Remus Stealer & Gamaredon GammaSteel: OTX Pulse Analysis — Credential Theft & RAT Campaigns

---
title: Potential Argamal COM Hijacking Persistence
id: 2628f7a2-6b89-4d1f-9c3e-5b4d7e8f9a0e
status: experimental
description: Detects persistence mechanism used by Argamal malware via COM hijacking of the Windows Color System Calibration Loader.
references:
    - https://otx.alienvault.com/pulse/6266789f8b67460b681b4560/
author: Security Arsenal
date: 2026/06/05
modified: 2026/06/05
tags:
    - attack.persistence
    - attack.t1574.001
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|contains: 'CLSID'
        TargetObject|contains: 'InprocServer32'
        Details|contains: 'dll'
    filter_legit:
        Details|contains: 'C:\\Windows\\System32\\'
    condition: selection and not filter_legit
falsepositives:
    - Legitimate software installation altering COM components
level: high
---
title: Gamaredon GammaSteel Registry Persistence
id: 3e7f1a2b-8c6d-4e9f-9a0b-1c2d3e4f5a6b
status: experimental
description: Detects Gamaredon Group GammaSteel malware storing payload functions in the HKCU\Printers registry key.
references:
    - https://otx.alienvault.com/pulse/6266789f8b67460b681b4561/
author: Security Arsenal
date: 2026/06/05
modified: 2026/06/05
tags:
    - attack.persistence
    - attack.t1114.001
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|contains: 'Software\\Microsoft\\Windows NT\\CurrentVersion\\Printers\\'
        Details|re: '[a-zA-Z0-9]{100,}'
    condition: selection
falsepositives:
    - Legitimate printer driver installations
level: high
---
title: Remus Stealer Browser Credential Theft
id: 4f8b2c3d-9d7e-5f0a-0b1c-2d3e4f5a6b7c
status: experimental
description: Detects suspicious processes attempting to access browser Login Data or Local State files, indicative of credential theft like Remus Stealer bypassing Application-Bound Encryption.
references:
    - https://otx.alienvault.com/pulse/6266789f8b67460b681b4562/
author: Security Arsenal
date: 2026/06/05
modified: 2026/06/05
tags:
    - attack.credential_access
    - attack.t1555.003
logsource:
    product: windows
    category: file_access
detection:
    selection:
        TargetFilename|contains:
            - '\\AppData\\Local\\Google\\Chrome\\User Data\\Default\\Login Data'
            - '\\AppData\\Local\\Google\\Chrome\\User Data\\Local State'
            - '\\AppData\\Local\\Microsoft\\Edge\\User Data\\Default\\Login Data'
            - '\\AppData\\Local\\Microsoft\\Edge\\User Data\\Local State'
    filter_browser:
        Image|endswith:
            - '\\chrome.exe'
            - '\\msedge.exe'
    condition: selection and not filter_browser
falsepositives:
    - Legitimate backup utilities or password managers
level: medium


kql
// Hunt for GammaSteel Registry Artifacts
DeviceRegistryEvents
| where RegistryKey contains @"Software\Microsoft\Windows NT\CurrentVersion\Printers"
| where ActionType == "RegistryValueSet"
| project Timestamp, DeviceName, RegistryKey, RegistryValueName, RegistryValueData, InitiatingProcessFileName, InitiatingProcessAccountName
| order by Timestamp desc

// Hunt for Argamal C2 Network Connections
DeviceNetworkEvents
| where RemotePort in (80, 443, 8080)
| where RemoteIP has_any ("194.150.220.218", "217.156.122.75", "165.22.170.129")
   or RemoteUrl has_any ("asper1.freeddns.org", "guiformat.com", "forestoaker.com", "arch2.maxdatahost1.cyou")
| project Timestamp, DeviceName, RemoteIP, RemoteUrl, RemotePort, InitiatingProcessFileName, InitiatingProcessCommandLine
| order by Timestamp desc

// Hunt for CloudZ RAT File Execution (Based on IOCs)
DeviceFileEvents
| where SHA256 has_any (
    "5b7284bcf30569ae400e416a62391720cc9081e6047f15816f9d1a04a06eb321",
    "24398b75be2645e6c695e529e62e60deb418143a4bbea13c561d3c361419eb54",
    "33af554562176eff34598a839051b8e91692b0305edfdbb4d8eb9df0103ffd98",
    "65fcd965040fabeb6f092df0a4b6856125018bb3b6a1876342da458139f77dac",
    "ed5de036edbbda52ab0049d2163607038d38a49404a46b6bcfc4bac26b743832"
)
| project Timestamp, DeviceName, FileName, FolderPath, SHA256, InitiatingProcessFileName
| order by Timestamp desc


powershell
# IOC Hunt Script for GammaSteel and Argamal Artifacts
# Requires Administrator Privileges

Write-Host "[*] Starting IOC Hunt for GammaSteel and Argamal..." -ForegroundColor Cyan

# 1. Check for GammaSteel Registry Persistence (HKCU\Printers)
Write-Host "[+] Checking HKCU\Printers for suspicious values..." -ForegroundColor Yellow
try {
    $printerKeys = Get-ChildItem "HKCU:\Software\Microsoft\Windows NT\CurrentVersion\Printers" -Recurse -ErrorAction Stop
    foreach ($key in $printerKeys) {
        $values = Get-ItemProperty $key.PSPath -ErrorAction SilentlyContinue
        foreach ($prop in $values.PSObject.Properties) {
            if ($prop.Name -ne "PSPath" -and $prop.Name -ne "PSParentPath" -and $prop.Name -ne "PSChildName") {
                # Check for long binary strings typical of payloads
                if ($prop.Value -is [string] -and $prop.Value.Length -gt 50) {
                    Write-Host "ALERT: Suspicious value found in $($key.Name)\$($prop.Name)" -ForegroundColor Red
                    Write-Host "Value: $($prop.Value.Substring(0, [Math]::Min(50, $prop.Value.Length)))..." -ForegroundColor DarkRed
                }
            }
        }
    }
} catch {
    Write-Host "No Printers key found or access denied." -ForegroundColor Gray
}

# 2. Check for Argamal COM Hijacking (Windows Color System)
Write-Host "[+] Checking for COM Hijacking in Windows Color System..." -ForegroundColor Yellow
# Search for InprocServer32 modifications under MSCMS related keys
try {
    Get-ChildItem "HKCR:\CLSID" -Recurse -ErrorAction Stop | Where-Object {
        $_.GetSubKeyNames() -contains "InprocServer32"
    } | ForEach-Object {
        $clsidPath = $_.PSPath
        $inprocPath = Join-Path $clsidPath "InprocServer32"
        
        # Check default value
        $defaultVal = (Get-ItemProperty $inprocPath -ErrorAction SilentlyContinue)."(default)"
        
        # Generic check for non-system32 dlls in calibration related CLSIDs or suspicious paths
        if ($defaultVal -match "dll" -and $defaultVal -notmatch "System32" -and $defaultVal -notmatch "SysWOW64") {
             Write-Host "ALERT: Potential COM Hijacking at $inprocPath" -ForegroundColor Red
             Write-Host "Value: $defaultVal" -ForegroundColor Red
        }
    }
} catch {
    Write-Host "Error scanning CLSIDs." -ForegroundColor Gray
}

Write-Host "[*] Hunt complete." -ForegroundColor Green