Defending Against Novel C2 and AI Token Theft: Analysis of Security Affairs Round 100

The release of the 100th edition of the Security Affairs malicious software newsletter marks a critical moment for defenders, highlighting a distinct evolution in attacker tradecraft. The threats covered in this round are not merely volumetric; they are technically diverse, signaling a shift toward "living-off-the-land" in communication channels (abusing Steam Community profiles) and a high-value target shift toward AI infrastructure (stealing API tokens via fake Codex interfaces).

Additionally, the reporting on Operation Dragon Weave underscores the persistence of China-linked espionage against diplomatic and governmental entities in the Czech Republic and Taiwan. For Security Arsenal clients and the broader security community, this bulletin demands an immediate review of detection logic regarding unexpected web traffic to legitimate platforms and the protection of emerging AI assets.

Technical Analysis

Based on the intelligence summarized in Round 100, we are tracking three distinct vectors of compromise:

1. Steam Community Profiles as C2 Infrastructure

Threat actors are increasingly abusing trusted, high-reputation domains to bypass network egress controls. In this specific campaign, malicious software utilizes Steam Community Profiles for Command & Control (C2) operations.

Mechanism: The malware likely parses public user profile data, "About" sections, or comment walls on steamcommunity.com to retrieve encoded instructions from the attacker. This makes blocking the C2 domain difficult without disrupting legitimate gaming traffic or user access to Steam.
Risk: Standard IP-based blocklists and domain categorization often fail here. Connections to steamcommunity.com from non-gaming endpoints (e.g., servers or developer workstations) are anomalous but might be allowed by default firewall policies.

2. "Codex" Remote UI and AI Token Theft

A campaign involving a "Legitimate-Looking Codex Remote UI" is actively targeting developers and engineers to steal AI API tokens.

Mechanism: The malware mimics a legitimate remote UI interface, likely distributed via phishing or malicious repository cloning. Once executed, it scours the file system for configuration files associated with AI services (e.g., OpenAI, Anthropic). Common targets include .config directories, environment files (.env), and credential management stores where API keys are stored for automation.
Impact: Compromise of AI tokens allows attackers to consume quotas, access proprietary Large Language Model (LLM) prompts, and exfiltrate data fed into AI models.

3. Operation Dragon Weave

This China-linked campaign focuses on geopolitical targeting (Czech Republic and Taiwan).

Mechanism: While specific TTPs vary by target, these campaigns typically utilize spear-phishing with weaponized documents or archives to deliver custom backdoors. The objective is long-term persistence and data exfiltration.
Relevance: Even organizations outside these regions should analyze the specific infrastructure or malware signatures if released, as these tools often eventually repurpose for broader cybercrime operations.

Detection & Response

To address these specific threats, we have developed the following detection rules and hunt queries.

SIGMA Rules

YAML

---
title: Potential Steam Community C2 Activity
id: 9f2e1a8c-4d3b-4a5f-9b1c-2d3e4f5a6b7c
status: experimental
description: Detects non-browser processes establishing connections to Steam Community domains, potential C2 activity.
references:
  - https://securityaffairs.com/193268/malware/security-affairs-malware-newsletter-round-100.html
author: Security Arsenal
date: 2026/04/06
tags:
  - attack.command_and_control
  - attack.t1071.001
logsource:
  category: network_connection
  product: windows
detection:
  selection:
    DestinationHostname|contains:
      - 'steamcommunity.com'
  filter_legit_steam:
    Image|contains:
      - '\steam.exe'
      - '\steamwebhelper.exe'
      - '\steam_service.exe'
  filter_browsers:
    Image|contains:
      - '\chrome.exe'
      - '\msedge.exe'
      - '\firefox.exe'
  condition: selection and not 1 of filter*
falsepositives:
  - Legitimate Steam clients launched directly
  - Third-party game launchers utilizing Steam APIs
level: high
---
title: Suspicious Access to AI Configuration Files
id: b1c2d3e4-5f6a-7b8c-9d0e-1f2a3b4c5d6e
status: experimental
description: Detects processes accessing common AI token storage locations (OpenAI/Claude) other than authorized terminals.
references:
  - https://securityaffairs.com/193268/malware/security-affairs-malware-newsletter-round-100.html
author: Security Arsenal
date: 2026/04/06
tags:
  - attack.credential_access
  - attack.t1552.001
logsource:
  category: file_access
  product: windows
detection:
  selection:
    TargetFilename|contains:
      - '\.config\openai'
      - '\.config\claude'
      - '\.anthropic'
      - '\.env'
  filter_legit:
    Image|contains:
      - '\WindowsTerminal.exe'
      - '\code.exe'
      - '\explorer.exe'
  condition: selection and not filter_legit
falsepositives:
  - Developers manually inspecting config files
level: medium

KQL (Microsoft Sentinel)

KQL — Microsoft Sentinel / Defender

// Hunt for Non-Steam Processes Connecting to Steam Community
DeviceNetworkEvents
| where RemoteUrl contains "steamcommunity.com"
| where not InitiatingProcessFileName in ("steam.exe", "steamwebhelper.exe", "chrome.exe", "msedge.exe", "firefox.exe")
| project Timestamp, DeviceName, InitiatingProcessFileName, InitiatingProcessCommandLine, RemoteUrl, RemotePort
| order by Timestamp desc

// Hunt for AI Config File Access
DeviceFileEvents
| where FileName in ("api_key", "config.", "claude_desktop_config.") or FolderPath contains "openai"
| where InitiatingProcessFileName !in ("WindowsTerminal.exe", "Code.exe", "explorer.exe")
| project Timestamp, DeviceName, ActionType, InitiatingProcessFileName, FileName, FolderPath
| order by Timestamp desc

Velociraptor VQL

VQL — Velociraptor

-- Hunt for processes connecting to Steam Community (Linux/Mac/Windows)
SELECT Pid, Name, Exe, CommandLine, remote_address, remote_port
FROM listen_sock()
WHERE remote_address =~ 'steamcommunity.com'
  AND Name NOT IN ('steam', 'steamwebhelper', 'chrome', 'firefox', 'msedge')

-- Hunt for suspicious AI config files
SELECT FullPath, Size, Mtime, Mode
FROM glob(globs='/*/Users/*/.config/openai/**')
  OR glob(globs='/*/Users/*/.config/claude/**')
  OR glob(globs='/*/Users/*/.anthropic/**')
WHERE Mtime > now() - 7d

Remediation Script (PowerShell)

PowerShell

<#
.SYNOPSIS
    Remediation script for AI Token Theft and Steam C2 indicators.
.DESCRIPTION
    Checks for suspicious AI config modifications and non-standard processes accessing Steam.
#>

# Check for recently modified AI Configuration Files
$aiPaths = @(
    "$env:APPDATA\OpenAI",
    "$env:USERPROFILE\.config\openai",
    "$env:USERPROFILE\.config\claude",
    "$env:USERPROFILE\.anthropic"
)

Write-Host "[*] Checking for recent modifications to AI configuration files..."
foreach ($path in $aiPaths) {
    if (Test-Path $path) {
        Get-ChildItem -Path $path -Recurse -File | 
        Where-Object { $_.LastWriteTime -gt (Get-Date).AddDays(-7) } | 
        Select-Object FullName, LastWriteTime, Length
    }
}

# Check for suspicious Steam connections (requires elevated privileges for netstat/checking handles)
Write-Host "[*] Auditing processes connecting to Steam Community..."
$steamHost = "steamcommunity.com"
# Get established TCP connections
$tcpConnections = Get-NetTCPConnection -State Established -ErrorAction SilentlyContinue

foreach ($conn in $tcpConnections) {
    try {
        $process = Get-Process -Id $conn.OwningProcess -ErrorAction Stop
        $remoteHost = (Resolve-DnsName -Name $conn.RemoteAddress -ErrorAction SilentlyContinue).NameHost
        
        if ($remoteHost -like "*$steamHost*" -and $process.ProcessName -notin @("steam", "steamwebhelper", "chrome", "msedge", "firefox")) {
            Write-Host "[!] Suspicious Process: $($process.ProcessName) (PID: $($process.Id)) connected to $remoteHost" -ForegroundColor Red
        }
    } catch {
        # Ignore errors resolving host or accessing process
    }
}

Write-Host "[*] Remediation scan complete."

Remediation

1. Contain and Block Steam C2

Network Filtering: If your business does not require access to Steam Community, block steamcommunity.com at the proxy or firewall level. If access is required (e.g., for marketing teams), implement strict allow-listing so that only authorized devices/browsers can reach this domain.
Host Isolation: For any endpoint flagged by the Sigma rules, isolate the host immediately and perform a full memory acquisition to identify the malware process communicating with Steam profiles.

2. Secure AI Infrastructure

Token Rotation: Assume any AI token stored in a local user profile or environment file is potentially compromised. Rotate all OpenAI, Anthropic, and other API keys immediately.
Secrets Management: Enforce the use of dedicated secrets managers (e.g., HashiCorp Vault, AWS Secrets Manager, or Azure Key Vault) rather than storing keys in ~/.config or .env files.
Application Verification: Verify the authenticity of "Codex" or AI-related remote UI tools. Only download such software from official vendor repositories. Check digital signatures before execution.

3. Operation Dragon Weave (Geopolitical)

Indicator Enrichment: If your organization has ties to the Czech Republic, Taiwan, or critical infrastructure sectors, ingest the specific IOCs (Indicators of Compromise) associated with Operation Dragon Weave into your SIEM.
Phishing Resilience: Reinforce anti-phishing training, specifically focusing on suspicious documents referencing geopolitical events or governmental correspondence.

Related Resources

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