Detection rules › Panther

Dropbox Many Downloads

Status
Experimental
Severity
medium
Group by
actor.user.email
Log types
Dropbox.TeamEvent
Tags
Dropbox, Exfiltration
Reference
https://learn.dropbox.com/video-library/upload-and-download-files
Source
github.com/panther-labs/panther-analysis

Detects when a Dropbox user downloads more than 10 distinct files within 60 minutes. This may indicate data exfiltration or unauthorized bulk access to team files. The threshold should be tuned to your environment.

MITRE ATT&CK coverage

TacticTechniques
ExfiltrationT1567 Exfiltration Over Web Service

Rule body yaml

AnalysisType: rule
Filename: dropbox_many_downloads.py
RuleID: "Dropbox.BulkDownloads"
DisplayName: "Dropbox Many Downloads"
Status: Experimental
Enabled: false
Severity: Medium
DedupPeriodMinutes: 60
Threshold: 11
LogTypes:
  - Dropbox.TeamEvent
Description: >
  Detects when a Dropbox user downloads more than 10 distinct files within 60 minutes.
  This may indicate data exfiltration or unauthorized bulk access to team files.
  The threshold should be tuned to your environment.
Reference: https://learn.dropbox.com/video-library/upload-and-download-files
Reports:
  MITRE ATT&CK:
    - TA0010:T1567
Tags:
  - Dropbox
  - Exfiltration
Runbook: |
  1. Query Dropbox.TeamEvent for all file_download events by actor:user:email in the 2 hours around this alert to identify the full list of assets[0]:path:contextual values downloaded
  2. Check involve_non_team_member and the origin:geo_location:ip_address to determine if the downloads originated from an external user or an unexpected location
  3. Search for other suspicious activity by this user in the past 24 hours, including external sharing events, ownership transfers, or logins from new devices or locations
Tests:
  - Name: File Downloaded
    ExpectedResult: true
    Log:
      actor:
        user:
          email: alice@company.com
          _tag: team_member
      event_type:
        _tag: file_download
      assets:
        - path:
            contextual: /alice/report.pdf
      involve_non_team_member: false
      origin:
        geo_location:
          ip_address: 1.2.3.4
  - Name: File Downloaded - Non-Team Member Involved
    ExpectedResult: true
    Log:
      actor:
        user:
          email: alice@company.com
          _tag: team_member
      event_type:
        _tag: file_download
      assets:
        - path:
            contextual: /shared/contract.docx
      involve_non_team_member: true
      origin:
        geo_location:
          ip_address: 5.6.7.8
  - Name: Non-Download Event
    ExpectedResult: false
    Log:
      actor:
        user:
          email: alice@company.com
          _tag: team_member
      event_type:
        _tag: file_view
      assets:
        - path:
            contextual: /alice/report.pdf
      involve_non_team_member: false

Detection logic

Condition

event_type._tag eq "file_download"

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
event_type._tageq
  • file_download

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
useractor.user.email
involve_non_team_member
ip_addressorigin.geo_location.ip_address