Exfiltration Over Web Service: Exfiltration to Cloud Storage T1567.002
Tactic: Exfiltration
Adversaries may exfiltrate data to a cloud storage service rather than over their primary command and control channel. Cloud storage services allow for the storage, edit, and retrieval of data from a remote cloud storage server over the Internet.
Events covered
8 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Sysmon | Event ID 3 | Network connection |
| Sysmon | Event ID 11 | FileCreate |
| Sysmon | Event ID 22 | DNSEvent (DNS query) |
| Security-Auditing | Event ID 4688 | A new process has been created. |
| DNS-Client | Event ID 3008 | DNS query is completed for the name QueryName, type QueryType, query options QueryOptions with status QueryStatus Results QueryResults. |
| PowerShell | Event ID 4103 | Payload Context: ContextInfo User Data: UserData. |
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Authoring guide
Patterns shared across the 43 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (54 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (892 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (124 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 14 rules
- APT40 Dropbox Tool User Agent
- DNS Query for Anonfiles.com Domain - DNS Client
- DNS Query for Anonfiles.com Domain - Sysmon
- DNS Query To MEGA Hosting Website
- DNS Query To MEGA Hosting Website - DNS Client
- DNS Query To Ufile.io
- DNS Query To Ufile.io - DNS Client
- macOS Cloud Storage Access Tools
- Network Connection Initiated To Mega.nz
- PUA - Rclone Execution
- PUA - Restic Backup Tool Execution
- Rclone Activity via Proxy
- Rclone Config File Creation
- Suspicious Dropbox API Usage
Elastic 13 rules
- AWS API Activity from Uncommon S3 Client by Rare User
- AWS DynamoDB Table Exported to S3
- AWS EC2 Export Task
- AWS RDS Snapshot Export
- AWS S3 Bucket Replicated to Another Account
- Azure Storage Blob Retrieval via AzCopy
- Connection to Commonly Abused Web Services
- DNS to Commonly Abused Web Services
- M365 Purview DLP Signal
- Potential Data Exfiltration via Rclone
- Potential PowerShell HackTool Script by Function Names
- Suspicious AWS S3 Connection via Script Interpreter
- Unusual Network Connection to Suspicious Web Service
Splunk 9 rules
- Cisco NVM - Rclone Execution With Network Activity
- Cisco Secure Firewall - Connection to File Sharing Domain
- Cisco Secure Firewall - Potential Data Exfiltration
- Gsuite Drive Share In External Email
- Rclone Execution (PowerShell)
- Rclone Execution (Sysmon)
- Rclone Execution (Windows Event Log)
- Windows Azure Storage Utility Execution Via CLI
- Windows OneDrive Share Mounted via Net
Kusto 5 rules
- CreepyDrive request URL sequence
- CreepyDrive URLs
- GCP Audit Logs - Storage Bucket Made Public
- Powershell Empire Cmdlets Executed in Command Line
- SlackAudit - Public link created for file which can contain sensitive information.