AWSCloudTrail - Creation of CRUD Lambda policy and then privilege escalation

let EventNameList = dynamic(["AttachUserPolicy","AttachRolePolicy","AttachGroupPolicy"]);
let createPolicy =  dynamic(["CreatePolicy", "CreatePolicyVersion"]);
let timeframe = 1d;
let lookback = 14d;
// Creating Master table with all the events to use with materialize for better performance
let EventInfo = AWSCloudTrail
| where TimeGenerated >= ago(lookback)
| where EventName in (EventNameList) or EventName in (createPolicy)
| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
| extend UserName = tostring(split(UserIdentityArn, '/')[-1])
| extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
| extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
  AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "");
//Checking for Policy creation event with Full Admin Privileges since lookback period.
let FullAdminPolicyEvents =  materialize(  EventInfo
| where TimeGenerated >= ago(lookback)
| where EventName in (createPolicy)
| extend PolicyName = tostring(parse_json(RequestParameters).policyName)
| extend Statement = parse_json(tostring((parse_json(RequestParameters).policyDocument))).Statement
| mvexpand Statement
| extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition)
| extend Action = tostring(Action)
| where Effect =~ "Allow" and (Action contains "lambda:Create" and Action contains "lambda:Get" and Action contains "lambda:Update" and Action contains "lambda:Delete") and Resource == "*" and Condition == ""
| distinct TimeGenerated, EventName, PolicyName, SourceIpAddress, UserIdentityArn, RecipientAccountId, AccountName, AccountUPNSuffix
| project-rename StartTime = TimeGenerated  );
let PolicyAttach = materialize(EventInfo
| where TimeGenerated >= ago(timeframe)
| where EventName in (EventNameList) and isempty(ErrorCode) and isempty(ErrorMessage)
| extend PolicyName = tostring(split(tostring(parse_json(RequestParameters).policyArn),"/")[1])
| summarize AttachEventCount=count(), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventSource, EventName, UserIdentityType , UserIdentityArn, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, PolicyName
| extend AttachEvent = pack("StartTime", StartTime, "EndTime", EndTime, "EventName", EventName, "UserIdentityType",   UserIdentityType, "SourceIpAddress", SourceIpAddress, "AccountName", AccountName, "AccountUPNSuffix", AccountUPNSuffix, "RecipientAccountId", RecipientAccountId, "UserIdentityArn", UserIdentityArn)
| project EventSource, PolicyName, AttachEvent, RecipientAccountId, AccountName, AccountUPNSuffix, AttachEventCount
);
// Joining the list of PolicyNames and checking if it has been attached to any Roles/Users/Groups.
// These Roles/Users/Groups will be Privileged and can be used by adversaries as pivot point for privilege escalation via multiple ways.
FullAdminPolicyEvents
| join kind=leftouter
(
    PolicyAttach
)
on PolicyName
| project-away PolicyName1

status: Available
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
query: |
  let EventNameList = dynamic(["AttachUserPolicy","AttachRolePolicy","AttachGroupPolicy"]);
  let createPolicy =  dynamic(["CreatePolicy", "CreatePolicyVersion"]);
  let timeframe = 1d;
  let lookback = 14d;
  // Creating Master table with all the events to use with materialize for better performance
  let EventInfo = AWSCloudTrail
  | where TimeGenerated >= ago(lookback)
  | where EventName in (EventNameList) or EventName in (createPolicy)
  | extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
  | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
  | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
  | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
    AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "");
  //Checking for Policy creation event with Full Admin Privileges since lookback period.
  let FullAdminPolicyEvents =  materialize(  EventInfo
  | where TimeGenerated >= ago(lookback)
  | where EventName in (createPolicy)
  | extend PolicyName = tostring(parse_json(RequestParameters).policyName)
  | extend Statement = parse_json(tostring((parse_json(RequestParameters).policyDocument))).Statement
  | mvexpand Statement
  | extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition)
  | extend Action = tostring(Action)
  | where Effect =~ "Allow" and (Action contains "lambda:Create" and Action contains "lambda:Get" and Action contains "lambda:Update" and Action contains "lambda:Delete") and Resource == "*" and Condition == ""
  | distinct TimeGenerated, EventName, PolicyName, SourceIpAddress, UserIdentityArn, RecipientAccountId, AccountName, AccountUPNSuffix
  | project-rename StartTime = TimeGenerated  );
  let PolicyAttach = materialize(EventInfo
  | where TimeGenerated >= ago(timeframe)
  | where EventName in (EventNameList) and isempty(ErrorCode) and isempty(ErrorMessage)
  | extend PolicyName = tostring(split(tostring(parse_json(RequestParameters).policyArn),"/")[1])
  | summarize AttachEventCount=count(), StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventSource, EventName, UserIdentityType , UserIdentityArn, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, PolicyName
  | extend AttachEvent = pack("StartTime", StartTime, "EndTime", EndTime, "EventName", EventName, "UserIdentityType",   UserIdentityType, "SourceIpAddress", SourceIpAddress, "AccountName", AccountName, "AccountUPNSuffix", AccountUPNSuffix, "RecipientAccountId", RecipientAccountId, "UserIdentityArn", UserIdentityArn)
  | project EventSource, PolicyName, AttachEvent, RecipientAccountId, AccountName, AccountUPNSuffix, AttachEventCount
  );
  // Joining the list of PolicyNames and checking if it has been attached to any Roles/Users/Groups.
  // These Roles/Users/Groups will be Privileged and can be used by adversaries as pivot point for privilege escalation via multiple ways.
  FullAdminPolicyEvents
  | join kind=leftouter
  (
      PolicyAttach
  )
  on PolicyName
  | project-away PolicyName1  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_CreatedCRUDLambdaPolicytoPrivilegEscalation.yaml
tactics:
- DefenseEvasion
- PrivilegeEscalation
- Persistence
triggerThreshold: 0
entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  - identifier: CloudAppAccountId
    columnName: RecipientAccountId
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: SourceIpAddress
requiredDataConnectors:
- connectorId: AWS
  dataTypes:
  - AWSCloudTrail
alertDetailsOverride:
  alertDescriptionFormat: Detected {{EventName}} for policy {{PolicyName}} in account {{RecipientAccountId}}.
  alertDisplayNameFormat: 'AWS Lambda privilege escalation policy activity: {{PolicyName}} by {{AccountName}}'
relevantTechniques:
- T1484
- T1098.003
customDetails:
  RecipientAccountId: RecipientAccountId
  EventName: EventName
  PolicyName: PolicyName
  UserIdentityArn: UserIdentityArn
description: |
  Identifies creation of IAM policies that grant broad AWS Lambda CRUD permissions and subsequent policy attachment
  activity to a principal. This behavior may indicate an attempt to add capabilities that support privilege
  escalation or unauthorized execution pathways.  
name: AWSCloudTrail - Creation of CRUD Lambda policy and then privilege escalation
version: 1.0.4
kind: Scheduled
id: 22115d3c-e87c-485a-9130-33797d619124
severity: Medium