CVE-2026-4827: Schneider Electric Easergy MiCOM Vulnerabilities — ICS Detection and Remediation

---
title: Potential Schneider Electric MiCOM Device Scanning
id: 8a1c5d22-9e4f-4b3a-8c1d-2e3f4a5b6c7d
status: experimental
description: Detects scanning activity or connection attempts to common Schneider Electric MiCOM management ports (Web, Modbus) from non-internal admin subnets.
references:
 - https://www.cisa.gov/news-events/ics-advisories/icsa-26-169-07
author: Security Arsenal
date: 2026/04/06
tags:
 - attack.initial_access
 - attack.t1190
logsource:
 category: network_connection
 product: zeek
detection:
 selection:
  dst_port:
   - 80
   - 443
   - 502
  response|contains:
   - 'Schneider'
   - 'MiCOM'
 filter:
  src_ip|startswith:
   - '10.'
   - '192.168.'
   - '172.16.'
 condition: selection and not filter
falsepositives:
 - Legitimate engineering workstation access
 - Authorized vulnerability scanning
level: medium
---
title: Excessive Failed Logins to OT Management Interfaces
id: 9b2d6e33-0f5a-5c4b-9d2e-3f4a5b6c7d8e
status: experimental
description: Detects repeated failed authentication attempts to ICS devices, which may indicate brute-force or fuzzing attempts exploiting input validation issues.
references:
 - https://www.cisa.gov/news-events/ics-advisories/icsa-26-169-07
author: Security Arsenal
date: 2026/04/06
tags:
 - attack.brute_force
 - attack.t1110
logsource:
 category: authentication
 product: zeek
detection:
 selection:
  status: 'failure'
  service|contains:
   - 'http'
   - 'modbus'
 timeframe: 5m
 condition: selection | count() > 10
falsepositives:
 - Misconfigured HMIs
 level: high

let OT_Subnets = dynamic(["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"]); // Customize to your OT VLANs
let TargetPorts = dynamic([80, 443, 502, 102, 2048]); // Common ICS/SCADA ports
DeviceNetworkEvents
| where RemotePort in (TargetPorts)
| where ipv4_is_in_range(RemoteIP, OT_Subnets)
| summarize Count = count(), DistinctSources = dcount(LocalIP) by RemoteIP, RemotePort, bin(Timestamp, 15m)
| where Count > 50 // Threshold tuning required based on baseline traffic
| project TimeGenerated, RemoteIP, RemotePort, Count, DistinctSources
| order by Count desc

-- Hunt for established connections to Schneider Electric management ports
SELECT Pid, Name, RemoteAddress, RemotePort, State
FROM listen()
WHERE RemotePort IN (80, 443, 502)
  AND State =~ 'ESTABLISHED'
  AND Name NOT IN ('svchost.exe', 'lsass.exe', 'chrome.exe', 'firefox.exe')

<#
.SYNOPSIS
    Audits Schneider Electric Easergy MiCOM devices for CVE-2026-4827 vulnerability.
.DESCRIPTION
    Compares device firmware versions in a provided CSV against the vulnerable thresholds.
.PARAMETER CsvPath
    Path to the CSV file containing asset inventory. Headers required: DeviceName, Model, FirmwareVersion
.EXAMPLE
    .\Audit-MiCOMDevices.ps1 -CsvPath "C:\Inventory\OT_Assets.csv"
#>

param(
    [Parameter(Mandatory=$true)]
    [string]$CsvPath
)

if (-not (Test-Path $CsvPath)) {
    Write-Error "Inventory file not found: $CsvPath"
    exit 1
}

$inventory = Import-Csv -Path $CsvPath

Write-Host "Starting audit for CVE-2026-4827..." -ForegroundColor Cyan

foreach ($device in $inventory) {
    $vulnerable = $false
    $model = $device.Model.Trim()
    $version = $device.FirmwareVersion.Trim()

    # Normalize version strings for comparison (simplified logic for illustration)
    # In production, use robust version parsing logic

    switch -Wildcard ($model) {
        "*C264*" {
            if ($version -le "D7.33") { $vulnerable = $true }
        }
        "*P139*" {
            if ($version -le "P139.678.700") { $vulnerable = $true }
        }
        "*P437*" {
            # Handling the specific P4 series truncation in the advisory
            if ($version -like "P4*" -and $version -ne "P437.5.3.27") { 
                # Logic: Check if version is strictly older than patched version
                # Assuming patched version is P437.5.3.27 based on standard release patterns
                $vulnerable = $true 
            }
        }
    }

    if ($vulnerable) {
        Write-Host "[VULNERABLE] $($device.DeviceName) | Model: $model | Version: $version" -ForegroundColor Red
    } else {
        Write-Host "[OK] $($device.DeviceName) | Model: $model | Version: $version" -ForegroundColor Green
    }
}