AWS STS GetSessionToken Misuse

Status: test
Severity: low
Log source: product aws, service cloudtrail
Author: Austin Songer @austinsonger
Source: github.com/SigmaHQ/sigma

Identifies the suspicious use of GetSessionToken. Tokens could be created and used by attackers to move laterally and escalate privileges.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1548` Abuse Elevation Control Mechanism
Lateral Movement	`T1550.001` Use Alternate Authentication Material: Application Access Token

Event coverage

Provider	Event
AWS-sts	GetSessionToken

Rules detecting the same action

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

AWS Authentication from CrowdStrike Unmanaged Device (crowdstrike_fdrevent table) (Panther)
AWS STS GetSessionToken by IAM User (Panther)
AWS STS GetSessionToken Usage (Elastic)

Rule body yaml

title: AWS STS GetSessionToken Misuse
id: b45ab1d2-712f-4f01-a751-df3826969807
status: test
description: Identifies the suspicious use of GetSessionToken. Tokens could be created and used by attackers to move laterally and escalate privileges.
references:
    - https://github.com/elastic/detection-rules/pull/1213
    - https://docs.aws.amazon.com/STS/latest/APIReference/API_GetSessionToken.html
author: Austin Songer @austinsonger
date: 2021-07-24
modified: 2022-10-09
tags:
    - attack.lateral-movement
    - attack.privilege-escalation
    - attack.t1548
    - attack.t1550
    - attack.t1550.001
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        eventSource: sts.amazonaws.com
        eventName: GetSessionToken
        userIdentity.type: IAMUser
    condition: selection
falsepositives:
    - GetSessionToken may be done by a system or network administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment. GetSessionToken from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: low

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    eventSource: sts.amazonaws.com
    eventName: GetSessionToken
    userIdentity.type: IAMUser

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	`GetSessionToken`
`eventSource`	eq	`sts.amazonaws.com`
`userIdentity.type`	eq	`IAMUser`

`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 STS GetSessionToken Misuse

MITRE ATT&CK coverage

Event coverage

Rules detecting the same action

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

AWS STS GetSessionToken Misuse

MITRE ATT&CK coverage

Event coverage

Rules detecting the same action

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`