Data Transfer Size Limits T1030
Tactic: Exfiltration
An adversary may exfiltrate data in fixed size chunks instead of whole files or limit packet sizes below certain thresholds. This approach may be used to avoid triggering network data transfer threshold alerts.
Events covered
6 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
| ESF | exec | Process Execution (Notify) |
| Linux-Auditd | Event ID 1300 | SYSCALL |
| 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 26 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 (55 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 (165 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 (70 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 2 rules
Elastic 2 rules
- GenAI Process Performing Encoding/Chunking Prior to Network Activity
- Potential Data Splitting Detected
Splunk 6 rules
- Linux Auditd Data Transfer Size Limits Via Split
- Linux Auditd Data Transfer Size Limits Via Split Syscall
- MacOS Data Chunking
- Rclone Execution (PowerShell)
- Rclone Execution (Sysmon)
- Rclone Execution (Windows Event Log)
Kusto 16 rules
- Anomaly found in Network Session Traffic (ASIM Network Session schema)
- Cisco SEG - DLP policy violation
- Cisco SEG - Multiple large emails sent to external recipient
- CloudNGFW By Palo Alto Networks - Threat signatures from Unusual IP addresses
- Corelight - Multiple files sent over HTTP with abnormal requests
- Detect unauthorized data transfers using timeseries anomaly (ASIM Web Session)
- Mimecast Data Leak Prevention - Hold
- Mimecast Data Leak Prevention - Hold
- Mimecast Data Leak Prevention - Notifications
- Mimecast Data Leak Prevention - Notifications
- Palo Alto Threat signatures from Unusual IP addresses
- SharePointFileOperation via devices with previously unseen user agents
- SharePointFileOperation via previously unseen IPs
- Threat Essentials - Time series anomaly for data size transferred to public internet
- Time series anomaly detection for total volume of traffic
- Time series anomaly for data size transferred to public internet