IAM Policy Modified

Severity: informational
Group by: recipientAccountId
Compliance: CIS 3.4; Stratus Red Team aws.persistence.iam-create-admin-user, aws.persistence.iam-create-backdoor-role
Log types: AWS.CloudTrail
Tags: AWS, Identity & Access Management, Privilege Escalation:Abuse Elevation Control Mechanism
Reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html
Source: github.com/panther-labs/panther-analysis

An IAM Policy was changed.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1548` Abuse Elevation Control Mechanism

Rules detecting the same action

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

ASL AWS Create Policy Version to allow all resources (Splunk)
ASL AWS IAM Delete Policy (Splunk)
AWS IAM Access Key Compromise Detection (Panther)
AWS IAM CompromisedKeyQuarantine Policy Attached to User (Elastic)
AWS IAM Delete Policy (Splunk)
AWS Lateral Movement from Kubernetes SA via AssumeRoleWithWebIdentity (Elastic)
AWSCloudTrail - CloudFormation policy created then used for privilege escalation (Kusto)
AWSCloudTrail - Created CRUD S3 policy and then privilege escalation (Kusto)

Rule body yaml

AnalysisType: rule
Filename: aws_iam_policy_modified.py
RuleID: "AWS.IAM.PolicyModified"
DisplayName: "IAM Policy Modified"
Enabled: true
LogTypes:
  - AWS.CloudTrail
Tags:
  - AWS
  - Identity & Access Management
  - Privilege Escalation:Abuse Elevation Control Mechanism
Reports:
  CIS:
    - 3.4
  MITRE ATT&CK:
    - TA0004:T1548

  Stratus Red Team:
    - aws.persistence.iam-create-admin-user
    - aws.persistence.iam-create-backdoor-role
Severity: Info
DedupPeriodMinutes: 720 # 12 hours
Description: >
  An IAM Policy was changed.
Runbook: https://docs.runpanther.io/alert-runbooks/built-in-rules/aws-iam-policy-modified
Reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html
SummaryAttributes:
  - eventName
  - userAgent
  - sourceIpAddress
  - recipientAccountId
  - p_any_aws_arns
Tests:
  - Name: IAM Policy Change
    ExpectedResult: true
    Log:
      {
        "eventVersion": "1.05",
        "userIdentity":
          {
            "type": "AssumedRole",
            "principalId": "1111:tester",
            "arn": "arn:aws:sts::123456789012:assumed-role/tester",
            "accountId": "123456789012",
            "accessKeyId": "1",
            "sessionContext":
              {
                "attributes":
                  {
                    "mfaAuthenticated": "true",
                    "creationDate": "2019-01-01T00:00:00Z",
                  },
                "sessionIssuer":
                  {
                    "type": "Role",
                    "principalId": "1111",
                    "arn": "arn:aws:iam::123456789012:role/tester",
                    "accountId": "123456789012",
                    "userName": "tester",
                  },
              },
          },
        "eventTime": "2019-01-01T00:00:00Z",
        "eventSource": "iam.amazonaws.com",
        "eventName": "DeleteGroupPolicy",
        "awsRegion": "us-east-1",
        "sourceIPAddress": "111.111.111.111",
        "userAgent": "console.amazonaws.com",
        "requestParameters": { "policyName": "policy", "groupName": "group" },
        "responseElements": null,
        "requestID": "1",
        "eventID": "1",
        "eventType": "AwsApiCall",
        "recipientAccountId": "123456789012",
      }
  - Name: Not IAM Policy Change
    ExpectedResult: false
    Log:
      {
        "eventVersion": "1.06",
        "userIdentity":
          {
            "type": "AssumedRole",
            "principalId": "1111:tester",
            "arn": "arn:aws:sts::123456789012:assumed-role/tester",
            "accountId": "123456789012",
            "accessKeyId": "1",
            "sessionContext":
              {
                "sessionIssuer":
                  {
                    "type": "Role",
                    "principalId": "1111",
                    "arn": "arn:aws:iam::123456789012:role/tester",
                    "accountId": "123456789012",
                    "userName": "tester",
                  },
                "attributes":
                  {
                    "creationDate": "2019-01-01T00:00:00Z",
                    "mfaAuthenticated": "true",
                  },
              },
          },
        "eventTime": "2019-01-01T00:00:00Z",
        "eventSource": "dynamodb.amazonaws.com",
        "eventName": "DescribeTable",
        "awsRegion": "us-west-2",
        "sourceIPAddress": "111.111.111.111",
        "userAgent": "console.amazonaws.com",
        "requestParameters": { "tableName": "table" },
        "responseElements": null,
        "requestID": "1",
        "eventID": "1",
        "readOnly": true,
        "resources":
          [
            {
              "accountId": "123456789012",
              "type": "AWS::DynamoDB::Table",
              "ARN": "arn:aws:dynamodb:us-west-2:123456789012:table/table",
            },
          ],
        "eventType": "AwsApiCall",
        "apiVersion": "2012-08-10",
        "managementEvent": true,
        "recipientAccountId": "123456789012",
      }
  - Name: IAM Policy Change Error
    ExpectedResult: false
    Log:
      {
        "eventVersion": "1.05",
        "errorCode": "NoSuchEntity",
        "userIdentity":
          {
            "type": "AssumedRole",
            "principalId": "1111:tester",
            "arn": "arn:aws:sts::123456789012:assumed-role/tester",
            "accountId": "123456789012",
            "accessKeyId": "1",
            "sessionContext":
              {
                "attributes":
                  {
                    "mfaAuthenticated": "true",
                    "creationDate": "2019-01-01T00:00:00Z",
                  },
                "sessionIssuer":
                  {
                    "type": "Role",
                    "principalId": "1111",
                    "arn": "arn:aws:iam::123456789012:role/tester",
                    "accountId": "123456789012",
                    "userName": "tester",
                  },
              },
          },
        "eventTime": "2019-01-01T00:00:00Z",
        "eventSource": "iam.amazonaws.com",
        "eventName": "DeleteGroupPolicy",
        "awsRegion": "us-east-1",
        "sourceIPAddress": "111.111.111.111",
        "userAgent": "console.amazonaws.com",
        "requestParameters": { "policyName": "policy", "groupName": "group" },
        "responseElements": null,
        "requestID": "1",
        "eventID": "1",
        "eventType": "AwsApiCall",
        "recipientAccountId": "123456789012",
      }

Detection logic

Condition

not (errorCode is_not_null or errorMessage is_not_null)
eventName in ["DeleteGroupPolicy", "DeleteRolePolicy", "DeleteUserPolicy", "PutGroupPolicy", "PutRolePolicy", "PutUserPolicy", "CreatePolicy", "DeletePolicy", "CreatePolicyVersion", "DeletePolicyVersion", "AttachRolePolicy", "DetachRolePolicy", "AttachUserPolicy", "DetachUserPolicy", "AttachGroupPolicy", "DetachGroupPolicy"]

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`errorCode`	is_not_null	(no value, null check)
`errorMessage`	is_not_null	(no value, null check)

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.

Field	Kind	Values
`eventName`	in	`AttachGroupPolicy` `AttachRolePolicy` `AttachUserPolicy` `CreatePolicy` `CreatePolicyVersion` `DeleteGroupPolicy` `DeletePolicy` `DeletePolicyVersion` `DeleteRolePolicy` `DeleteUserPolicy` `DetachGroupPolicy` `DetachRolePolicy` `DetachUserPolicy` `PutGroupPolicy` `PutRolePolicy` `PutUserPolicy`

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.

Field
`eventName`
`eventSource`
`awsRegion`
`recipientAccountId`
`sourceIPAddress`
`userAgent`
`userIdentity`

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`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)