AWSCloudTrail - CloudFormation policy created then used for privilege escalation

id: efdc3cff-f006-426f-97fd-4657862f7b9a
name: AWSCloudTrail - CloudFormation policy created then used for privilege escalation
description: |
  Identifies creation of IAM policies that grant CloudFormation and IAM permissions commonly used for privilege
  escalation, followed by attachment activity to a user, role, or group. Review whether the new policy and any
  subsequent attachment were authorized because this pattern can enable an attacker to create or elevate access.
severity: High
status: Available
requiredDataConnectors:
  - connectorId: AWS
    dataTypes:
      - AWSCloudTrail
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - DefenseEvasion
  - PrivilegeEscalation
  - Persistence
relevantTechniques:
  - T1484
  - T1098.003
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 has "iam:*" or Action has "iam:PassRole") and Action has "cloudformation:*") or ((Action has "iam:*" or Action has "iam:PassRole") and Action contains "cloudformation:DescribeStacks" and Action contains "cloudformation:CreateStack") or ((Action contains "iam:*" or Action contains "iam:PassRole") and Action contains "cloudformation:Describe*" and Action contains "cloudformation:Create*")) 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,   RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityType , UserIdentityArn, SourceIpAddress, 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, AttachEventCount, RecipientAccountId, AccountName, AccountUPNSuffix
  );
  // 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
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
      - identifier: CloudAppAccountId
        columnName: RecipientAccountId
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIpAddress
customDetails:
  PolicyName: PolicyName
  EventName: EventName
  RecipientAccountId: RecipientAccountId
  UserIdentityArn: UserIdentityArn
alertDetailsOverride:
  alertDisplayNameFormat: 'AWS CloudFormation privilege escalation policy activity: {{PolicyName}} by {{AccountName}}'
  alertDescriptionFormat: 'Detected {{EventName}} for policy {{PolicyName}} from {{SourceIpAddress}}.'
version: 1.0.4
kind: Scheduled