Windows Unusual FileZilla XML Config Access

Status: production
Severity: low
Group by: ObjectType, access_mask, computer_name, object_name, process_id, process_name, signature_id, user
Author: Teoderick Contreras, Splunk
Source: github.com/splunk/security_content

The following analytic identifies processes accessing FileZilla XML config files such as recentservers.xml and sitemanager.xml. It leverages Windows Security Event logs, specifically monitoring EventCode 4663, which tracks object access events. This activity is significant because it can indicate unauthorized access or manipulation of sensitive configuration files used by FileZilla, a popular FTP client. If confirmed malicious, this could lead to data exfiltration, credential theft, or further compromise of the system.

Known false positives

a third party application can access the FileZilla XML config files. Filter is needed.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1552.001` Unsecured Credentials: Credentials In Files

Telemetry coverage

Provider	Record / event type
Security-Auditing	Event ID 4663: An attempt was made to access an object.

Rule body

name: Windows Unusual FileZilla XML Config Access
id: 47dc0426-cbe4-4253-8b86-1a983c3f9951
version: 5
creation_date: '2025-07-16'
modification_date: '2026-06-25'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic identifies processes accessing FileZilla XML config files such as recentservers.xml and sitemanager.xml. It leverages Windows Security Event logs, specifically monitoring EventCode 4663, which tracks object access events. This activity is significant because it can indicate unauthorized access or manipulation of sensitive configuration files used by FileZilla, a popular FTP client. If confirmed malicious, this could lead to data exfiltration, credential theft, or further compromise of the system.
data_source:
    - Windows Event Log Security 4663
search: '`wineventlog_security` EventCode=4663  NOT (ProcessName IN("C:\\Program Files\\FileZilla FTP Client\\filezilla.exe", "C:\Program Files (x86)\\FileZilla FTP Client\\filezilla.exe", "C:\\Program Files\\Microsoft OneDrive\\OneDrive.exe", "C:\\Program Files (x86)\\Microsoft OneDrive\\OneDrive.exe")) file_path IN ("*FileZilla\\recentservers.xml*", "*FileZilla\\sitemanager.xml*") | stats count min(_time) as firstTime max(_time) as lastTime by  ObjectName ObjectType ProcessName AccessMask process_id EventCode Computer Caller_User_Name | rename Computer as dest Caller_User_Name as user ProcessName as process_name |  `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_unusual_filezilla_xml_config_access_filter`'
how_to_implement: 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."
known_false_positives: a third party application can access the FileZilla XML config files. Filter is needed.
references:
    - https://www.trendmicro.com/en_us/research/18/k/trickbot-shows-off-new-trick-password-grabber-module.html
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: a non filezilla process $process_name$ with $process_id$ accessed FileZilla XML config files on host $dest$
threat_objects:
    - field: process_name
      type: process_name
analytic_story:
    - Quasar RAT
    - Phantom Stealer
asset_type: Endpoint
mitre_attack_id:
    - T1552.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: `search`

`wineventlog_security` EventCode=4663  NOT (ProcessName IN("C:\\Program Files\\FileZilla FTP Client\\filezilla.exe", "C:\Program Files (x86)\\FileZilla FTP Client\\filezilla.exe", "C:\\Program Files\\Microsoft OneDrive\\OneDrive.exe", "C:\\Program Files (x86)\\Microsoft OneDrive\\OneDrive.exe")) file_path IN ("*FileZilla\\recentservers.xml*", "*FileZilla\\sitemanager.xml*")

Stage 2: `stats`

| stats count min(_time) as firstTime max(_time) as lastTime by  ObjectName ObjectType ProcessName AccessMask process_id EventCode Computer Caller_User_Name

Stage 3: `rename`

| rename Computer as dest Caller_User_Name as user ProcessName as process_name

Stage 4: `search`

| `security_content_ctime(firstTime)`

Stage 5: `search`

| `security_content_ctime(lastTime)`

Stage 6: `search`

| `windows_unusual_filezilla_xml_config_access_filter`

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`ProcessName`	in	`"C:\Program Files (x86)\\FileZilla FTP Client\\filezilla.exe"`, `"C:\\Program Files (x86)\\Microsoft OneDrive\\OneDrive.exe"`, `"C:\\Program Files\\FileZilla FTP Client\\filezilla.exe"`, `"C:\\Program Files\\Microsoft OneDrive\\OneDrive.exe"`	`excludes:ProcessName`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`4663` corpus 35 (splunk 30, kusto 5)	`field:"EventID" kind:eq value:"4663"`
`file_path`	in	`"FileZilla\\recentservers.xml"` `"FileZilla\\sitemanager.xml"`	`field:"TargetFilename" kind:in`