AWSCloudTrail
| where EventName in~ ("ModifyInstanceAttribute", "CreateLaunchTemplate")
| extend RequestParametersJson = parse_json(RequestParameters)
| where tostring(RequestParametersJson.userData) != ""
| extend userData_ = tostring(RequestParametersJson.userData)
| extend instanceId_ = tostring(RequestParametersJson.instanceId)
| project-away SourceSystem, Category, Type, TenantId, EventVersion, SessionIssuerAccountId
| extend UserName = substring(UserIdentityPrincipalid, indexof_regex(UserIdentityPrincipalid, ":") + 1)
| extend Name = split(UserName,'@')[0],UpnSuffix = split(UserName,'@')[1]
| project TimeGenerated, EventName, UserName, Name, UpnSuffix, instanceId_, AWSRegion, SourceIpAddress, EventSource, UserIdentityArn, EventTypeName
status: Available
queryFrequency: 15m
queryPeriod: 15m
triggerOperator: gt
query: |
AWSCloudTrail
| where EventName in~ ("ModifyInstanceAttribute", "CreateLaunchTemplate")
| extend RequestParametersJson = parse_json(RequestParameters)
| where tostring(RequestParametersJson.userData) != ""
| extend userData_ = tostring(RequestParametersJson.userData)
| extend instanceId_ = tostring(RequestParametersJson.instanceId)
| project-away SourceSystem, Category, Type, TenantId, EventVersion, SessionIssuerAccountId
| extend UserName = substring(UserIdentityPrincipalid, indexof_regex(UserIdentityPrincipalid, ":") + 1)
| extend Name = split(UserName,'@')[0],UpnSuffix = split(UserName,'@')[1]
| project TimeGenerated, EventName, UserName, Name, UpnSuffix, instanceId_, AWSRegion, SourceIpAddress, EventSource, UserIdentityArn, EventTypeName
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_EC2StartupShellScriptChanged.yaml
tactics:
- Execution
triggerThreshold: 0
entityMappings:
- entityType: Account
fieldMappings:
- identifier: Name
columnName: Name
- identifier: UPNSuffix
columnName: UpnSuffix
- entityType: IP
fieldMappings:
- identifier: Address
columnName: SourceIpAddress
requiredDataConnectors:
- connectorId: AWS
dataTypes:
- AWSCloudTrail
alertDetailsOverride:
alertDescriptionFormat: EC2 startup script changed on {{instanceId_}} by {{UserName}} in {{AWSRegion}}.
alertDisplayNameFormat: EC2 startup script changed on {{instanceId_}} by {{UserName}}
relevantTechniques:
- T1059
customDetails:
EventSource: EventSource
EventType: EventTypeName
EventName: EventName
InstanceId: instanceId_
AWSRegion: AWSRegion
description: |
Identifies changes to the EC2 startup script. The shell script will be executed as root/SYSTEM every time the specific instances are booted up. ref : https://github.com/RhinoSecurityLabs/pacu/blob/master/pacu/modules/ec2__startup_shell_script/main.py
name: AWSCloudTrail - EC2 Startup Shell Script Changed
version: 1.0.1
kind: Scheduled
id: f8577e4d-8481-437b-a94e-06f615985668
severity: Medium
