Detect Cloud Storage Object Discovery in Sumo Logic CSE
This detection identifies adversary enumeration of cloud storage objects across AWS S3, Azure Blob Storage, and GCP Cloud Storage. Attackers use native cloud APIs (e.g., ListObjectsV2 for S3, List Blobs for Azure) to survey accessible buckets and containers, typically as a precursor to data staging or exfiltration. The detection looks for anomalous listing activity including high-volume object enumeration, access from unexpected identities or IPs, enumeration across multiple buckets in short time windows, and listing operations performed by service principals or IAM roles outside their expected behavioral baseline. Tools such as Pacu and Peirates are known to automate these enumeration workflows.
MITRE ATT&CK
- Tactic
- Discovery
- Technique
- T1619 Cloud Storage Object Discovery
- Canonical reference
- https://attack.mitre.org/techniques/T1619/
Sumo Detection Query
_sourceCategory=aws/cloudtrail OR _sourceCategory=azure/storage | json auto | where event_name in ("ListObjectsV2", "ListObjects", "ListBuckets", "GetBucketAcl", "GetBucketPolicy") or operation_name matches "*blobs/read*" | if(event_name = "ListBuckets" or event_name = "ListAllMyBuckets", "High", if(count > 100, "High", "Medium")) as RiskLevel | stats count by user_identity_arn, src_ip_addr, event_name, aws_region, RiskLevel | sort by count descSumo Logic query for T1619 detection using source category filters and aggregation. Detects high-volume or broad cloud storage enumeration across AWS S3 (via CloudTrail ListObjectsV2/L
Data Sources
Required Tables
False Positives & Tuning
- Legitimate cloud-native backup solutions (e.g., Veeam, AWS Backup, Azure Backup) that enumerate storage objects on a schedule
- Data lake or ETL pipeline services (Azure Data Factory, AWS Glue) that list objects as part of normal pipeline execution
- Security posture management tools (Prisma Cloud, Wiz, AWS Security Hub) performing periodic storage inventory scans
- DevOps CI/CD pipelines that sync or audit S3/Blob content as part of deployment workflows
- Cloud cost optimization tools (CloudHealth, Spot.io) enumerating storage for billing analysis
Other platforms for T1619
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1AWS S3 Bucket and Object Enumeration with AWS CLI
Expected signal: CloudTrail will generate events: eventName=ListBuckets, eventName=ListObjectsV2 (one per bucket enumerated), eventName=GetBucketLocation, eventName=GetBucketAcl, eventName=GetBucketPolicy. All events will share the same userIdentity.arn and originating sourceIPAddress. Events appear in CloudTrail within 15 minutes (standard delivery) or near-real-time (CloudTrail Lake).
- Test 2Pacu Framework AWS Storage Enumeration Module
Expected signal: CloudTrail events with userAgent containing 'Boto3' (Pacu uses Boto3 SDK). EventNames: ListBuckets, GetBucketAcl, GetBucketLocation, DescribeVolumes, DescribeSnapshots. The Pacu session generates many rapid sequential API calls detectable by rate and ordering patterns.
- Test 3Azure Blob Storage Container and Object Enumeration via Azure CLI
Expected signal: Azure StorageBlobLogs table will contain OperationName values: ListContainers, ListBlobs, GetContainerProperties. CallerIpAddress will reflect the test machine IP. AuthenticationType will show 'StorageKey' (when using account key) or 'OAuth' (when using service principal). AzureActivity log will show Microsoft.Storage/storageAccounts/listKeys/action if keys were retrieved.
References (7)
- https://attack.mitre.org/techniques/T1619/
- https://docs.aws.amazon.com/AmazonS3/latest/API/API_ListObjectsV2.html
- https://learn.microsoft.com/en-us/rest/api/storageservices/list-blobs
- https://github.com/RhinoSecurityLabs/pacu
- https://github.com/inguardians/peirates
- https://docs.aws.amazon.com/awscloudtrail/latest/userguide/logging-data-events-with-cloudtrail.html
- https://learn.microsoft.com/en-us/azure/storage/blobs/monitor-blob-storage
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