ASL AWS Credential Access RDS Password reset

Status: production
Severity: medium
Group by: "actor.user.account.uid", "actor.user.uid", "api.operation", "api.request.data", "api.service.name", "cloud.provider", "cloud.region", "http_request.user_agent", "src_endpoint.ip"
Author: Patrick Bareiss, Splunk
Source: github.com/splunk/security_content

The following analytic detects the resetting of the master user password for an Amazon RDS DB instance. It leverages AWS CloudTrail logs from Amazon Security Lake to identify events where the ModifyDBInstance API call includes a new masterUserPassword parameter. This activity is significant because unauthorized password resets can grant attackers access to sensitive data stored in production databases, such as credit card information, PII, and healthcare data. If confirmed malicious, this could lead to data breaches, regulatory non-compliance, and significant reputational damage. Immediate investigation is required to determine the legitimacy of the password reset.

MITRE ATT&CK coverage

Tactic	Techniques
Resource Development	`T1586.003` Compromise Accounts: Cloud Accounts
Credential Access	`T1110` Brute Force

Rules detecting the same action

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

AWSCloudTrail - RDS instance publicly exposed (Kusto)

Rule body splunk

name: ASL AWS Credential Access RDS Password reset
id: d15e9bd9-ef64-4d84-bc04-f62955a9fee8
version: 9
creation_date: '2022-08-07'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic detects the resetting of the master user password for an Amazon RDS DB instance. It leverages AWS CloudTrail logs from Amazon Security Lake to identify events where the `ModifyDBInstance` API call includes a new `masterUserPassword` parameter. This activity is significant because unauthorized password resets can grant attackers access to sensitive data stored in production databases, such as credit card information, PII, and healthcare data. If confirmed malicious, this could lead to data breaches, regulatory non-compliance, and significant reputational damage. Immediate investigation is required to determine the legitimacy of the password reset.
data_source:
    - ASL AWS CloudTrail
search: |-
    `amazon_security_lake` api.operation=ModifyDBInstance OR api.operation=ModifyDBCluster
      | spath input=api.request.data
      | search masterUserPassword=*
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY actor.user.uid api.operation api.service.name
           http_request.user_agent src_endpoint.ip actor.user.account.uid
           cloud.provider cloud.region api.request.data
      | rename actor.user.uid as user api.operation as action api.service.name as dest http_request.user_agent as user_agent src_endpoint.ip as src actor.user.account.uid as vendor_account cloud.provider as vendor_product cloud.region as vendor_region
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `asl_aws_credential_access_rds_password_reset_filter`
how_to_implement: The detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App.
known_false_positives: Users may genuinely reset the RDS password.
references:
    - https://aws.amazon.com/premiumsupport/knowledge-center/reset-master-user-password-rds
drilldown_searches:
    - name: View the detection results for - "$user$"
      search: '%original_detection_search% | search  database_id = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: User $user$ is seen to reset the password for database
    entity:
        field: user
        type: user
        score: 50
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - AWS Identity and Access Management Account Takeover
    - Scattered Lapsus$ Hunters
asset_type: AWS Account
mitre_attack_id:
    - T1110
    - T1586.003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1110.002/aws_rds_password_reset/asl_ocsf_cloudtrail.json
          sourcetype: aws:asl
          source: aws_asl
      test_type: unit

Stages and Predicates

Stage 1: `search`

`amazon_security_lake` api.operation=ModifyDBInstance OR api.operation=ModifyDBCluster

Stage 2: `spath`

| spath input=api.request.data

Stage 3: `search`

| search masterUserPassword=*

Stage 4: `fillnull`

| fillnull

Stage 5: `stats`

| stats count min(_time) as firstTime max(_time) as lastTime
    BY actor.user.uid api.operation api.service.name
       http_request.user_agent src_endpoint.ip actor.user.account.uid
       cloud.provider cloud.region api.request.data

Stage 6: `rename`

| rename actor.user.uid as user api.operation as action api.service.name as dest http_request.user_agent as user_agent src_endpoint.ip as src actor.user.account.uid as vendor_account cloud.provider as vendor_product cloud.region as vendor_region

Stage 7: `search`

| `security_content_ctime(firstTime)`

Stage 8: `search`

| `security_content_ctime(lastTime)`

Stage 9: `search`

| `asl_aws_credential_access_rds_password_reset_filter`

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
`api.operation`	eq	`ModifyDBCluster` `ModifyDBInstance`
`masterUserPassword`	eq	`*`
`sourcetype`	eq	`aws:asl`

`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)

ASL AWS Credential Access RDS Password reset

MITRE ATT&CK coverage

Rules detecting the same action

Rule body splunk

Stages and Predicates

Stage 1: `search`

Stage 2: `spath`

Stage 3: `search`

Stage 4: `fillnull`

Stage 5: `stats`

Stage 6: `rename`

Stage 7: `search`

Stage 8: `search`

Stage 9: `search`

Indicators

Keyboard shortcuts

Search operators

ASL AWS Credential Access RDS Password reset

MITRE ATT&CK coverage

Rules detecting the same action

Rule body splunk

Stages and Predicates

Stage 1: search

Stage 2: spath

Stage 3: search

Stage 4: fillnull

Stage 5: stats

Stage 6: rename

Stage 7: search

Stage 8: search

Stage 9: search

Indicators

Stage 1: `search`

Stage 2: `spath`

Stage 3: `search`

Stage 4: `fillnull`

Stage 5: `stats`

Stage 6: `rename`

Stage 7: `search`

Stage 8: `search`

Stage 9: `search`