Awesome

AWS Incident Response

Investigation of API activity using Athena and notification of actions using EventBridge

Use

For a slighly more pleasant viewing experience, use the GitHub pages link: https://easttimor.github.io/aws-incident-response/

For those on GitHub Pages already, the repo additionally contains Terraform resources for deploying Event Rules to catch high risk API events.

Introduction

This project explores useful CloudTrail events that support incident response and detection of misconfigurations. Documenting the queries and filters used to identify these CloudTrail events helps to:

• build a timeline of events
• understand the scope of the incident
• identify indicators of compromise
• decrease time to containment and recovery

Mis-configurations are important events to identify early. These configurations may introduce a vulnerability, but may also be an indicator of compromise.

Whether executed manually or by automating, this information may be used to develop incident response playbooks. These types of formalization activities promote a consistent, efficient, and effective response to security incidents.

NEW 2020-08-04 Addition of VPC Flow Log queries via Athena

Table of Contents

• AWS Incident Response
  • Introduction
• Table of Contents
  • Why Athena?
    • Getting Started
    • Alternatives
  • Why EventBridge?
• Incidents
  • General IAM Investigation
    • API Errors
    • Activity from potentially malicious source ip
    • S3 ListBuckets
  • Incident: Access Key Exposure
    • Find the IAM Principal and AWS Account associated with Access Key
    • All key usage
    • Activity for a specific IAM User
    • Look for user agent anomalies for key
    • Look for source ip anomalies
  • Incident: EC2 Instance Compromise
    • Recent API calls with a specific instanceId as the target resource
    • EC2 Instance profile - most frequent API calls
    • EC2 Instance profile - most denied API calls
    • All EC2 Instance Profiles - most denied instance profiles
    • All EC2 Instance Profiles - most denied event names
    • EC2 Instance Profile interacting with IAM
    • EC2 Instance Profile enumerating S3
  • General Purpose Queries
    • Most common API actions for a given day
    • Most common error codes
      • Principals getting denied the most
    • Common denied actions from specific principal (see above)
• API Watchlist
  • IAM
    • Root Credential Use
    • Remove MFA from an IAM User
    • All IAM Changes
    • Creation of IAM Principals
    • Privilege Escalation: IAM Policy
    • Add/Update Credentials
    • Privilege Escalation: Adding permissions
    • Privilege Escalation: Expand Access to an IAM Role
    • Modify Federated Access
  • S3
  • EC2
    • General
    • EBS Encryption Account-wide Setting
    • Share EBS Snapshot
    • Modify UserData
    • Network Access
    • Traffic Mirroring
    • Network Routing
  • Lambda
  • Disruption and Evasion
    • CloudTrail
      • CloudTrail Disruption
    • Config
      • Disrupt Config Recording, Evaluation, and Remediation
    • GuardDuty
      • GuardDuty Disruption
      • GuardDuty Recon
    • IAM Access Analyzer
    • Inspector
    • Macie(2)
    • EC2
      • Disrupt VPC Flow Logs
    • S3
      • Permissions Update
      • Data Management
    • SecurityHub
      • Terminology
      • API Actions
      • SecurityHub Service Disruption
      • SecurityHub Findings Disruption
    • Web Application Firewall (WAF)
• Network Flow Analysis
  • Manual Setup
    • Add table to Athena
    • Add date partition
  • Useful Queries
    • General concepts
    • Inbound Traffic
      • Accepted packets by port
      • Rejected packets by port
      • Volume by sourceaddress
      • Volume by destinationport
    • Outbound Traffic
      • Volume by desination
      • Volume by port
      • Rejected by port
      • Rejected by destination
    • Example: Connectionless LDAP Reflection Attack
• Useful CloudTrail fields
• Credit and References

Why Athena?

CloudTrail logs should be stored and archived in S3, where they are essentially useless unless integrated with another product or service. Amazon Athena allows you to query these JSON-formatted logs using standard SQL. This approach gives access to a potentially massive amount of CloudTrail data without the cost and effort of implementing Splunk, ElasticSearch, or storing in another database.

Getting Started

Athena charges for the data scanned for each query. You may only return one record, but will be charged for all data queried to match that record. By default, S3 data is not indexed, so Athena will inefficiently scan a LOT of data. There are also S3 charges (GET requests) that factor in at larger scale.

https://aws.amazon.com/athena/pricing/

But, we can make Athena faster and cost effective by creating partitions. Implement CloudTrail Partitioner. By default, Partitioner will create a virtual table for each AWS account so you don't scan an entire aggregated bucket. Partitioner will also add the following partitions:

• region
• year
• month
• day

Including these partitions in your SQL statements, as shown throughout this project, significantly improves query performance by limiting the amount of data scanned. Limiting the amount of data scanned saves money. For ad-hoc queries, such as those used for incident response, this cost is negligible.

https://github.com/duo-labs/cloudtrail-partitioner

Alternatives

• query direct from CloudTrail: no cost, very limiting query syntax
• query direct from CloudWatch Logs: higher cost than S3, fast query performance but weaker query syntax
• ingest logs in Splunk, ElasticSearch, etc: expensive

Why EventBridge?

EventBridge builds on CloudWatch Events and uses the same APIs. This is essentially CloudWatch Events.

Querying CloudTrail, even if automated, is best suited for ad-hoc response to finding misconfigurations and investigating incidents. Many of these configuration-related indicators of compromise can be detected in near real time. EventBridge allows for these pre-defined CloudTrail events to be filtered and integrated with numerous alerting methods (e.g. SNS) and event flows (e.g. Lambda, 3rd party SIEM).

This approach is independent of the Athena queries, but both approaches complement each other.

The Terraform section of this project repo includes deployable event filters with a basic SNS notification. Where applicable, Athena queries on this page are reflected in these event filters.

EventBridge is cheap for this use case.

https://aws.amazon.com/eventbridge/pricing/

Incidents

The following section builds a collection of common incidents and the Athena queries that may prove useful in response. These queries attempt to explain timeline, scope, impact, and surface indicators of compromise.

General IAM Investigation

Some of the queries in this section were inspired by the following Reference: https://wellarchitectedlabs.com/security/300_labs/300_incident_response_with_aws_console_and_cli/2_iam/

API Errors

select eventTime, eventSource, eventName, errorCode, errorMessage, responseElements, awsRegion, userIdentity.arn, sourceIPAddress, userAgent
from cloudtrail_000000000000
and year = '####' and month = '##'
and errorCode in ('Client.UnauthorizedOperation','Client.InvalidPermission.NotFound','Client.OperationNotPermitted','AccessDenied')
order by eventTime desc
limit 25

Activity from potentially malicious source ip

select eventTime, eventSource, eventName, awsRegion, userIdentity.arn, sourceIPAddress, userAgent
from cloudtrail_000000000000
and year = '####' and month = '##'
and sourceIPAddress = 'x.x.x.x'
order by eventTime desc
limit 25

S3 ListBuckets

The ListBuckets API action, used to enumerate buckets within an AWS account, is a potential indicator of compromise.

select eventTime, eventSource, eventName, awsRegion, errorCode, errorMessage, userIdentity.arn, sourceIPAddress, userAgent
from cloudtrail_000000000000
and year = '####' and month = '##'
and eventName = 'ListBuckets'
limit 25

Incident: Access Key Exposure

We are looking for the following:

• what actions has this key been used for, historically and currently?
• has this key been used from any odd locations?
• has this key been used from any odd user agents?
• dig for any signs of established persistence to include or data access

These queries must include all AWS Regions.

Find the IAM Principal and AWS Account associated with Access Key

select useridentity.principalId, useridentity.arn, useridentity.accountId, region
from cloudtrail_000000000000
where year = '####' and month = '##'
and useridentity.accesskeyid = 'AKIAxxxxxxxxxxxxxxxx'
limit 1

All key usage

Looking for high risk events that indicate establishing persistence, escalating permissions, resource creation (denial-of-wallet), data access (exfiltration). These actions may include:

• iam:CreateUser
• iam:CreateAccessKey
• iam:CreateLoginProfile
• iam:UpdateLoginProfile

Pay attention to all actions identified for priviledge escalation in this document.

select eventtime, eventsource, eventname, sourceipaddress, errorcode, useragent
from cloudtrail_000000000000
where useridentity.accesskeyid = 'AKIAxxxxxxxxxxxxxxxx'
and year = '####' and month = '##'

Activity for a specific IAM User

userIdentity.arn determined from the above query.

select eventtime, eventsource, eventname, errorcode, sourceipaddress, useragent
from cloudtrail_000000000000
where year = '####' and month = '##'
and userIdentity.arn = 'arn:aws:iam::000000000000:user/xxxxxxxx'
order by eventtime desc

Limit some noise.

select eventtime, eventsource, eventname, errorcode, sourceipaddress, useragent
from cloudtrail_000000000000
where year = '####' and month = '##'
and userIdentity.arn = 'arn:aws:iam::000000000000:user/xxxxxxxx'
and eventName not like 'Describe%'
and eventName not like 'List%'
and eventName not like 'Get%'
order by eventtime desc

Look for user agent anomalies for key

Determine "normal" for user agent string

select useragent, count(*) as total
from cloudtrail_000000000000
where useridentity.accesskeyid = 'AKIAxxxxxxxxxxxxxxxx'
and year = '####' and month = '##'
group by useragent
order by total desc

Assess activity for a specific user agent string; Conditions may be added to limit to a specific user or credential.

select eventtime, eventsource, eventname, sourceipaddress, errorcode
from cloudtrail_000000000000
where year = '####' and month = '##'
and useragent = 'seeAbove'

Group by user to include all access for a single user. This approach would be helpful if keys are rotated or a console login is used.

This value format is for an IAM user and not an assumed role

select useragent, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##'
and userIdentity.userName = 'xxxxxx'
group by useragent
order by total desc

Look for source ip anomalies

Group by sourceIpAddress for a specific access key.

select sourceipaddress, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##'
and useridentity.accesskeyid = 'AKIAxxxxxxxxxxxxxxxx'
group by sourceipaddress
order by total desc

Assess all activity for a specific source IP, typically one believed to be an adversary in the case of a compromised key.

select eventtime, eventsource, eventname, errorcode, useragent
from cloudtrail_000000000000
where sourceipaddress = 'seeAbove'
and year = '####'
and month = '##'

Group by user to include multiple credentials for a single user. This approach would be helpful if keys are rotated or a console login is used.

This value format is for an IAM user and not an assumed role

select sourceipaddress, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##'
and userIdentity.userName = 'xxxxxx'
group by sourceipaddress
order by total desc

Incident: EC2 Instance Compromise

EC2 instances may have an IAM Role attached to them. The combination of the instance and the role is called an "instance profile". When the role is assumed, the EC2 instance ID is used as the session name part of the Principal ARN in CloudTrail. We can identify actions of EC2 instances using the clause useridentity.principalid like '%:i-%' or a specific EC2 instance useridentity.principalid like '%:i-00000000000000000'

The actions of EC2 instances will typically be repetitive and persistent, because all actions are presumed to be initiated by software and not a human. Play close attention to any anomalous API calls. An attacker with access to an EC2 instance has access to any IAM permissions granted to that instance via the instance profile.

Recent API calls with a specific instanceId as the target resource

Very inefficient I know - room for improvement here

The CloudTrail UI provides resource name as search criteria. Note that resource name is not an actual key in the JSON so they're abstracting some query magic. Relevant events may not be included in this CloudTrail API query - otherwise stated, the below Athena query will show you more events for better or worse.

select eventTime, eventName, eventSource, userIdentity.arn
from cloudtrail_000000000000
where year = 'xxxx' and month = 'xx' and day = 'xx'
and (requestParameters like '%i-xxxxxxxxxxxxxxxxx%' or responseElements like '%i-xxxxxxxxxxxxxxxxx%')
and eventname not like 'Describe%'
and eventsource = 'ec2.amazonaws.com'
limit 25

EC2 Instance profile - most frequent API calls

select eventname, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-xxxxxxxxxxxxxxxxx'
group by eventname
order by total desc
limit 25

EC2 Instance profile - most denied API calls

select eventname, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-xxxxxxxxxxxxxxxxx'
and errorcode = 'AccessDenied'
group by eventname
order by total desc
limit 25

All EC2 Instance Profiles - most denied instance profiles

select useridentity.principalid, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-%'
and errorcode = 'AccessDenied'
group by useridentity.principalid
order by total desc
limit 25

All EC2 Instance Profiles - most denied event names

select eventsource,eventname,count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-%'
and eventname <> 'AssumeRole'
and errorcode = 'AccessDenied'
group by eventsource,eventname
order by total desc
limit 25

EC2 Instance Profile interacting with IAM

EC2 instances rarely have a need for IAM actions. Include an and eventname <> clause if legitimate actions are found that muddy the search results.

select useridentity.principalid,eventsource,eventname,count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-%'
and eventsource = 'iam.amazonaws.com'
group by useridentity.principalid,eventsource,eventname
order by total desc
limit 25

EC2 Instance Profile enumerating S3

EC2 instances should know exactly which S3 buckets to they need. The ListBuckets action is a strong indicator of compromise...or bad development practices.

select useridentity.principalid,eventsource,eventname,count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and useridentity.principalid like '%:i-%'
and eventsource = 's3.amazonaws.com'
and eventname = 'ListBuckets'
group by useridentity.principalid,eventsource,eventname
order by total desc
limit 25

General Purpose Queries

These queries are useful for exploring potential issues and building upon for threat hunting.

Most common API actions for a given day

select eventname,count(*) as total
from cloudtrail_000000000000 
where year = '####' and month = '##' and day = '##'
group by eventname
order by total desc

Most common error codes

select errorcode, count(errorcode) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
group by errorcode
order by total desc

Principals getting denied the most

select useridentity.principalid, count(*) as deniedactions
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and errorcode = 'AccessDenied'
group by useridentity.principalid
order by deniedactions desc
limit 25

Common denied actions from specific principal (see above)

select eventname, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and errorcode = 'AccessDenied'
and useridentity.principalid = 'AROAxxxxxxxxxxxxxxxxx:i-xxxxxxxxxxxxxxxxx'
group by eventname
order by total desc

API Watchlist

these are better suited for event driven alerting, and that's what the Terraform in this repo aims to provide.

IAM

Root Credential Use

• Technique: T1078 Valid Accounts
• Tactic:
  • TA0001 Initial Access
  • TA0003 Persistence
• GuardDuty:
  • Policy:IAMUser/RootCredentialUsage

All Root account events

select * 
from cloudtrail_000000000000
where year = '####' and month = '##' 
and useridentity.type = 'Root'

Only ConsoleLogin event from Root

select *
from cloudtrail_000000000000
where year = '####' and month = '##' 
and eventname = 'ConsoleLogin'
and useridentity.type = 'Root'

Remove MFA from an IAM User

While IAM Policy may still include a condiion that requires MFA, removing MFA from an IAM User enables a pivot to that principal.

• Technique: T1531 Account Access Removal

select *
from cloudtrail_000000000000
where year = '####' and month = '##' 
and eventname IN ('DeactivateMFADevice', 'DeleteVirtualMFADevice')

All IAM Changes

• GuardDuty
  • Persistence:IAMUser/UserPermissions

The IAM API has numerous actions for establishing persistence and expanding permissions. The following query removes read only actions.

select useridentity.principalid, eventname, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'iam.amazonaws.com'
and eventname not like 'Get%' 
and eventname not like 'List%'
and eventname not like 'Generate%'
group by useridentity.principalid, eventname
order by total desc

Creation of IAM Principals

select useridentity.principalid, eventname, count(*) as total
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'iam.amazonaws.com'
and evenname in ('CreateUser','CreateRole','CreateServiceLinkedRole')

Privilege Escalation: IAM Policy

IAM Policy updates used to expand permissions of associated principals (IAM Users, IAM Roles).

• RhinoSec
  • (1) Creating a new policy version
  • (2) Setting the default policy version to an existing version

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventName IN ('CreatePolicyVersion','SetDefaultPolicyVersion')
order by eventtime desc

Add/Update Credentials

• RhinoSec:
  • (4) Creating a new user access key
  • (5) Creating a new login profile
  • (6) Updating an existing login profile
• Pacu:
  • iam__backdoor_users_keys
  • iam__backdoor_users_password

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventName IN ('CreateAccessKey', 'UpdateAccessKey',
'CreateLoginProfile','UpdateLoginProfile',
'CreateVirtualMFADevice','DeactivateMFADevice','DeleteVirtualMFADevice','EnableMFADevice'
'CreateServiceSpecificCredential','UpdateServiceSpecificCredential',
'ResetServiceSpecificSredential','DeleteServiceSpecificCredential',
'UploadServerCertificate','DeleteServerCertificate',
'UploadSigningCertificate','UpdateSigningCertificate','DeleteSigningCertificate',
'UploadSSHPublicKey','UpdateSSHPublicKey','DeleteSSHPublicKey'
)
order by eventtime desc

Privilege Escalation: Adding permissions

Permission expansion may include disassociating a principal from an IAM Policy due to the removal of explicit Deny effects.

• Technique:
  • T1098 Account Manipulation
• Tactic:
  • TA0003 Persistence
  • TA0006 Account Manipulation
• RhinoSec:
  • (7) Attaching a policy to a user
  • (8) Attaching a policy to a group
  • (9) Attaching a policy to a role
  • (10) Creating/updating an inline policy for a user
  • (11) Creating/updating an inline policy for a group
  • (12) Creating/updating an inline policy for a role
  • (13) Adding a user to a group

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventSource = 'iam.amazonaws.com' 
and eventName IN ('AttachUserPolicy', 'DetachUserPolicy',
'AttachRolePolicy', 'DetachRolePolicy',
'PutUserPolicy','PutGroupPolicy','PutRolePolicy',
'DeleteUserPolicy','DeleteGroupPolicy','DeleteRolePolicy',
'DeleteRolePermissionsBoundary')
order by eventtime desc

Privilege Escalation: Expand Access to an IAM Role

• RhinoSec
  • (14) Updating the AssumeRolePolicyDocument of a role
• Pacu
  • iam__backdoor_assume_role

Updating a trust policy (UpdateAssumerolePolicy) allows a service, local account principal, or external account to assume the associate IAM Role and its permissions.

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventSource = 'iam.amazonaws.com' 
and eventName IN ('UpdateAssumeRolePolicy')
order by eventtime desc

Modify Federated Access

• Tactics
  • TA0001 Initial Access
  • TA0003 Persistence
• Techniques
  • T1098 Account Manipulation
  • T1199 Trusted Relationship

Adding a new identity provider (CreateSAMLProvider) also requires adding or updating an IAM's Role's trust policy.

Updating the metadata (UpdateSAMLProvider) for a SAML IdP would hijack an existing trusted relationship, but break existing federated access.

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventName IN ('CreateSAMLProvider','UpdateSAMLProvider','DeleteSAMLProvider',
'CreateOpenIDConnectProvider','DeleteOpenIDConnectProvider','UpdateOpenIDConnectProviderThumbprint',
'AddClientIDToOpenIDConnectProvider','RemoveClientIDFromOpenIDConnectProvider')
order by eventtime desc

S3

• Tactics
  • TA0005 Defense Evasion
  • TA0010 Exfiltration
  • TA0006 Credential Access
• Techniques
  • T1029 Scheduled Transfer
  • T1537 Transfer Data to Cloud Account
  • T1081 Credentials in Files
• GuardDuty
  • Stealth:S3/ServerAccessLoggingDisabled

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname in ('DeleteBucket','DeleteBucketPolicy',
'PutBucketAcl','PutBucketCORS','PutBucketPolicy','PutReplicationConfiguration',
'PutBucketLogging','PutEncryptionConfiguration','PutLifecycleConfiguration','PutObjectAcl',
'RestoreObject')
order by eventtime desc

For object access logging suppression, in addition to s3:PutBucketLogging see also cloudtrail:PutEventSelectors for logging configuration of data events.

EC2

General

• Tactics
  • TA0010 Exfiltration
  • TA0003 Persistence
• Technique
  • T1108 Redundant Access

EBS Encryption Account-wide Setting

• Technique
  • T1492 Stored Data Manipulation
  • T1486 Data Encrypted for Impact
• Tactic
  • TA0040 Impact

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'ec2.amazonaws.com'
and eventname IN ('EnableEbsEncryptionByDefault','DisableEbsEncryptionByDefault')

Share EBS Snapshot

• Tactics
  • TA0010 Exfiltration
• Techniques
  • T1537 Transfer Data to Cloud Account

--user-ids 000000000000 is used to share with an external account

--group-names all is used to share publicly

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'ec2.amazonaws.com'
and eventname = 'ModifySnapshotAttribute'

Modify UserData

• Technique
  • T1108 Redundant Access
  • T1089 Disabling Security Tools
  • T1496 Resource Hijacking
• Tactic
  • TA0003 Persistence
  • TA0005 Defensive Evasion
• General
  • Tampering / Defacement
  • Data exfiltration
  • Secrets collection
  • Pivot from trusted access

An EC2 instance will execute UserData with root-level permissions on start/re-start. The instance must be in a stopped state to configure the userdata update.

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname = 'ModifyInstanceAttribute'
and requestParameters like '%userData%'

Network Access

• Technique
  • T1108 Redundant Access
  • T1089 Disabling Security Tools
• Tactic
  • TA0003 Persistence
  • TA0005 Defensive Evasion

Network Access Control List (NACL) configuration

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN (
   'CreateNetworkAcl',
   'CreateNetworkAclEntry',
   'DeleteNetworkAcl',
   'DeleteNetworkAclEncry'
   )
order by eventtime desc

Security group configuration

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN (
   'AuthorizeSecurityGroupIngress',
   'AuthorizeSecurityGroupEgress'
   'CreateSecurityGroup',
   'ModifyInstanceAttribute'
   )
order by eventtime desc

Traffic Mirroring

Traffic Mirroring is a full packet capture (pcap) capability that may be used by an adversary to exfil secrets and sensitive data from unencrypted internal traffic. Within a VPC a traffic mirroring session is established with collection filter rules that identify what traffic to collect and forward to a target.

https://docs.aws.amazon.com/vpc/latest/mirroring/what-is-traffic-mirroring.html https://docs.aws.amazon.com/vpc/latest/mirroring/traffic-mirroring-filters.html

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN (
    'CreateTrafficMirrorFilter',
    'CreateTrafficMirrorFilterRule',
    'CreateTrafficMirrorSession',
    'CreateTrafficMirrorTarget'
    )

Network Routing

Actions in this category have a high degree of legitimate use and are most helpful when correlated with other IoCs

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN (
    'CreateRoute',
    'CreateRouteTable',
    'DeleteRouteTable',
    'DeleteRoute',
    'DisassociateRouteTable',
    'ReplaceRoute',
    'ReplaceRouteTableAssociation' 
    )
order by eventtime desc

The following events are less common than routing changes above, but should be correlated with other IoCs

These events are high impact to a VPC's ingress/egress traffic flow

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN (
    'CreateCustomerGateway',
    'DeleteCustomerGateway',
    'AttachInternetGateway',
    'CreateInternetGateway',
    'DeleteInternetGateway',
    'DetachInternetGateway'
)
order by eventtime desc

Lambda

No API event in isolation should be concerning, so the importance of establishing context around Lambda service events is critical. Attackers may use existing Lambda functions to inherit elevated permissions as a pivot, for establishing persistence, or for accessing data. The actions indicated in this section are the most important to look for, but are by no means the only Lambda actions to care about in incident response.

• Technique
  • T1108 Redundant Access
  • T1089 Disabling Security Tools
  • T1496 Resource Hijacking
• Tactic
  • TA0003 Persistence
  • TA0005 Defensive Evasion
• RhinoSec
  • (15) Passing a role to a new Lambda function, then invoking it
  • (17) Updating the code of an existing Lambda function
• General
  • Tampering / Defacement
  • Data exfiltration
  • Secrets collection
  • Pivot from trusted access

Disruption and Evasion

CloudTrail

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion
• GuardDuty Findings:
  • Stealth:IAMUser/CloudTrailLoggingDisabled
  • Stealth:IAMUser/LoggingConfigurationModified
• Pacu:
  • detection__disruption - DeleteTrail (del), StopLogging (dis), UpdateTrail (min)

CloudTrail Disruption

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('DeleteTrail','StopLogging','UpdateTrail',
'PutEventSelectors')

To-do:

• bucket deletion
• bucket object deletion
• bucket tampering

Config

Disrupt Config Recording, Evaluation, and Remediation

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion
• Pacu
  • detection__disruption | DeleteConfigurationRecorder (del), StopConfigurationRecorder (dis)

CloudTrail may still log resource configuration actions Goals here are to prevent resource configuration history (for forensics), non-compliance detection, and remediation Offensive capability may be introduced through Systems Manager Automation as remediation action

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'config.amazonaws.com'
and eventname IN ('DeleteConfigRule','DeleteOrganizationConfigRule',
'DeleteConfigurationAggregator','DeleteConfigurationRecorder',
'DeleteConformancePack','DeleteOrganizationConformancePack',
'DeleteDeliveryChannel','PutDeliveryChannel',
'DeleteRemediationConfiguration','DeleteRetentionConfiguration',
'PutConfigRule', 'PutConfigurationAggregator','PutConformancePack',
'PutOrganizationConfigRule','PutOrganizationConformancePack',
'PutRemediationConfigurations','PutRemediationExceptions',
'PutRetentionConfiguration',
'StopConfigurationRecorder')

To-do:

• S3 Bucket disruption
• Disable stream configuration changes and notifications to an Amazon SNS topic
• Explain use of AWS Config role for privilege escalation

GuardDuty

GuardDuty is AWS' managed threat detection services. The service evaluates VPC Flow Logs, CloudTrail, and Route53 query logs using signature and machine learning-backed detection methods. There are numerous methods for bypassing detection both through GuardDuty re-configuration and operating within its blind spots.

GuardDuty Disruption

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion
• Pacu
  • guardduty__whitelist_ip - UpdateIPSet
  • detection__disruption - DeleteDetector, UpdateDetector --no-enable

Disable GuardDuty in the Web console translates to the DeleteDetector API call and Pacu's Delete option

Suspend GuardDuty in the Web console translates to the UpdateDetector --no-enable API call and Pacu's Disable option

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('CreateFilter','CreateIPSet','CreateSampleFindings','CreateThreatIntelSet',
'DeleteDetector','DeleteMembers','DeletePublishingDestination','DeleteThreatIntelSet',
'DisassociateFromMasterAccount','DisassociateMembers','StopMonitoringMembers',
'UpdateDetector','UpdateFilter','UpdateIPSet','UpdatePublishingDestination','UpdateThreatIntelSet')
order by eventtime desc

GuardDuty Recon

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('ListMembers','GetMembers',
'ListDetectors','GetDetector',
'ListFilters','GetFilter',
'ListIPSets','GetIPSet',
'ListThreatIntelSets','GetThreatIntelSet')
order by eventtime desc

IAM Access Analyzer

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('CreateArchiveRule','DeleteAnalyzer',
'UpdateArchiveRule','UpdateFindings')
order by eventtime desc

Note: organizations.amazonaws.com has an API action for DeregisterDelegatedAdministrator

Inspector

https://docs.aws.amazon.com/IAM/latest/UserGuide/list_amazoninspector.html

https://docs.aws.amazon.com/cli/latest/reference/inspector/index.html

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('DeleteAssessmentRun','DeleteAssessmentTarget',
'DeleteAssessmentTemplate','UnsubscribeFromEvent','UpdateAssessmentTarget')
order by eventtime desc

Macie(2)

This section applies to the new Macie macie2.amazonaws.com which is not Macie "classic"

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventname IN ('ArchiveFindings','CreateFindingsFilter',
'DeleteMember','DisassociateFromMasterAccount','DisassociateMember',
'DisableMacie',
'UpdateFindingsFilter','UpdateMacieSession','UpdateMemberSession','DisableOrganizationAdminAccount',
'UpdateClassificationJob','UpdateFindingsFilter')
order by eventtime desc

Note that DeregisterDelegatedAdministrator is an eventsource organizations.amazonaws.com

EC2

Disrupt VPC Flow Logs

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'ec2.amazonaws.com'
and eventname = 'DeleteFlowLogs'

Note: GuardDuty, if enabled, monitors VPC Flow Logs independent of logging configuration. This disruptions primarily impacts custom monitoring solutions and 3rd party software.

S3

• Tactic
  • TA0009 Collection
  • TA0010 Exfiltration
• Technique
  • T1530 Data from Cloud Storage Object
  • T1029 Scheduled Transfer
  • T1537 Transfer Data to Cloud Account

Permissions Update

select eventTime, eventSource, eventName, awsRegion, errorCode, errorMessage, userIdentity.arn, sourceIPAddress, requestParameters
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 's3.amazonaws.com'
and eventname in (
    'PutAccessPointPolicy',
    'PutAccountPublicAccessBlock',
    'PutBucketAcl',
    'PutBucketCORS',
    'PutBucketPolicy',
    'PutBucketPublicAccessBlock',
    'PutObjectAcl'
)
order by eventTime desc

API Actions

Data Management

select eventTime, eventSource, eventName, awsRegion, errorCode, errorMessage, userIdentity.arn, sourceIPAddress, requestParameters
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 's3.amazonaws.com'
and eventname in (
    'PutBucketLogging',
    'PutBucketWebsite',
    'PutEncryptionConfiguration',
    'PutLifecycleConfiguration',
    'PutReplicationConfiguration',
    'ReplicateObject',
    'RestoreObject'
)
order by eventTime desc

API Actions

SecurityHub

References:

• https://docs.aws.amazon.com/IAM/latest/UserGuide/list_awssecurityhub.html
• More info: https://aws.amazon.com/security-hub/faqs/

Terminology

API Actions

SecurityHub Service Disruption

• Technique
  • T1089 Disabling Security Tools
  • T1054 Indicator Blocking
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'securityhub.amazonaws.com'
and eventname in ('BatchDisableStandards',
'DeleteActionTarget','DeleteMembers',
'DisableImportFindingsForProduct','DisableSecurityHub',
'DisassociateFromMasterAccount','DisassociateMembers',
'UpdateActionTarget','UpdateStandardsControl')

SecurityHub Findings Disruption

• Technique
  • T1054 Indicator Blocking
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where year = '####' and month = '##' and day = '##'
and eventsource = 'securityhub.amazonaws.com'
and eventname in ('BatchUpdateFindings',
'DeleteInsight',
'UpdateFindings','UpdateInsight')

Web Application Firewall (WAF)

• Technique
  • T1089 Disabling Security Tools
• Tactic
  • TA0005 Defensive Evasion

select *
from cloudtrail_000000000000
where (year = '####' and month = '##' and day = '##')
and eventname in ('DeleteFirewallManagerRuleGroups','DeleteIPSet',
'DeleteLoggingConfiguration','DeletePermissionPolicy','DeleteRegexPatternSet',
'DeleteRuleGroup','DeleteWebACL','DisassociateWebACL',
'PutLoggingConfiguration','PutPermissionPolicy',
'UpdateIPSet','UpdateRegexPatternSet','UpdateRuleGroup','UpdateWebACL')

Network Flow Analysis

This is a proof-of-concept description. Expected changes for an enterprise implementation include:

• automated partitioning of account, region, year, month, day
• update S3 path per your environment

Pre-requisites include:

• Configuration of VPC Flow Logs with an S3 target
• Flow Log configuration for ALL traffic
• Resources operating within a VPC

Additional query capabilities are introduced by enriching Flow Logs with additional metadata.

Reference: https://aws.amazon.com/blogs/aws/learn-from-your-vpc-flow-logs-with-additional-meta-data/

Manual Setup

Reference: https://docs.aws.amazon.com/athena/latest/ug/vpc-flow-logs.html

Add table to Athena

CREATE EXTERNAL TABLE IF NOT EXISTS vpc_flow_logs_000000000000 (
  version int,
  account string,
  interfaceid string,
  sourceaddress string,
  destinationaddress string,
  sourceport int,
  destinationport int,
  protocol int,
  numpackets int,
  numbytes bigint,
  starttime int,
  endtime int,
  action string,
  logstatus string
)
PARTITIONED BY (`date` date)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ' '
LOCATION 's3://{bucket_name}/AWSLogs/000000000000/vpcflowlogs/{region}/'
TBLPROPERTIES ("skip.header.line.count"="1");

Add date partition

Partitions limits the query return set for speed and cost savings.

ALTER TABLE vpc_flow_logs_000000000000
ADD PARTITION (`date`='yyyy-mm-dd')
location 's3://bucket_name}/AWSLogs/000000000000/vpcflowlogs/{region}/yyyy/mm/dd';

Useful Queries

General concepts

Packet count proves useful for surfacing a high volume of traffic on protocols with smaller payload.

Inbound Traffic

Accepted packets by port

This is the traffic (packet count) allowed to reach your resource destinationaddress is the private IP of your resource

select destinationport, sum(numpackets) as packets
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
and action = 'ACCEPT'
group by destinationport
order by packets desc
limit 10

Rejected packets by port

This is the traffic (packet count) blocked from reaching your resource. REJECTED traffic may be due to a NACL Deny rule or lack of a security group rule. destinationaddress is the private IP of your resource

select destinationport, sum(numpackets) as packets
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
and action = 'REJECT'
group by destinationport
order by packets desc
limit 10

Volume by sourceaddress

destinationaddress is the private IP of your resource

select sourceaddress, sum(numbytes) as volume
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
group by sourceaddress
order by volume desc
limit 10

Volume by destinationport

destinationaddress is the private IP of your resource

select destinationport, sum(numbytes) as volume
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
group by destinationport
order by volume desc
limit 10

Assess specific time range

destinationaddress is the private IP of your resource starttime and endtime uses epoch

Reference: https://www.epochconverter.com/

select *
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd') 
and destinationaddress = 'x.x.x.x'
and starttime > 1596225600
and endtime < 1596226200

Outbound Traffic

Volume by desination

sourceaddress is the private IP of your resource

select destinationaddress, sum(numbytes) as volume
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and sourceaddress = 'x.x.x.x'
group by destinationaddress
order by volume desc
limit 10

Volume by port

destinationaddress is the private IP of your resource

select destinationport, sum(numbytes) as volume
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and sourceaddress = 'x.x.x.x'
group by destinationport
order by volume desc
limit 10

Assess specific time range

source is the private IP of your resource starttime and endtime uses epoch

Reference: https://www.epochconverter.com/

select *
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd') 
and sourceaddress = 'x.x.x.x'
and starttime > 1596225600
and endtime < 1596226200

Rejected by port

This is the traffic (packet count) allowed to reach your resource destinationaddress is the private IP of your resource

select destinationport, sum(numpackets) as packets
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
and action = 'ACCEPT'
group by destinationport
order by packets desc
limit 10

Rejected by destination

select destinationaddress, sum(numpackets) as packets
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and sourceaddress = 'x.x.x.x'
and action = 'REJECT'
group by destinationaddress
order by packets desc
limit 10

Example: Connectionless LDAP Reflection Attack

destinationaddress is your resource being used in the attack protocol is 17/UDP destinationport is 389/LDAP

select sourceaddress, sum(numpackets) as packets
from vpc_flow_logs_000000000000
WHERE date = DATE('yyyy-mm-dd')
and destinationaddress = 'x.x.x.x'
and protocol = 17
and destinationport = 389
group by sourceaddress
order by packets desc

Useful CloudTrail fields

References

• https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-event-reference-record-contents.html
• https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-event-reference-user-identity.html
• https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-log-file-examples.html#error-code-and-error-message

Credit and References

• https://rhinosecuritylabs.com/aws/aws-privilege-escalation-methods-mitigation/
• https://medium.com/voogloo/which-cloud-trail-calls-are-important-for-security-teams-26003d9939ec
• https://github.com/elastic/detection-rules/tree/main/rules/aws
• https://github.com/duo-labs/cloudtrail-partitioner
• https://wellarchitectedlabs.com/security/