ID | Technique | Tactic |
---|---|---|
T1105 | Ingress Tool Transfer | Command And Control |
T1571 | Non-Standard Port | Command And Control |
Detection: Cisco Secure Firewall - File Download Over Uncommon Port
Description
The following analytic detects file transfers flagged as malware that occurred over non-standard ports (other than 80 and 443). Adversaries may attempt to bypass protocol-based detection or use alternate ports to blend in with other traffic. This analytic identifies these non-conventional flows and surfaces potential evasion techniques. If confirmed malicious this indicate potential malware delivery or other nefarious activity.
Search
1`cisco_secure_firewall` EventType=FileEvent FileDirection="Download" NOT dest_port IN (80, 443)
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(file_name) as file_name
7 values(uri) as uri
8 values(ClientApplication) as ClientApplication
9 values(file_hash) as file_hash
10 values(SHA_Disposition) as SHA_Disposition
11 by FileDirection FileType app ThreatName dest_port Description src_ip dest
12
13| `security_content_ctime(firstTime)`
14
15| `security_content_ctime(lastTime)`
16
17| table firstTime lastTime src_ip dest dest_port FileDirection FileType Description uri ClientApplication file_name file_hash SHA_Disposition ThreatName
18
19| `cisco_secure_firewall___file_download_over_uncommon_port_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___file_download_over_uncommon_port_filter | search * |
cisco_secure_firewall___file_download_over_uncommon_port_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 |
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
Some legitimate applications may download files over custom ports (e.g., CDN mirrors, APIs). Apply additional filters accordingly.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
The host $src_ip$ downloaded a file $file_name$ of type $FileType$ from $dest$ over the uncommon port $dest_port$
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