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Description

The following analytic identifies attempts to download viruses that were blocked by Zscaler within a network. It leverages web proxy logs to detect blocked actions indicative of virus download attempts. Key data points such as device owner, user, URL category, destination URL, and IP are analyzed. This activity is significant as it helps in early detection and remediation of potential virus threats, enhancing network security. If confirmed malicious, this activity could indicate an attempt to compromise the network, potentially leading to data breaches or further malware infections.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-17
  • Author: Gowthamaraj Rajendran, Rod Soto, Splunk
  • ID: aa19e627-d448-4a31-85cd-82068dec5691

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


1
2
3
4
5



`zscaler_proxy` action=blocked threatname!="None" threatclass=Virus 
| stats count min(_time) as firstTime max(_time) as lastTime by action deviceowner user urlcategory url src dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `zscaler_virus_download_threat_blocked_filter`

Macros

The SPL above uses the following Macros:

:information_source: zscaler_virus_download_threat_blocked_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • action
  • threatname
  • deviceowner
  • user
  • urlcategory
  • url
  • dest
  • dest_ip
  • action

How To Implement

You must install the latest version of Zscaler Add-on from Splunkbase. You must be ingesting Zscaler events into your Splunk environment through an ingester. This analytic was written to be used with the "zscalernss-web" sourcetype leveraging the Zscaler proxy data. This enables the integration with Splunk Enterprise Security. Security teams are encouraged to adjust the detection parameters, ensuring the detection is tailored to their specific environment.

Known False Positives

False positives are limited to Zscaler configuration.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
40.0 50 80 Potential Virus Download Threat from dest -[$dest$] on $src$ for user-[$user$].

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 2