AWSCloudTrail - Tampering to AWS CloudTrail logs

Status: available
Severity: high
Time window: 1d
Group by: AWSRegion, AccountName, AccountUPNSuffix, EventName, EventSource, EventTypeName, RecipientAccountId, SessionMfaAuthenticated, SourceIpAddress, UserAgent, UserIdentityAccountId, UserIdentityPrincipalid, UserIdentityUserName
Source: github.com/Azure/Azure-Sentinel

Detects successful attempts to disable, delete, or weaken AWS logging telemetry, including CloudTrail, CloudWatch/EventBridge, and VPC flow logs. This behavior can indicate defense evasion and deliberate reduction of incident visibility by an attacker.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685.002` Disable or Modify Tools: Disable or Modify Cloud Log

Telemetry coverage

Platform	Record / event type
AWS	CloudTrail event `DeleteTrail`: Deletes a CloudTrail trail, permanently stopping the delivery of log files for that trail to its configured S3 bucket.
AWS	CloudTrail event `StopLogging`: Suspends CloudTrail logging for a trail, halting the delivery of new log files while preserving the trail configuration.
AWS	CloudTrail event `UpdateTrail`: Updates the settings of an existing CloudTrail trail, such as its S3 bucket, SNS topic, or log file validation configuration.
AWS	CloudTrail event `DeleteFlowLogs`: Deletes one or more VPC flow logs.
AWS	CloudTrail event `DeleteEventBus`: Deletes the specified custom event bus or partner event bus.
AWS	CloudTrail event `DeleteLogGroup`: Deletes the specified CloudWatch Logs log group and all its associated log streams, subscription filters, metric filters, and retention policies.

Rules detecting the same action

These rules filter on the same operation.

A CloudTrail Was Created or Updated (Panther)
Account Security Configuration Changed (Panther)
ASL AWS Defense Evasion Delete Cloudtrail (Splunk)
ASL AWS Defense Evasion Delete CloudWatch Log Group (Splunk)
ASL AWS Defense Evasion Stop Logging Cloudtrail (Splunk)
ASL AWS Defense Evasion Update Cloudtrail (Splunk)
AWS Lateral Movement from Kubernetes SA via AssumeRoleWithWebIdentity (Elastic)
AWS VPC Flow Logs Deleted (Sigma)

Rule body

id: 633a91df-d031-4b6e-a413-607a61540559
name: AWSCloudTrail - Tampering to AWS CloudTrail logs
description: |
  Detects successful attempts to disable, delete, or weaken AWS logging telemetry, including CloudTrail,
  CloudWatch/EventBridge, and VPC flow logs. This behavior can indicate defense evasion and deliberate reduction
  of incident visibility by an attacker.
severity: High
status: Available
requiredDataConnectors:
  - connectorId: AWS
    dataTypes:
      - AWSCloudTrail
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - DefenseEvasion
relevantTechniques:
  - T1562.008
query: |
      let EventNameList = dynamic(["UpdateTrail","DeleteTrail","StopLogging","DeleteFlowLogs","DeleteEventBus","DeleteLogGroup"]);
      AWSCloudTrail
      | where (EventName in~ (EventNameList) or (EventName == "UpdateTrail" and (parse_json(RequestParameters).enableLogFileValidation) == false) or (EventName == "UpdateTrail" and (parse_json(RequestParameters).isMultiRegionTrail) == false)) and isempty(ErrorMessage) and isempty(ErrorCode)
      | extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
      | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
      | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
      | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
       AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
      | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by EventName, EventTypeName, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, UserIdentityPrincipalid, UserAgent, 
      UserIdentityUserName, SessionMfaAuthenticated, SourceIpAddress, AWSRegion, EventSource
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: AccountUPNSuffix
      - identifier: CloudAppAccountId
        columnName: RecipientAccountId
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIpAddress
customDetails:
  EventName: EventName
  EventTypeName: EventTypeName
  EventSource: EventSource
  AWSRegion: AWSRegion
alertDetailsOverride:
  alertDisplayNameFormat: 'AWS log tampering attempt: {{EventName}} by {{AccountName}}'
  alertDescriptionFormat: 'Detected {{EventName}} in {{AWSRegion}} affecting account {{RecipientAccountId}} logging telemetry.'
version: 1.0.5
kind: Scheduled

Stages and Predicates

Parameters

let EventNameList = dynamic(["UpdateTrail","DeleteTrail","StopLogging","DeleteFlowLogs","DeleteEventBus","DeleteLogGroup"]);

Stage 1: `source`

AWSCloudTrail

Stage 2: `where`

| where (EventName in~ (EventNameList) or (EventName == "UpdateTrail" and (parse_json(RequestParameters).enableLogFileValidation) == false) or (EventName == "UpdateTrail" and (parse_json(RequestParameters).isMultiRegionTrail) == false)) and isempty(ErrorMessage) and isempty(ErrorCode)

Stage 3: `extend` (4 consecutive steps)

| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
| extend UserName = tostring(split(UserIdentityArn, '/')[-1])
| extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
| extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
 AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")

Stage 4: `summarize`

| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated) by EventName, EventTypeName, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, UserIdentityPrincipalid, UserAgent, 
UserIdentityUserName, SessionMfaAuthenticated, SourceIpAddress, AWSRegion, EventSource

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ErrorCode`	is_null	(no value, null check)	`field:"aws::errorCode" kind:is_null`
`ErrorMessage`	is_null	(no value, null check)	`field:"aws::errorMessage" kind:is_null`
`EventName`	eq	`UpdateTrail`	`field:"aws::eventName" kind:eq value:"UpdateTrail"`
`EventName`	in	`DeleteEventBus` `DeleteFlowLogs` `DeleteLogGroup` `DeleteTrail` `StopLogging` `UpdateTrail`	`field:"aws::eventName" kind:in`
`enableLogFileValidation`	eq	`false`	`field:"enableLogFileValidation" kind:eq value:"false"`
`isMultiRegionTrail`	eq	`false`	`field:"isMultiRegionTrail" kind:eq value:"false"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`AWSRegion`	`summarize`
`AccountName`	`summarize`
`AccountUPNSuffix`	`summarize`
`EndTimeUtc`	`summarize`
`EventName`	`summarize`
`EventSource`	`summarize`
`EventTypeName`	`summarize`
`RecipientAccountId`	`summarize`
`SessionMfaAuthenticated`	`summarize`
`SourceIpAddress`	`summarize`
`StartTimeUtc`	`summarize`
`UserAgent`	`summarize`
`UserIdentityAccountId`	`summarize`
`UserIdentityPrincipalid`	`summarize`
`UserIdentityUserName`	`summarize`