Detection rules › Kusto

AWSCloudTrail - Privilege escalation via CRUD IAM policy

Status
available
Severity
medium
Time window
1d
Source
github.com/Azure/Azure-Sentinel

Detects creation of inline IAM policies that grant broad IAM create, read, update, and delete capabilities. This behavior can establish or expand privileged control paths in the account and should be reviewed as potential privilege escalation.

MITRE ATT&CK coverage

TacticTechniques
Privilege EscalationT1098.003 Account Manipulation: Additional Cloud Roles

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Rule body kusto

id: e20d35a3-4fec-4c8b-81b1-fc33b41990b0
name: AWSCloudTrail - Privilege escalation via CRUD IAM policy
description: |
  Detects creation of inline IAM policies that grant broad IAM create, read, update, and delete capabilities.
  This behavior can establish or expand privileged control paths in the account and should be reviewed as potential
  privilege escalation.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: AWS
    dataTypes:
      - AWSCloudTrail
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - PrivilegeEscalation
relevantTechniques:
  - T1098.003
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 "iam:Create" and (Action contains "iam:Get" or Action contains "iam:List")  and Action contains "iam:Update" and Action contains "iam: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
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
  UserIdentityArn: UserIdentityArn
  RecipientAccountId: RecipientAccountId
alertDetailsOverride:
  alertDisplayNameFormat: 'AWS IAM privilege escalation policy update by {{AccountName}}'
  alertDescriptionFormat: 'Detected {{EventName}} Event, updating inline IAM escalation policy {{PolicyName}} in account {{RecipientAccountId}}.'
version: 1.0.2
kind: Scheduled

Stages and Predicates

Stage 1: source

AWSCloudTrail

Stage 2: where

| where EventName in ("PutUserPolicy","PutRolePolicy","PutGroupPolicy") and isempty(ErrorCode) and isempty(ErrorMessage)

Stage 3: extend

| extend PolicyName = tostring(parse_json(RequestParameters).policyName)

Stage 4: extend

| extend Statement = parse_json(tostring((parse_json(RequestParameters).policyDocument))).Statement

Stage 5: mv-expand

| mvexpand Statement

Stage 6: extend

| extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition)

Stage 7: extend

| extend Action = tostring(Action)

Stage 8: where

| where Effect =~ "Allow" and (Action contains "iam:Create" and (Action contains "iam:Get" or Action contains "iam:List")  and Action contains "iam:Update" and Action contains "iam:Delete") and Resource == "*" and Condition == ""

Stage 9: extend (4 consecutive steps)

| 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]), "")

Stage 10: distinct

| distinct TimeGenerated, EventName, PolicyName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Actioncontains
  • iam:Create
  • iam:Delete
  • iam:Get
  • iam:List
  • iam:Update
Effecteq
  • Allow
ErrorCodeis_null
  • (no value, null check)
ErrorMessageis_null
  • (no value, null check)
EventNamein
  • PutGroupPolicy transforms: cased
  • PutRolePolicy transforms: cased
  • PutUserPolicy transforms: cased
Resourceeq
  • * transforms: cased

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
PolicyNameextend
Statementextend
Actionextend
Conditionextend
Effectextend
Resourceextend
UserIdentityArnextend
UserNameextend
AccountNameextend
AccountUPNSuffixextend