Name:AWS AMI Attribute Modification for Exfiltration id:f2132d74-cf81-4c5e-8799-ab069e67dc9f version:4 date:2024-09-30 author:Bhavin Patel, Splunk status:production type:TTP Description:The following analytic detects suspicious modifications to AWS AMI attributes, such as sharing an AMI with another AWS account or making it publicly accessible. It leverages AWS CloudTrail logs to identify these changes by monitoring specific API calls. This activity is significant because adversaries can exploit these modifications to exfiltrate sensitive data stored in AWS resources. If confirmed malicious, this could lead to unauthorized access and potential data breaches, compromising the confidentiality and integrity of organizational information. Data_source:
-AWS CloudTrail ModifyImageAttribute
search:`cloudtrail` eventName=ModifyImageAttribute (requestParameters.launchPermission.add.items{}.userId = * OR requestParameters.launchPermission.add.items{}.group = all) | rename requestParameters.launchPermission.add.items{}.group as group_added | rename requestParameters.launchPermission.add.items{}.userId as accounts_added | eval ami_status=if(match(group_added,"all") ,"Public AMI", "Not Public") | stats count min(_time) as firstTime max(_time) as lastTime values(group_added) values(accounts_added) as accounts_added values(ami_status) by src_ip region eventName userAgent user_arn aws_account_id userIdentity.principalId | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)` | `aws_ami_attribute_modification_for_exfiltration_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:It is possible that an AWS admin has legitimately shared a snapshot with others for a specific purpose. References: -https://labs.nettitude.com/blog/how-to-exfiltrate-aws-ec2-data/ -https://stratus-red-team.cloud/attack-techniques/AWS/aws.exfiltration.ec2-share-ami/ -https://hackingthe.cloud/aws/enumeration/loot_public_ebs_snapshots/ drilldown_searches: name:'View the detection results for - "$aws_account_id$"' search:'%original_detection_search% | search aws_account_id = "$aws_account_id$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$aws_account_id$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$aws_account_id$") starthoursago=168 | 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:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Suspicious Cloud Instance Activities' - 'Data Exfiltration' asset_type:EC2 Snapshot confidence:80 impact:100 message:AWS AMI from account $aws_account_id$ is shared externally with $accounts_added$ from $src_ip$ or AMI made is made Public. mitre_attack_id: - 'T1537' observable: name:'user_arn' type:'User' - role: - 'Attacker' name:'src_ip' type:'IP Address' - role: - 'Attacker' name:'aws_account_id' type:'Other' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'eventName' - 'user_arn' - 'src_ip' - 'requestParameters.attributeType' - 'aws_account_id' - 'vendor_region' - 'user_agent' - 'userIdentity.principalId' risk_score:80 security_domain:threat
