# Exploit Title: Fluentd TD-agent plugin 4.0.1 - Insecure Folder Permission
# Date: 21.12.2020
# Exploit Author: Adrian Bondocea
# Vendor Homepage:
# Software Link:
# Version: <v4.0.1
# Tested on: Windows 10 x64
# CVE : CVE-2020-28169
# External URL:

The td-agent-builder plugin before 2020-12-18 for Fluentd allows attackers to gain privileges because the bin directory is writable by a user account, but a file in bin is executed as NT AUTHORITY\SYSTEM.

Vulnerable Path: ( Authenticated Users have permission to write within the location )
PS C:\opt\td-agent\bin> icacls C:\opt\td-agent\bin
C:\opt\td-agent\bin BUILTIN\Administrators:(I)(OI)(CI)(F)
                    NT AUTHORITY\SYSTEM:(I)(OI)(CI)(F)
                    NT AUTHORITY\Authenticated Users:(I)(M)
                    NT AUTHORITY\Authenticated Users:(I)(OI)(CI)(IO)(M)

Successfully processed 1 files; Failed processing 0 files

Vulnerable service:
PS C:\opt\td-agent\bin> get-service fluentdwinsvc

Status   Name               DisplayName
------   ----               -----------
Running  fluentdwinsvc      Fluentd Windows Service

Service Path:
"C:/opt/td-agent/bin/ruby.exe" -C t"C:/opt/td-agent/lib/ruby/gems/2.7.0/gems/fluentd-1.11.2/lib/fluent/command/.."
 winsvc.rb --service-name fluentdwinsvc