Name:ASL AWS EC2 Snapshot Shared Externally id:00af8f7f-e004-446b-9bba-2732f717ae27 version:1 date:2024-12-17 author:Patrick Bareiss, Splunk status:production type:TTP Description:The following analytic detects when an EC2 snapshot is shared publicly by analyzing AWS CloudTrail events. This detection method leverages CloudTrail logs to identify modifications in snapshot permissions, specifically when the snapshot is shared outside the originating AWS account. This activity is significant as it may indicate an attempt to exfiltrate sensitive data stored in the snapshot. If confirmed malicious, an attacker could gain unauthorized access to the snapshot's data, potentially leading to data breaches or further exploitation of the compromised information. Data_source:
-ASL AWS CloudTrail
search:`amazon_security_lake` api.operation=ModifySnapshotAttribute | spath input=api.request.data path=createVolumePermission.add.items{}.group output=group | search group=all | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by api.operation actor.user.uid actor.user.account.uid http_request.user_agent src_endpoint.ip cloud.region api.request.data | rename actor.user.uid as user, src_endpoint.ip as src_ip, cloud.region as region, http_request.user_agent as user_agent | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `asl_aws_ec2_snapshot_shared_externally_filter`
how_to_implement:The detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App. 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-ebs-snapshot/ -https://hackingthe.cloud/aws/enumeration/loot_public_ebs_snapshots/ 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 ("$user$") 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:60 message:AWS EC2 snapshot from user $user$ is shared publicly by user $user$ mitre_attack_id: - 'T1537' observable: name:'user' type:'User' - role: - 'Victim' name:'src_ip' type:'IP Address' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - 'api.operation' - 'actor.user.uid' - 'actor.user.account.uid' - 'api.request.data' - 'http_request.user_agent' - 'src_endpoint.ip' - 'src_endpoint.domain' - 'cloud.region' risk_score:48 security_domain:threat
