AWS SSM Multiple Sessions

Severity: informational
Tags: AWS CloudTrail, AWS SSM, Execution: Exploitation for Client Execution, Beta
Reference: https://stratus-red-team.cloud/attack-techniques/AWS/aws.execution.ssm-start-session/
Source: github.com/panther-labs/panther-analysis

Detect when an actor launches multiple distinct SSM sessions within a single hour period.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1203` Exploitation for Client Execution

Rule body yaml

AnalysisType: scheduled_rule
Filename: aws_ssm_multiple_sessions.py
RuleID: "AWS.SSM.MultipleSessions"
DisplayName: "AWS SSM Multiple Sessions"
Enabled: true
ScheduledQueries:
  - AWS SSM Multiple Sessions
Severity: Info
Reports:
  MITRE ATT&CK:
    - TA0002:T1203 # Execution: Exploitation for Client Execution
Description: >
  Detect when an actor launches multiple distinct SSM sessions within a single hour period.
Reference: >
  https://stratus-red-team.cloud/attack-techniques/AWS/aws.execution.ssm-start-session/
Runbook:
  Identify the instances for which sessions were started. Monitor instance and session activity. If possible, reach out to the user to determine the reason for multiple sessions.
SummaryAttributes:
  - requestParameters.target
Tags:
    - AWS CloudTrail
    - AWS SSM
    - 'Execution: Exploitation for Client Execution'
    - Beta
Tests:
  - Name: Sample Result
    ExpectedResult: true
    Log:
      {
        "p_event_time": "2025-02-19 20:13:49",
        "p_log_type": "AWS.CloudTrail",
        "p_parse_time": "2025-02-19 20:15:54.4",
        "awsRegion": "us-west-2",
        "eventCategory": "Management",
        "eventID": "c61c9a5d-4d9c-45ee-8c46-9845ea001e97",
        "eventName": "StartSession",
        "eventSource": "ssm.amazonaws.com",
        "eventTime": "2025-02-19 20:13:49",
        "eventType": "AwsApiCall",
        "eventVersion": "1.10",
        "managementEvent": true,
        "readOnly": false,
        "recipientAccountId": "111122223333",
        "requestID": "8e6cef5f-2610-43fb-898b-48acd3aa6240",
        "requestParameters": {
          "target": "i-047fce8bf4806e5ee"
        },
        "responseElements": {
          "sessionId": "bobson.dugnutt-4njnyxxl8yn676nsla8j6l4bra",
          "tokenValue": "Value hidden due to security reasons."
        },
        "sourceIPAddress": "1.2.3.4",
        "tlsDetails": {
          "cipherSuite": "ECDHE-RSA-AES128-GCM-SHA256",
          "clientProvidedHostHeader": "ssm.us-west-2.amazonaws.com",
          "tlsVersion": "TLSv1.2"
        },
        "userAgent": "sample-user-agent",
        "userIdentity": {
          "accessKeyId": "SAMPLE_ACCESS_KEY_ID",
          "accountId": "111122223333",
          "arn": "arn:aws:sts::111122223333:assumed-role/SampleRole/bobson.dugnutt",
          "principalId": "SAMPLE_PRINCIPAL_ID:bobson.dugnutt",
          "sessionContext": {
            "attributes": {
              "creationDate": "2025-02-19T16:29:24Z",
              "mfaAuthenticated": "false"
            },
            "sessionIssuer": {
              "accountId": "111122223333",
              "arn": "arn:aws:iam::111122223333:role/aws-reserved/sso.amazonaws.com/us-west-2/SampleRole",
              "principalId": "SAMPLE_PRINCIPAL_ID",
              "type": "Role",
              "userName": "SampleRole"
            }
          },
          "type": "AssumedRole"
        }
      }

Detection logic

Filter

from panther_aws_helpers import aws_rule_context, get_actor_user
from panther_core import PantherEvent


def rule(_) -> bool:
    return True


def title(event: PantherEvent) -> str:
    actor = get_actor_user(event)
    aws_account = event.get("recipientAccountId")
    return f"Multiple SSM Sessions Started by {actor} in {aws_account}"


def alert_context(event: PantherEvent) -> dict:
    return aws_rule_context(event)

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`

`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)