "logs-sentinel_one_cloud_funnel.*",
 20]
 21language = "eql"
 22license = "Elastic License v2"
 23name = "Unusual Process Network Connection"
 24note = """## Triage and analysis
 25
 26### Investigating Unusual Process Network Connection
 27
 28This rule identifies network activity from unexpected system utilities and applications. These applications are commonly abused by attackers to execute code, evade detections, and bypass security protections.
 29
 30#### Possible investigation steps
 31
 32- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
 33- Investigate other alerts associated with the user/host during the past 48 hours.
 34- Investigate the target host that the process is communicating with.
 35- Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts.
 36
 37### False positive analysis
 38
 39- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
 40
 41### Response and remediation
 42
 43- Initiate the incident response process based on the outcome of the triage.
 44- Isolate the involved hosts to prevent further post-compromise behavior.
 45- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
 46- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 47- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 48- Review the privileges assigned to the user to ensure that the least privilege principle is being followed.
 49- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
 50"""
 51
 52setup = """## Setup
 53
 54This rule is designed for data generated by [Elastic Defend](https://www.elastic.co/security/endpoint-security), which provides native endpoint detection and response, along with event enrichments designed to work with our detection rules.
 55
 56Setup instructions: https://ela.st/install-elastic-defend
 57
 58### Additional data sources
 59
 60This rule also supports the following third-party data sources. For setup instructions, refer to the links below:
 61
 62- [SentinelOne Cloud Funnel](https://ela.st/sentinel-one-cloud-funnel)
 63- [Sysmon Event ID 1 - Process Creation](https://ela.st/sysmon-event-1-setup)
 64- [Sysmon Event ID 3 - Network Connection](https://ela.st/sysmon-event-3-setup)
 65"""
 66
 67risk_score = 21
 68rule_id = "610949a1-312f-4e04-bb55-3a79b8c95267"
 69severity = "low"
 70tags = [
 71    "Domain: Endpoint",
 72    "OS: Windows",
 73    "Use Case: Threat Detection",
 74    "Tactic: Defense Evasion",
 75    "Resources: Investigation Guide",
 76    "Data Source: Elastic Defend",
 77    "Data Source: Sysmon",
 78    "Data Source: SentinelOne",
 79    "Noise: Medium",
 80    "Performance: Normal",
 81    "Threat: Living off the Land",
 82    "Rule Type: Event Correlation (EQL)",
 83    "Platform: Windows",
 84]
 85type = "eql"
 86
 87query = '''
 88sequence by process.entity_id
 89  [process where host.os.type == "windows" and (process.name : "Microsoft.Workflow.Compiler.exe" or
 90                  process.name : "bginfo.exe" or
 91                  process.name : "cdb.exe" or
 92                  process.name : "cmstp.exe" or
 93                  process.name : "csi.exe" or
 94                  process.name : "dnx.exe" or
 95                  process.name : "fsi.exe" or
 96                  process.name : "ieexec.exe" or
 97                  process.name : "iexpress.exe" or
 98                  process.name : "odbcconf.exe" or
 99                  process.name : "rcsi.exe" or
100                  process.name : "xwizard.exe") and
101     event.type == "start"]
102  [network where host.os.type == "windows" and (process.name : "Microsoft.Workflow.Compiler.exe" or
103                  process.name : "bginfo.exe" or
104                  process.name : "cdb.exe" or
105                  process.name : "cmstp.exe" or
106                  process.name : "csi.exe" or
107                  process.name : "dnx.exe" or
108                  process.name : "fsi.exe" or
109                  process.name : "ieexec.exe" or
110                  process.name : "iexpress.exe" or
111                  process.name : "odbcconf.exe" or
112                  process.name : "rcsi.exe" or
113                  process.name : "xwizard.exe")]
114'''
115
116
117[[rule.threat]]
118framework = "MITRE ATT&CK"
119
120[[rule.threat.technique]]
121id = "T1127"
122name = "Trusted Developer Utilities Proxy Execution"
123reference = "https://attack.mitre.org/techniques/T1127/"
124
125[[rule.threat.technique]]
126id = "T1218"
127name = "System Binary Proxy Execution"
128reference = "https://attack.mitre.org/techniques/T1218/"
129
130[[rule.threat.technique.subtechnique]]
131id = "T1218.003"
132name = "CMSTP"
133reference = "https://attack.mitre.org/techniques/T1218/003/"
134
135[[rule.threat.technique.subtechnique]]
136id = "T1218.008"
137name = "Odbcconf"
138reference = "https://attack.mitre.org/techniques/T1218/008/"
139
140[rule.threat.tactic]
141id = "TA0005"
142name = "Defense Evasion"
143reference = "https://attack.mitre.org/tactics/TA0005/"