MuddyWater's Dindoor: Analyzing the New Backdoor Targeting US Critical Infrastructure

Good catch on the KQL query. I'd also recommend checking for the specific registry persistence mechanisms they often favor alongside Dindoor. They frequently use run keys or custom scheduled tasks. You can automate a check on endpoints with this snippet:

Get-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Run' | 
Where-Object { $_.PSObject.Properties.Name -match 'Update' -and $_.PSObject.Properties.Value -match 'powershell' }


If you see vague keys named 'Update' or 'Config' pointing to PowerShell, flag it immediately.

We saw similar behavior last month but attributed it to a different Iran-based group. The key for us was analyzing the user-agent strings in the proxy logs. Dindoor often tries to mimic standard Windows updates or browser traffic. If you aren't decrypting outbound SSL/TLS on your proxy, you might miss the C2 callbacks entirely.

Is anyone else having trouble getting management to care about this? Since it's 'just' a backdoor and not ransomware, the prioritization is low here. I'm trying to explain that the exfiltration risk for banks and airports is massive, but without a flashy encryption event, it's an uphill battle.

Building on the proxy angle, definitely check for 'SSL certificate verify failed' alerts in your proxy logs. MuddyWater’s C2 infrastructure often uses self-signed certs. If your environment allows, look for high-entropy URL patterns which might indicate encoded commands.

grep -i "certificate\|untrusted" /var/log/proxy/access.log | awk '{print $1}' | sort -u

Correlating these IPs against known C2 lists usually uncovers the command channel faster than relying on just signatures.

Building on the PowerShell mentions, ensure Script Block Logging is enabled across the fleet. MuddyWater relies heavily on obfuscation, and this is often the only way to catch the payload logic before it vanishes from memory. You can enforce it quickly via:

Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" -Name "EnableScriptBlockLogging" -Value 1

Also, watch for powershell.exe spawning from winword.exe; they still love macro-laced documents for delivery.

Great points so far. Beyond the standard persistence mechanisms, MuddyWater also frequently abuses bitsadmin for C2 communication to blend in with Windows update traffic. While Script Block Logging catches the payload, checking for active BITS jobs is crucial for spotting the connection if they try to bypass proxy checks. You can enumerate suspicious jobs on a host using:

cmd bitsadmin /list /allusers /verbose

Building on the endpoint discussion, pay close attention to the execution chain. Dindoor typically executes via rundll32.exe spawned from a PowerShell script. Watch for rundll32 instances with obfuscated arguments or specific ordinals that don't match standard OS behavior. You can hunt for this parent-child relationship with a simple query:

DeviceProcessEvents
| where InitiatingProcessFileName == "powershell.exe"
| where FileName == "rundll32.exe"
| where ProcessCommandLine has "javascript:" or ProcessCommandLine has ".dll"

Great points on persistence and logging. I'd add that you should specifically hunt for WMI Event Consumers. MuddyWater often leverages this for fileless persistence alongside their other methods. You can enumerate active event filters to spot anomalies quickly. Look for recently created filters pointing to suspicious scripts or executables.

Get-WmiObject -Namespace root\subscription -Class __EventFilter | Select-Object Name, Query, __PATH

This usually catches the lateral movement triggers before they fully deploy across the environment.