AWSCloudTrail - Privilege escalation via CRUD S3 policy

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Id	fc3061bb-319c-4fe9-abe2-f59899a6d907
Rulename	AWSCloudTrail - Privilege escalation via CRUD S3 policy
Description	Detects inline IAM policy updates that grant broad Amazon S3 create, read, update, and delete permissions. This type of policy expansion can be used to gain higher-impact access to cloud data and facilitate privilege escalation objectives.
Severity	Medium
Tactics	PrivilegeEscalation
Techniques	T1098.003
Required data connectors	AWS
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_PrivilegeEscalationViaCRUDS3Policy.yaml
Version	1.0.2
Arm template	fc3061bb-319c-4fe9-abe2-f59899a6d907.json

KQL

AWSCloudTrail
| where EventName in ("PutUserPolicy","PutRolePolicy","PutGroupPolicy") and isempty(ErrorCode) and isempty(ErrorMessage)
| 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 "s3:Create" and Action contains "s3:Get" and Action contains "s3:Put" and Action contains "s3:Delete") and Resource == "*" and Condition == ""
| 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]), "")
| distinct TimeGenerated, EventName, PolicyName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName

YAML

relevantTechniques:
- T1098.003
version: 1.0.2
severity: Medium
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_PrivilegeEscalationViaCRUDS3Policy.yaml
name: AWSCloudTrail - Privilege escalation via CRUD S3 policy
customDetails:
  EventName: EventName
  UserIdentityArn: UserIdentityArn
  RecipientAccountId: RecipientAccountId
  PolicyName: PolicyName
description: |
  Detects inline IAM policy updates that grant broad Amazon S3 create, read, update, and delete permissions.
  This type of policy expansion can be used to gain higher-impact access to cloud data and facilitate privilege
  escalation objectives.  
queryFrequency: 1d
tactics:
- PrivilegeEscalation
triggerThreshold: 0
queryPeriod: 1d
id: fc3061bb-319c-4fe9-abe2-f59899a6d907
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  - identifier: CloudAppAccountId
    columnName: RecipientAccountId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: SourceIpAddress
  entityType: IP
requiredDataConnectors:
- connectorId: AWS
  dataTypes:
  - AWSCloudTrail
triggerOperator: gt
alertDetailsOverride:
  alertDisplayNameFormat: AWS S3 privilege escalation policy update by {{AccountName}}
  alertDescriptionFormat: Detected {{EventName}} Event, updating inline S3 escalation policy {{PolicyName}} in account {{RecipientAccountId}}.
status: Available
query: |
  AWSCloudTrail
  | where EventName in ("PutUserPolicy","PutRolePolicy","PutGroupPolicy") and isempty(ErrorCode) and isempty(ErrorMessage)
  | 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 "s3:Create" and Action contains "s3:Get" and Action contains "s3:Put" and Action contains "s3:Delete") and Resource == "*" and Condition == ""
  | 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]), "")
  | distinct TimeGenerated, EventName, PolicyName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName  
kind: Scheduled

ARM