AWS IAM User Not In Conflicting Groups

Severity: medium
Compliance: PCI 7.2.2
Tags: AWS, Configuration Required, Security, Identity & Compliance, PCI, Privilege Escalation:Valid Accounts
Reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_groups.html
Source: github.com/panther-labs/panther-analysis

This policy validates that IAM users are not in IAM groups that are considered mutually exclusive. For example, in some workflows developers are responsible for dev environments and sysadmins are responsible for prod environments. In this situation no (or very few) users should be in both sysadmin and developer groups. This is in following with the principle of least privilege.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1078` Valid Accounts

Rule body yaml

AnalysisType: policy
Filename: aws_iam_user_not_in_conflicting_groups.py
PolicyID: "AWS.IAM.User.NotInConflictingGroups"
DisplayName: "AWS IAM User Not In Conflicting Groups"
Enabled: false
ResourceTypes:
  - AWS.IAM.User
Tags:
  - AWS
  - Configuration Required
  - Security, Identity & Compliance
  - PCI
  - Privilege Escalation:Valid Accounts
Reports:
  PCI:
    - 7.2.2
  MITRE ATT&CK:
    - TA0004:T1078
Severity: Medium
Description: >
  This policy validates that IAM users are not in IAM groups that are considered mutually exclusive. For example, in some workflows developers are responsible for dev environments and sysadmins are responsible for prod environments. In this situation no (or very few) users should be in both sysadmin and developer groups. This is in following with the principle of least privilege.
Runbook: Remove the IAM user from one of the conflicting groups.
Reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_groups.html
Tests:
  - Name: User In Conflicting Groups
    ExpectedResult: false
    Resource:
      {
        "Arn": "arn:aws:iam::123456789012:user/Bobert",
        "CreateDate": "2019-05-10T21:49:56Z",
        "CredentialReport":
          {
            "ARN": "arn:aws:iam::123456789012:user/Bobert",
            "AccessKey1Active": true,
            "AccessKey1LastRotated": "2019-05-10T21:49:57Z",
            "AccessKey1LastUsedDate": "0001-01-01T00:00:00Z",
            "AccessKey1LastUsedRegion": "N/A",
            "AccessKey1LastUsedService": "N/A",
            "AccessKey2Active": false,
            "AccessKey2LastRotated": "0001-01-01T00:00:00Z",
            "AccessKey2LastUsedDate": "0001-01-01T00:00:00Z",
            "AccessKey2LastUsedRegion": "N/A",
            "AccessKey2LastUsedService": "N/A",
            "Cert1Active": false,
            "Cert1LastRotated": "0001-01-01T00:00:00Z",
            "Cert2Active": false,
            "Cert2LastRotated": "0001-01-01T00:00:00Z",
            "MfaActive": false,
            "PasswordEnabled": false,
            "PasswordLastChanged": "2019-05-21T22:10:11Z",
            "PasswordLastUsed": "0001-01-01T00:00:00Z",
            "PasswordNextRotation": "2019-08-14T22:10:11Z",
            "UserCreationTime": "2019-05-10T21:49:56Z",
            "UserName": "Bobert",
          },
        "Groups":
          [
            {
              "Arn": "arn:aws:iam::123456789012:group/ExampleGroup",
              "CreateDate": "2019-01-01T00:00:00Z",
              "GroupId": "ABCDEFGHIJKLMNOP",
              "GroupName": "PROD_ADMIN",
              "Path": "/",
            },
            {
              "Arn": "arn:aws:iam::123456789012:group/ExampleGroup",
              "CreateDate": "2019-01-01T00:00:00Z",
              "GroupId": "ABCDEFGHIJKLMNOP",
              "GroupName": "DEV",
              "Path": "/",
            },
          ],
        "InlinePolicyNames": null,
        "ManagedPolicyNames": ["IAMUserChangePassword"],
        "PasswordLastUsed": null,
        "Path": "/",
        "PermissionsBoundary": null,
        "Tags": null,
        "UserId": "ASDFASDFASDFASDF",
        "UserName": "Bobert",
        "VirtualMFA": null,
      }
  - Name: User Not In Conflicting Groups
    ExpectedResult: true
    Resource:
      {
        "Arn": "arn:aws:iam::123456789012:user/Bobert",
        "CreateDate": "2019-05-10T21:49:56Z",
        "CredentialReport":
          {
            "ARN": "arn:aws:iam::123456789012:user/Bobert",
            "AccessKey1Active": true,
            "AccessKey1LastRotated": "2019-05-10T21:49:57Z",
            "AccessKey1LastUsedDate": "0001-01-01T00:00:00Z",
            "AccessKey1LastUsedRegion": "N/A",
            "AccessKey1LastUsedService": "N/A",
            "AccessKey2Active": false,
            "AccessKey2LastRotated": "0001-01-01T00:00:00Z",
            "AccessKey2LastUsedDate": "0001-01-01T00:00:00Z",
            "AccessKey2LastUsedRegion": "N/A",
            "AccessKey2LastUsedService": "N/A",
            "Cert1Active": false,
            "Cert1LastRotated": "0001-01-01T00:00:00Z",
            "Cert2Active": false,
            "Cert2LastRotated": "0001-01-01T00:00:00Z",
            "MfaActive": true,
            "PasswordEnabled": true,
            "PasswordLastChanged": "2019-05-21T22:10:11Z",
            "PasswordLastUsed": "0001-01-01T00:00:00Z",
            "PasswordNextRotation": "2019-08-14T22:10:11Z",
            "UserCreationTime": "2019-05-10T21:49:56Z",
            "UserName": "Bobert",
          },
        "Groups":
          [
            {
              "Arn": "arn:aws:iam::123456789012:group/ExampleGroup",
              "CreateDate": "2019-01-01T00:00:00Z",
              "GroupId": "ABCDEFGHIJKLMNOP",
              "GroupName": "ExampleGroup",
              "Path": "/",
            },
          ],
        "InlinePolicyNames": null,
        "ManagedPolicyNames": ["IAMUserChangePassword"],
        "PasswordLastUsed": null,
        "Path": "/",
        "PermissionsBoundary": null,
        "Tags": null,
        "UserId": "ASDFASDFASDFASDF",
        "UserName": "Bobert",
        "VirtualMFA": null,
      }

Detection logic

Rule logic imperative Python

GROUP_CONFLICTS = [
    {"PROD_ADMIN", "DEV"},
]
def policy(resource):
    group_names = {group["GroupName"] for group in resource["Groups"] or []}
    for conflict_set in GROUP_CONFLICTS:
        if len(group_names.intersection(conflict_set)) > 1:
            return False
    return True

The parser cannot express this rule's logic as a field filter; the imperative Python above is the detection.

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`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)

AWS IAM User Not In Conflicting Groups

MITRE ATT&CK coverage

Rule body yaml

Detection logic

Rule logic imperative Python

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