JDownloader Supply Chain Compromise (Python RAT) & CVE-2026-41940 Defense

---
title: Suspicious Python Spawn by JDownloader
id: 9a1b2c3d-4e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects JDownloader installers or executables spawning python.exe or pythonw.exe, indicative of the supply chain Python RAT.
references:
 - https://securityaffairs.com/192278/security/security-affairs-malware-newsletter-round-97.html
author: Security Arsenal
date: 2026/04/20
tags:
 - attack.execution
 - attack.t1059.006
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    ParentImage|contains:
      - 'JDownloader'
    Image|endswith:
      - '\python.exe'
      - '\pythonw.exe'
  condition: selection
falsepositives:
  - Legitimate scripting by administrators using JDownloader plugins (rare)
level: critical
---
title: Python RAT Network Connection
id: 1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects python.exe establishing network connections, typical of Python RAT C2 beacons.
references:
 - https://securityaffairs.com/192278/security/security-affairs-malware-newsletter-round-97.html
author: Security Arsenal
date: 2026/04/20
tags:
 - attack.command_and_control
 - attack.t1071
logsource:
  category: network_connection
  product: windows
detection:
  selection:
    Image|endswith:
      - '\python.exe'
      - '\pythonw.exe'
    Initiated: true
  filter:
    DestinationPort:
      - 80
      - 443
      - 8080
  condition: selection and not filter
falsepositives:
  - Legitimate Python development or web server activity
level: high

// Hunt for JDownloader spawning Python processes
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName has "JDownloader"
| where FileName has "python"
| project Timestamp, DeviceName, AccountName, InitiatingProcessCommandLine, FileName, ProcessCommandLine, SHA1, SHA256
// Hunt for unauthorized Python network traffic (C2 beacons)
| union DeviceNetworkEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName has "python"
| where RemotePort !in (80, 443, 8080)
| summarize count() by DeviceName, InitiatingProcessCommandLine, RemoteIP, RemotePort

-- Hunt for suspicious Python processes and scripts in JDownloader directories
SELECT Pid, Name, CommandLine, Exe
FROM pslist()
WHERE Name =~ 'python'
   AND Exe =~ 'JDownloader'

-- Check for Python scripts in JDownloader AppData paths
SELECT FullPath, Size, Mtime
FROM glob(globs='C:/Users/*/AppData/Local/JDownloader/**/*.py')

<#
.SYNOPSIS
    Detects and terminates suspicious Python RAT processes related to JDownloader.
.DESCRIPTION
    Scans for python.exe processes parented by JDownloader and kills the process tree.
#>

function Invoke-JDownloaderCleanse {
    Write-Host "[INFO] Scanning for JDownloader parented Python processes..."
    
    $suspiciousProcs = Get-WmiObject Win32_Process | Where-Object { 
        $_.Name -match 'python.*\.exe' -and 
        (Get-Process -Id $_.ParentProcessId -ErrorAction SilentlyContinue).ProcessName -match 'JDownloader'
    }

    if ($suspiciousProcs) {
        Write-Host "[ALERT] Suspicious Python RAT activity detected. Terminating processes..." -ForegroundColor Red
        foreach ($proc in $suspiciousProcs) {
            try {
                Stop-Process -Id $proc.ProcessId -Force -ErrorAction Stop
                Write-Host "[KILLED] Process ID $($proc.ProcessId) - $($proc.CommandLine)"
            }
            catch {
                Write-Host "[ERROR] Failed to kill process ID $($proc.ProcessId): $_" -ForegroundColor Yellow
            }
        }
        # Optional: Block Hash if known (Replace HASH_PLACEHOLDER with actual IOC)
        # Add-MpPreference -ThreatIDDefaultAction_Ids HASH_PLACEHOLDER -Force
    }
    else {
        Write-Host "[INFO] No suspicious JDownloader/Python activity found."
    }
}

Invoke-JDownloaderCleanse