AWS Credential Access RDS Password reset

Status: production
Severity: medium
Group by: aws::awsRegion, aws::recipientAccountId, aws::userAgent, dest, signature, src, user, vendor_product
Author: Gowthamaraj Rajendran, 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 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

Rule body splunk

name: AWS Credential Access RDS Password reset
id: 6153c5ea-ed30-4878-81e6-21ecdb198189
version: 13
creation_date: '2022-08-07'
modification_date: '2026-05-13'
author: Gowthamaraj Rajendran, 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 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:
    - AWS CloudTrail ModifyDBInstance
search: |-
    `cloudtrail` eventSource="rds.amazonaws.com" eventName=ModifyDBInstance "requestParameters.masterUserPassword"=*
      | rename user_name as user
      | stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.dBInstanceIdentifier) as database_id
        BY signature dest user
           user_agent src vendor_account
           vendor_region vendor_product
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `aws_credential_access_rds_password_reset_filter`
how_to_implement: You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs.
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  user = "$user$"'
      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: $database_id$ password has been reset from IP $src$
    entity:
        field: database_id
        type: system
        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/aws_cloudtrail_events.json
          source: aws_cloudtrail
          sourcetype: aws:cloudtrail
      test_type: unit

Stages and Predicates

Stage 1: `search`

`cloudtrail` eventSource="rds.amazonaws.com" eventName=ModifyDBInstance "requestParameters.masterUserPassword"=*

Stage 2: `rename`

| rename user_name as user

Stage 3: `stats`

| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.dBInstanceIdentifier) as database_id
    BY signature dest user
       user_agent src vendor_account
       vendor_region vendor_product

Stage 4: `search`

| `security_content_ctime(firstTime)`

Stage 5: `search`

| `security_content_ctime(lastTime)`

Stage 6: `search`

| `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
`"requestParameters.masterUserPassword"`	eq	`*`
`eventName`	eq	`ModifyDBInstance`
`eventSource`	eq	`"rds.amazonaws.com"`
`sourcetype`	eq	`aws:cloudtrail`

`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 Credential Access RDS Password reset

MITRE ATT&CK coverage

Rule body splunk

Stages and Predicates

Stage 1: `search`

Stage 2: `rename`

Stage 3: `stats`

Stage 4: `search`

Stage 5: `search`

Stage 6: `search`

Indicators

Keyboard shortcuts

Search operators

AWS Credential Access RDS Password reset

MITRE ATT&CK coverage

Rule body splunk

Stages and Predicates

Stage 1: search

Stage 2: rename

Stage 3: stats

Stage 4: search

Stage 5: search

Stage 6: search

Indicators

Stage 1: `search`

Stage 2: `rename`

Stage 3: `stats`

Stage 4: `search`

Stage 5: `search`

Stage 6: `search`