Detection rules › Sigma
Suspicious CrushFTP Child Process
Detects suspicious child processes spawned by the CrushFTP service that may indicate exploitation of remote code execution vulnerabilities such as CVE-2025-31161, where attackers can achieve RCE through crafted HTTP requests. The detection focuses on commonly abused Windows executables (like powershell.exe, cmd.exe etc.) that attackers typically use post-exploitation to execute malicious commands.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1190 Exploit Public-Facing Application |
| Execution | T1059.001 Command and Scripting Interpreter: PowerShell, T1059.003 Command and Scripting Interpreter: Windows Command Shell |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
title: Suspicious CrushFTP Child Process
id: 459628e3-1b00-4e9b-9e5b-7da8961aea35
status: experimental
description: |
Detects suspicious child processes spawned by the CrushFTP service that may indicate exploitation of remote code execution vulnerabilities such as
CVE-2025-31161, where attackers can achieve RCE through crafted HTTP requests.
The detection focuses on commonly abused Windows executables (like powershell.exe, cmd.exe etc.) that attackers typically use post-exploitation to execute malicious commands.
references:
- https://nvd.nist.gov/vuln/detail/CVE-2025-2825
- https://www.crushftp.com/crush11wiki/Wiki.jsp?page=Update
- https://outpost24.com/blog/crushftp-auth-bypass-vulnerability/
- https://attackerkb.com/topics/k0EgiL9Psz/cve-2025-2825/rapid7-analysis
- https://projectdiscovery.io/blog/crushftp-authentication-bypass
author: Craig Sweeney, Matt Anderson, Jose Oregon, Tim Kasper, Faith Stratton, Samantha Shaw, Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-04-10
tags:
- attack.initial-access
- attack.execution
- attack.t1059.001
- attack.t1059.003
- attack.t1190
- cve.2025-31161
- detection.emerging-threats
logsource:
category: process_creation
product: windows
detection:
selection_parent:
ParentImage|endswith: '\crushftpservice.exe'
selection_child:
Image|endswith:
- '\bash.exe'
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell.exe'
- '\powershell_ise.exe'
- '\pwsh.exe'
- '\sh.exe'
- '\wscript.exe'
condition: all of selection_*
falsepositives:
- Legitimate CrushFTP administrative actions
- Software updates
level: medium
Stages and Predicates
Stage 0: condition
all of selection_*Stage 1: selection_parent
selection_parent:
ParentImage|endswith: '\crushftpservice.exe'
Stage 2: selection_child
selection_child:
Image|endswith:
- '\bash.exe'
- '\cmd.exe'
- '\cscript.exe'
- '\mshta.exe'
- '\powershell.exe'
- '\powershell_ise.exe'
- '\pwsh.exe'
- '\sh.exe'
- '\wscript.exe'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Image | ends_with |
|
ParentImage | ends_with |
|