Detection: Cisco Secure Firewall - Malware File Downloaded

Description

The following analytic detects file downloads that were classified as malware by Cisco Secure Firewall Threat Defense. It relies on the SHA_Disposition field with a value of "Malware" and includes metadata such as file name, file_hash hash, and threat classification. This analytic is critical for surfacing file-based threats that are identified via Cisco's AMP or Threat Grid integrations. If confirmed malicious, this could indicate delivery of malware.

 1`cisco_secure_firewall` EventType=FileEvent SHA_Disposition="Malware" FileDirection="Download"
 2
 3| lookup cisco_secure_firewall_filetype_lookup Name as FileType OUTPUT Description
 4
 5| stats count min(_time) as firstTime max(_time) as lastTime
 6        values(uri) as uri
 7        values(ClientApplication) as ClientApplication
 8        values(file_hash) as file_hash
 9        by FileDirection dest src_ip dest_port FileType app file_name ThreatName Description
10
11| `security_content_ctime(firstTime)`
12
13| `security_content_ctime(lastTime)`
14
15| table firstTime lastTime src_ip dest dest_port FileDirection FileType Description uri file_name file_hash app ClientApplication ThreatName SHA_Disposition
16
17| `cisco_secure_firewall___malware_file_downloaded_filter`

Data Source

Name Platform Sourcetype Source
Cisco Secure Firewall Threat Defense File Event N/A 'cisco:sfw:estreamer' 'not_applicable'

Macros Used

Name Value
cisco_secure_firewall sourcetype="cisco:sfw:estreamer"
cisco_secure_firewall___malware_file_downloaded_filter search *
cisco_secure_firewall___malware_file_downloaded_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

This search requires Cisco Secure Firewall Threat Defense Logs, which includes the FileEvent EventType. This search uses an input macro named cisco_secure_firewall. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Cisco Secure Firewall Threat Defense logs. Replace the macro definition with configurations for your Splunk environment. The search also uses a post-filter macro designed to filter out known false positives. The logs are to be ingested using the Splunk Add-on for Cisco Security Cloud (https://splunkbase.splunk.com/app/7404). The malware & file access policy must also enable logging.

Known False Positives

Malicious verdicts could be outdated or incorrect due to retroactive threat intel.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

File with Malware disposition downloaded from $dest$ over port $dest_port$ by $src_ip$

Risk Object Risk Object Type Risk Score Threat Objects
src_ip system 30 file_hash, file_name

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Passing N/A N/A N/A
Unit Passing Dataset not_applicable cisco:sfw:estreamer
Integration ✅ Passing Dataset not_applicable cisco:sfw:estreamer

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range


Source: GitHub | Version: 1