SIGNAL - Role Assumed by AWS Service

Severity: informational
Log types: AWS.CloudTrail
Source: github.com/panther-labs/panther-analysis

Rules detecting the same action

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

AWS Potentially Stolen Service Role (Panther)
SIGNAL - Role Assumed by User (Panther)

Rule body yaml

AnalysisType: rule
Filename: role_assumed_by_aws_service.py
RuleID: "Role.Assumed.by.AWS.Service"
DisplayName: "SIGNAL - Role Assumed by AWS Service"
Enabled: false
CreateAlert: false
LogTypes:
    - AWS.CloudTrail
Severity: Info
DedupPeriodMinutes: 60
Threshold: 1
Tests:
    - Name: Role Assumed by AWS Service
      ExpectedResult: true
      Log:
        awsRegion: us-west-2
        eventCategory: Management
        eventID: 1f3d7d49-6637-3304-b959-9be15f20215d
        eventName: AssumeRole
        eventSource: sts.amazonaws.com
        eventTime: "2024-06-02 20:27:12"
        eventType: AwsApiCall
        eventVersion: "1.08"
        managementEvent: true
        readOnly: true
        recipientAccountId: "123456789123"
        requestID: a0dda101-6e27-4f88-8250-f3d475f88b56
        requestParameters:
            roleArn: arn:aws:iam::123456789123:role/my_role_arn
            roleSessionName: awslambda_55_20240602202712548
        resources:
            - accountId: "123456789123"
              arn: arn:aws:iam::123456789123:role/my_role_arn
              type: AWS::IAM::Role
        responseElements:
            credentials:
                accessKeyId: REDACTED
                expiration: Jun 2, 2024, 10:37:12 PM
                sessionToken: REDACTED
        sharedEventID: 95e84e79-100a-40a6-985e-3c9c4b41f622
        sourceIPAddress: lambda.amazonaws.com
        userAgent: lambda.amazonaws.com
        userIdentity:
            invokedBy: lambda.amazonaws.com
            type: AWSService

Detection logic

Condition

eventName eq "AssumeRole"
requestParameters.roleArn is_not_null
userIdentity.type eq "AWSService"

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`	eq	`AssumeRole`
`requestParameters.roleArn`	is_not_null	(no value, null check)
`userIdentity.type`	eq	`AWSService`

`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)