MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Exfiltration |
Rule body
id: 32c460ad-2d40-43e9-8ead-5cdd1d7a3163
name: Cisco WSA - Unexpected uploads
description: |
'Detects unexpected file uploads.'
severity: High
status: Available
requiredDataConnectors:
- connectorId: SyslogAma
datatypes:
- Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- Exfiltration
relevantTechniques:
- T1567
query: |
let f_cnt_upload_threshold = 5;
let f_upload_size_threshold = 5000000;
CiscoWSAEvent
| where HttpRequestMethod in~ ('POST', 'PUT')
| where isnotempty(AmpFileName)
| where UrlCategory in~ ('IW_fts', 'IW_osb')
| where DstBytes > f_upload_size_threshold
| summarize count() by AmpFileName, SrcUserName, bin(TimeGenerated, 10m)
| where count_ >= f_cnt_upload_threshold
| extend AccountCustomEntity = SrcUserName
entityMappings:
- entityType: Account
fieldMappings:
- identifier: Name
columnName: AccountCustomEntity
version: 1.0.3
kind: Scheduled
Stages and Predicates
Parameters
let f_cnt_upload_threshold = 5;
let f_upload_size_threshold = 5000000;
Stage 1: source
CiscoWSAEvent
Stage 2: where
| where HttpRequestMethod in~ ('POST', 'PUT')
Stage 3: where
| where isnotempty(AmpFileName)
Stage 4: where
| where UrlCategory in~ ('IW_fts', 'IW_osb')
Stage 5: where
| where DstBytes > f_upload_size_threshold
Stage 6: summarize
| summarize count() by AmpFileName, SrcUserName, bin(TimeGenerated, 10m)
Stage 7: where
| where count_ >= f_cnt_upload_threshold
Stage 8: extend
| extend AccountCustomEntity = SrcUserName
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
AmpFileName | is_not_null | field:"AmpFileName" kind:is_not_null | |
DstBytes | gt |
| field:"DstBytes" kind:gt value:"5000000" |
HttpRequestMethod | in |
| field:"HttpRequestMethod" kind:in |
UrlCategory | in |
| field:"UrlCategory" kind:in |
count_ | ge |
| field:"count_" kind:ge value:"5" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
AmpFileName | summarize |
SrcUserName | summarize |
AccountCustomEntity | extend |