Detection: Windows Hosts File Access

Updated Date: 2026-03-03 ID: b34bcf35-5380-4b00-b208-5531303fb751 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

This Analytic detects the execution of a process attempting to access the hosts file. The hosts file is a critical file for network configuration and DNS resolution. If an attacker gains access to it, they can redirect traffic to malicious websites, serve fake content or block legitimate security websites.

Search

 1`wineventlog_security`
 2EventCode=4663
 3object_file_path="*:\\Windows\\System32\\drivers\\etc\\hosts"
 4NOT process_path IN (
 5    "*:\\Windows\\explorer.exe",
 6    "*:\\Windows\\System32\\lsass.exe",
 7    "*:\\Windows\\System32\\SearchIndexer.exe",
 8    "*:\\Windows\\System32\\services.exe",
 9    "*:\\Windows\\System32\\svchost.exe",
10    "*:\\Windows\\SysWow64\\SearchIndexer.exe",
11    "*:\\Windows\\SysWow64\\svchost.exe"
12)
13
14| stats count
15    by _time object_file_path object_file_name dest process_name
16       process_path process_id EventCode
17
18| eval process_path = lower(process_path)
19
20| lookup browser_process_and_path browser_process_path as process_path OUTPUT is_valid_browser_path
21
22| eval is_valid_browser_path=coalesce(is_valid_browser_path,"false")
23
24| where is_valid_browser_path = "false"
25
26| `security_content_ctime(firstTime)`
27
28| `security_content_ctime(lastTime)`
29
30| `windows_hosts_file_access_filter`

Data Source

Name	Platform	Sourcetype	Source
Windows Event Log Security 4663	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Security'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_hosts_file_access_filter	`search *`

windows_hosts_file_access_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1012	Query Registry	Discovery

Exploitation

DE.AE

CIS 10

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

To successfully implement this search, you must ingest Windows Security Event logs and track event code 4663. For 4663, enable "Audit Object Access" in Group Policy. Then check the two boxes listed for both "Success" and "Failure." This search may trigger on a browser application that is not included in the browser_app_list lookup file.

Known False Positives

Administrator may access this registry for product key recovery purposes.

Associated Analytic Story

BlankGrabber Stealer

Risk Based Analytics (RBA)

Risk Message:

A [$process_name$] attempting to access the hosts file [$object_file_path$] on [$dest$].

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	20	process_name

References

https://cert.gov.ua/article/6284730

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`

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