AWS RDS Snapshot Copied Cross-Region

Severity: medium
Group by: awsRegion, recipientAccountId, requestParameters.targetDBSnapshotIdentifier
Log types: AWS.CloudTrail
Tags: AWS, Exfiltration, Transfer Data to Cloud Account, RDS
Reference: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_CopySnapshot.html
Source: github.com/panther-labs/panther-analysis

Detects when RDS snapshots are copied to different AWS regions. While legitimate for disaster recovery, cross-region snapshot copies can be used for data exfiltration or to prepare snapshots for sharing with external accounts.

MITRE ATT&CK coverage

Tactic	Techniques
Exfiltration	`T1537` Transfer Data to Cloud Account

Rule body yaml

AnalysisType: rule
Filename: aws_rds_snapshot_copied_cross_region.py
RuleID: "AWS.RDS.SnapshotCopiedCrossRegion"
DisplayName: "AWS RDS Snapshot Copied Cross-Region"
Enabled: true
LogTypes:
  - AWS.CloudTrail
Tags:
  - AWS
  - Exfiltration
  - Transfer Data to Cloud Account
  - RDS
Severity: Medium
Description: >
  Detects when RDS snapshots are copied to different AWS regions. While legitimate for
  disaster recovery, cross-region snapshot copies can be used for data exfiltration or
  to prepare snapshots for sharing with external accounts.
Runbook: |
  1. Find all snapshot copy operations by the user ARN in the past 24 hours to identify bulk copying patterns
  2. Check if cross-region snapshot copies are normal for this user by searching the past 90 days
  3. Look for snapshot sharing events in the target region in the 48 hours after this copy
Reference: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_CopySnapshot.html
Reports:
  MITRE ATT&CK:
    - TA0010:T1537  # Transfer Data to Cloud Account
DedupPeriodMinutes: 60
SummaryAttributes:
  - eventName
  - userIdentity:principalId
  - requestParameters:sourceRegion
  - awsRegion
  - requestParameters:sourceDBSnapshotIdentifier
  - p_any_aws_account_ids
Threshold: 1
Tests:
  - Name: Snapshot Copied Cross-Region
    ExpectedResult: true
    Log:
      eventVersion: "1.08"
      userIdentity:
        type: AssumedRole
        principalId: "AIDAI23HXS3EXAMPLE:user"
        arn: "arn:aws:sts::123456789012:assumed-role/DeveloperRole/user"
        accountId: "123456789012"
        accessKeyId: "ASIAIOSFODNN7EXAMPLE"
      eventTime: "2024-01-17T11:00:00Z"
      eventSource: rds.amazonaws.com
      eventName: CopyDBSnapshot
      awsRegion: us-west-2
      sourceIPAddress: "203.0.113.45"
      userAgent: "aws-cli/2.13.0"
      requestParameters:
        sourceDBSnapshotIdentifier: "arn:aws:rds:us-east-1:123456789012:snapshot:prod-backup-2024"
        targetDBSnapshotIdentifier: "prod-backup-2024-copy"
        sourceRegion: "us-east-1"
        kmsKeyId: "arn:aws:kms:us-west-2:123456789012:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        copyTags: true
      responseElements:
        dBSnapshotIdentifier: "prod-backup-2024-copy"
        dBSnapshotArn: "arn:aws:rds:us-west-2:123456789012:snapshot:prod-backup-2024-copy"
        status: "copying"
        sourceRegion: "us-east-1"
        sourceDBSnapshotIdentifier: "arn:aws:rds:us-east-1:123456789012:snapshot:prod-backup-2024"
      requestID: "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
      eventID: "f1e2d3c4-b5a6-7890-1234-567890abcdef"
      readOnly: false
      eventType: AwsApiCall
      managementEvent: true
      recipientAccountId: "123456789012"
      eventCategory: Management

  - Name: Cluster Snapshot Copied Cross-Region
    ExpectedResult: true
    Log:
      eventVersion: "1.08"
      userIdentity:
        type: IAMUser
        principalId: "AIDAI23HXS3EXAMPLE"
        arn: "arn:aws:iam::123456789012:user/contractor"
        accountId: "123456789012"
        accessKeyId: "AKIAIOSFODNN7EXAMPLE"
        userName: contractor
      eventTime: "2024-01-17T11:00:00Z"
      eventSource: rds.amazonaws.com
      eventName: CopyDBClusterSnapshot
      awsRegion: eu-west-1
      sourceIPAddress: "198.51.100.100"
      userAgent: "Boto3/1.26.0"
      requestParameters:
        sourceDBClusterSnapshotIdentifier: "arn:aws:rds:us-east-1:123456789012:cluster-snapshot:aurora-prod-backup"
        targetDBClusterSnapshotIdentifier: "aurora-prod-backup-eu"
        sourceRegion: "us-east-1"
        kmsKeyId: "arn:aws:kms:eu-west-1:123456789012:key/abcd1234-ab12-cd34-ef56-1234567890ab"
      responseElements:
        dBClusterSnapshotIdentifier: "aurora-prod-backup-eu"
        dBClusterSnapshotArn: "arn:aws:rds:eu-west-1:123456789012:cluster-snapshot:aurora-prod-backup-eu"
        status: "copying"
        sourceRegion: "us-east-1"
      requestID: "b2c3d4e5-f6a7-8901-bcde-f1234567890a"
      eventID: "g2f3e4d5-c6b7-8901-2345-678901bcdefg"
      readOnly: false
      eventType: AwsApiCall
      managementEvent: true
      recipientAccountId: "123456789012"
      eventCategory: Management

  - Name: Snapshot Copied Within Same Region - No Alert
    ExpectedResult: false
    Log:
      eventVersion: "1.08"
      userIdentity:
        type: AssumedRole
        principalId: "AIDAI23HXS3EXAMPLE:admin"
        arn: "arn:aws:sts::123456789012:assumed-role/AdminRole/admin"
        accountId: "123456789012"
        accessKeyId: "ASIAIOSFODNN7EXAMPLE"
      eventTime: "2024-01-17T11:00:00Z"
      eventSource: rds.amazonaws.com
      eventName: CopyDBSnapshot
      awsRegion: us-east-1
      sourceIPAddress: "10.0.1.100"
      userAgent: "console.amazonaws.com"
      requestParameters:
        sourceDBSnapshotIdentifier: "original-snapshot"
        targetDBSnapshotIdentifier: "copy-of-snapshot"
      responseElements:
        dBSnapshotIdentifier: "copy-of-snapshot"
        status: "copying"
      requestID: "c3d4e5f6-a7b8-9012-cdef-1234567890ab"
      eventID: "h3g4f5e6-d7c8-9012-3456-789012cdefgh"
      readOnly: false
      eventType: AwsApiCall
      managementEvent: true
      recipientAccountId: "123456789012"
      eventCategory: Management

  - Name: Copy Failed
    ExpectedResult: false
    Log:
      eventVersion: "1.08"
      userIdentity:
        type: IAMUser
        principalId: "AIDAI23HXS3EXAMPLE"
        arn: "arn:aws:iam::123456789012:user/developer"
        accountId: "123456789012"
        accessKeyId: "AKIAIOSFODNN7EXAMPLE"
        userName: developer
      eventTime: "2024-01-17T11:00:00Z"
      eventSource: rds.amazonaws.com
      eventName: CopyDBSnapshot
      awsRegion: us-west-2
      sourceIPAddress: "10.0.2.100"
      userAgent: "aws-cli/2.13.0"
      requestParameters:
        sourceDBSnapshotIdentifier: "arn:aws:rds:us-east-1:123456789012:snapshot:prod-backup"
        targetDBSnapshotIdentifier: "prod-backup-copy"
        sourceRegion: "us-east-1"
      errorCode: AccessDenied
      errorMessage: "User is not authorized to perform: rds:CopyDBSnapshot"
      requestID: "d4e5f6a7-b8c9-0123-def0-1234567890bc"
      eventID: "i4h5g6f7-e8d9-0123-4567-890123defghi"
      readOnly: false
      eventType: AwsApiCall
      managementEvent: true
      recipientAccountId: "123456789012"
      eventCategory: Management

Detection logic

Condition

eventSource eq "rds.amazonaws.com"
eventName in ["CopyDBSnapshot", "CopyDBClusterSnapshot"]
errorCode is_null
requestParameters.sourceRegion is_not_null
awsRegion is_not_null
requestParameters.sourceRegion cross_field_compare "awsRegion"

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
`awsRegion`	is_not_null	(no value, null check)
`errorCode`	is_null	(no value, null check)
`eventName`	in	`CopyDBClusterSnapshot` `CopyDBSnapshot`
`eventSource`	eq	`rds.amazonaws.com`
`requestParameters.sourceRegion`	cross_field_compare	`awsRegion` transforms: `op:ne`
`requestParameters.sourceRegion`	is_not_null	(no value, null check)

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	Source
`eventName`
`eventSource`
`awsRegion`
`recipientAccountId`
`sourceIPAddress`
`userAgent`
`userIdentity`
`sourceDBSnapshotIdentifier`	`requestParameters.sourceDBSnapshotIdentifier`
`sourceRegion`	`requestParameters.sourceRegion`

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`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)