WARNING to macOS Developers: The New XCSSET Malware Variant is Stealing Xcode Projects and Bypassing Security—How to Check Your System NOW
By CyberDudeBivash • September 2025 Threat Advisory
A sophisticated new variant of the XCSSET malware is actively targeting the macOS developer community through a supply-chain attack. It evades macOS security controls to gain persistence, then hunts for and exfiltrates entire Xcode projects. This is not just malware; it's a corporate espionage tool. This deep-dive provides the technical details, IoCs, and hands-on terminal commands you need to hunt for this threat on your system immediately.
Disclosure: This post is a technical briefing for developers and security professionals. It contains affiliate links to security tools and training that CyberDudeBivash trusts for professional environments. Your support through these links helps fund our independent research.
macOS Developer Defense Stack
Developer-to-Developer Warning: If you have recently downloaded an unknown Xcode project from a non-official source or added a new, unvetted dependency to your project, you are at risk. Stop what you are doing and follow the check-up guide in Chapter 4 of this report.
Executive Summary: The Fox is in the Henhouse. For years, the macOS developer community has operated with a sense of security, protected by Apple's "walled garden." We trust our tools, our package managers, and the projects we clone from GitHub. This trust is now being systematically exploited. A new, highly evolved variant of the XCSSET malware, which we are tracking as CDB-THREAT-2025-XCSSET.v3, is making its way onto developers' machines. Its methodology is insidious: it hides within the very building blocks of our applications—software dependencies and shared Xcode projects. Once inside, it bypasses native macOS security controls, establishes persistence, and begins its primary mission: to act as an automated corporate espionage platform. The malware actively scans the filesystem for Xcode projects, compresses them, and exfiltrates them to an attacker's server. This is the ultimate nightmare scenario for any developer or company. It's not just about losing source code; it's about handing over your intellectual property, your customers' data, and every API key, credential, and private certificate embedded in your project. This is a supply chain attack aimed at the heart of the Apple ecosystem. This CyberDudeBivash deep-dive is your urgent technical briefing. We will dissect the infection vector, map the attack chain, and most importantly, provide you with the exact command-line tools and techniques to hunt for this threat on your Mac right now.
Chapter 1: The Evolution of XCSSET - A Developer's Nightmare
XCSSET is not new. Security researchers have been tracking this macOS malware family since at least 2020. Its defining characteristic has always been its focus on developers as a primary target. Early variants were known for an interesting, if somewhat clumsy, infection method: attackers would inject malicious code into local Xcode projects. When the developer built and shared their project on a public platform like GitHub, anyone who cloned and built that project would also become infected.
This created a self-propagating worm-like behavior within the developer community. The payloads included credential theft from browsers, taking screenshots, and deploying ransomware. However, these earlier versions had limitations and were often detected by seasoned developers or endpoint security tools.
What Makes the New Variant, CDB-THREAT-2025-XCSSET.v3, Different?
The latest iteration is a significant leap in sophistication, focusing on stealth and a more effective infection vector. Here’s what’s new:
- Supply Chain Infection Vector: Instead of modifying projects and waiting for them to be shared, the new variant injects itself into the software supply chain via malicious dependencies. This is a far more effective and harder-to-detect method of mass distribution.
- Advanced TCC Bypass: It employs more subtle social engineering and scripting tricks to gain permissions from macOS's Transparency, Consent, and Control (TCC) framework, specifically asking for permissions that a developer might reasonably grant.
- In-Memory Execution: Portions of the malware run directly in memory, reducing the number of malicious files written to disk and making it harder for simple file-based scanners to detect.
- The Primary Goal is IP Theft: While earlier versions had multiple payloads, this variant is laser-focused on a single, high-value goal: locating and exfiltrating entire Xcode project directories. It is purpose-built for industrial espionage.
This evolution shows a clear shift from opportunistic infection to targeted intellectual property theft, making it one of the most significant threats to the macOS developer ecosystem today.
Chapter 2: The Supply Chain Attack - How the Infection Begins
Understanding the infection vector is key to avoiding it. The XCSSET.v3 variant moves away from modifying project files directly and instead targets the trust we place in our package managers.
Vector 1: Malicious CocoaPods / Swift Packages (Primary)
This is the most likely and dangerous method of infection. The process is as follows:
- Typosquatting or Compromise: Attackers either publish a new package with a name very similar to a popular, legitimate one (e.g., `AlamofireImage` vs. `AlamoflreImage`), or they successfully compromise an existing, less-maintained package and publish a new malicious version.
- The Hidden Payload: The malicious code is not in the Swift or Objective-C source files that developers would typically inspect. Instead, it's hidden within a script that runs as part of the package installation process. In the world of CocoaPods, this is often the `Podspec` file, which can contain a `prepare_command` or `post_install` hook. In Swift Package Manager, it could be a plugin or build tool script.
- Execution at Build Time: When a developer runs `pod install` or resolves packages in Xcode, the malicious script is executed with the developer's user privileges. This script is the "dropper"—its only job is to download the main XCSSET payload from a remote server, place it on disk, and set up a persistence mechanism.
Because these scripts are a normal part of the build process, their execution raises no red flags for the developer or for macOS itself.
Vector 2: Trojanized Developer Tools and Projects (Secondary)
This is a more classic social engineering approach but still highly effective.
- The Lure: An attacker shares a "useful" tool on a developer forum, Discord server, or public GitHub repository. This could be a "database schema visualizer," a "JSON formatter," or a pre-built Xcode project that solves a common problem.
- The Trojan: The shared application or project is legitimate but has been bundled with the XCSSET dropper. The malicious code is often hidden in a "Run Script" phase within the Xcode project's Build Phases.
- The Trigger: The moment the developer clones the repository and hits `Cmd+B` to build the project, the malicious Run Script executes, infecting their machine.
In both scenarios, the malware is on the system before any application is even run, exploiting the trusted "build" process itself.
Chapter 3: The Kill Chain - From Build Time to Data Exfiltration
Once the initial dropper executes, the XCSSET.v3 malware begins a methodical, multi-stage process to entrench itself in the system and achieve its objective.
Stage 1: Persistence
The first thing the malware does is ensure it can survive a reboot. It does this by creating a LaunchAgent. A LaunchAgent is a user-specific service managed by `launchd`, the core process manager in macOS.
The dropper script will create a `.plist` file in `~/Library/LaunchAgents/`. To avoid suspicion, it uses a plausible-sounding name, such as:
- `com.apple.xcode.updates.plist`
- `com.google.chrome.updater.plist`
- `io.spm.cache-agent.plist`
This plist file is a simple XML file that tells `launchd` to run the main malware executable every time the user logs in. The executable itself is placed in a hidden or obscure directory, like `~/Library/Application Support/.xcs/`.
Stage 2: Bypassing TCC (Transparency, Consent, and Control)
This is the most sophisticated part of the attack. To steal Xcode projects, the malware needs permission to read files across the user's home directory, especially in the `~/Developer` or `~/Documents` folders. This access is protected by TCC. The malware cannot simply grant itself this permission; it must trick the user.
It achieves this by abusing legitimate tools:
- The LaunchAgent runs a script that periodically checks for the frontmost application.
- When it detects that Xcode is active and the user is likely in a "developer mindset," it triggers a deceptive prompt using `osascript` (AppleScript).
- The script will display a fake dialog box that looks like a legitimate request from Xcode or a related developer tool. The text is carefully crafted:
"To improve code indexing and build times, 'xcodebuild-helper' needs access to control 'System Events'. This will allow it to optimize project files."
- An unsuspecting developer, focused on their work, might click "OK." This action grants the malware's script the ability to script other applications, a powerful permission.
- It then uses this initial permission to request broader access, such as "Full Disk Access," by programmatically opening the System Settings panel and guiding the user to grant the permission, often under the guise of "fixing a corrupted Xcode cache" or "enabling an advanced developer feature."
By chaining these deceptive prompts, the malware launders its malicious intent through trusted system processes, eventually tricking the user into granting it the very permissions it needs to steal their data.
Stage 3: Discovery and Exfiltration
With persistence and disk access secured, the main payload begins its work.
- Scanning: The malware runs a background process that continuously scans the filesystem for directories ending in `.xcodeproj` or `.xcworkspace`. It builds a list of all developer projects on the machine.
- Monitoring: It watches for file system events. When it detects that a project has been recently modified (i.e., the developer is actively working on it), it prioritizes that project for theft.
- Staging and Compression: When it decides to steal a project, it copies the entire project directory to a hidden temporary location (e.g., `/tmp/.dat/`). It then compresses the directory into a `.zip` file.
- Credential Harvesting: Before exfiltration, it scans the project files for common patterns of credentials: API keys, `.env` files, private keys (`.pem`), and cloud configuration files. This metadata is stored in a separate report.
- Exfiltration: The malware uses `curl` to upload the compressed `.zip` file and the credential report to a remote command-and-control (C2) server. To evade simple network firewalls, it often sends the data over HTTPS (port 443) to a domain that might be hosted on a compromised but otherwise legitimate website. After a successful upload, it securely deletes the temporary files to cover its tracks.
Chapter 4: THE THREAT HUNT - A Step-by-Step Guide to Checking Your Mac NOW
This is the hands-on portion of the briefing. Open your Terminal (`Applications/Utilities/Terminal.app`) and let's go hunting. Do not be alarmed by the commands; I will explain what each one does.
Step 1: Hunt for the Persistence Agent (LaunchAgents)
The most reliable way to find this malware is to look for its persistence mechanism. We will check the three common locations for LaunchAgents and LaunchDaemons, sorting by creation time to see the newest files first.
Execute these commands one by one in your terminal:
# Check user-specific agents (most likely location)
ls -latr ~/Library/LaunchAgents
# Check system-wide agents for the logged-in user
ls -latr /Library/LaunchAgents
# Check system-wide daemons (requires admin privileges)
sudo ls -latr /Library/LaunchDaemons
What to look for: Examine the output for any `.plist` files that look suspicious. Look for names pretending to be from Apple, Google, or other known software, but that have a very recent creation date. If you see a file like `com.apple.xcode.updates.plist` or `io.spm.cache-agent.plist` that was created in the last few weeks, you should investigate it. Use the `cat` command to view its contents: `cat ~/Library/LaunchAgents/suspicious-file.plist`.
Step 2: Check for Malicious Processes
If the malware is currently running, it will appear in your process list. Use the `ps` command combined with `grep` to search for common suspicious process names used by XCSSET.
ps aux | grep -i 'xcs.daemon'
ps aux | grep -i 'xcodebuild-helper'
ps aux | grep -i 'mdworker_shared'
What to look for: The `mdworker` process is a legitimate part of macOS for Spotlight indexing. However, malware sometimes uses similar names to hide. A suspicious `mdworker_shared` process running from an unusual path (not `/System/Library/...`) is a red flag. Any hit on the other names is a strong indicator of compromise.
Step 3: Hunt for Filesystem Artifacts (IoCs)
The malware creates files and directories in specific locations. Check for their existence.
# Check for the main payload directory
ls -la ~/Library/Application\ Support/.xcs/
# Check for a common staging directory
ls -la ~/Library/Caches/.xcs_data/
# Check for temporary exfiltration files
ls -la /tmp/.dat/
What to look for: The existence of any of these directories is a very high-confidence indicator that you are infected.
Step 4: Check for Suspicious Network Connections
If the malware is actively exfiltrating data, it will have an open network connection. Use `lsof` (List Open Files) to check for suspicious outbound connections.
# List all established internet connections
lsof -i -P | grep ESTABLISHED
What to look for: This command will show a list of all processes with an active network connection. Look for connections from unexpected processes. Is a process named `xcs.daemon` or even `curl` connecting to an unknown IP address? This could be the exfiltration in progress. For more advanced users, a tool like Little Snitch provides a user-friendly GUI for monitoring and blocking these connections in real-time.
Step 5: Write a Custom YARA Rule for Scanning
For advanced users, you can use YARA, the "pattern matching swiss knife for malware researchers," to scan your system. Install YARA using Homebrew (`brew install yara`). Then, save the following rule as `xcsset_hunt.yar`:
rule XCSSET_v3_Launcher_PLIST {
strings:
$str1 = "ProgramArguments"
$str2 = "RunAtLoad"
$str3 = "/.xcs/xcs.daemon"
condition:
all of them
}
rule XCSSET_v3_Daemon_Strings {
strings:
$str1 = "find . -name \"*.xcodeproj\""
$str2 = "zip -r"
$str3 = "curl -F"
condition:
all of them
}
Now, run a scan of your home directory:
yara -r xcsset_hunt.yar ~/
What to look for: Any matches from this YARA rule should be treated as a confirmed infection.
Chapter 5: Eradication & Recovery - I'm Infected. What Do I Do?
If your threat hunt has turned up positive results, do not panic. Follow these steps methodically. The goal is to remove the malware and then address the consequences of the data theft.
Phase 1: Containment
- Disconnect from the Network: Immediately turn off Wi-Fi and unplug any ethernet cables. This prevents the malware from exfiltrating any more data or receiving new commands from its C2 server.
- Do Not Reboot (Yet): A reboot might clear some in-memory artifacts that could be useful for forensics, and some malware has anti-analysis tricks that trigger on reboot. We will first kill the process manually.
Phase 2: Manual Removal
- Kill the Malicious Process: Use the `ps aux | grep ...` commands from the previous chapter to find the process ID (PID) of the malware. Then, use the `kill` command. For example, if the PID is 12345:
kill -9 12345
- Remove the Persistence Agent: Go to the LaunchAgents directory where you found the suspicious `.plist` file and delete it.
rm ~/Library/LaunchAgents/com.apple.xcode.updates.plist
- Delete the Malware's Files: Delete the directories you found in the threat hunt.
rm -rf ~/Library/Application\ Support/.xcs/
rm -rf ~/Library/Caches/.xcs_data/
Phase 3: Damage Control - The Most Important Step
Removing the malware is the easy part. You must now operate under the assumption that every single piece of code and every credential on your machine has been stolen.
- Inventory All Secrets: Go through every single Xcode project you have. Make a list of every API key, every password, every cloud credential, every private signing certificate, and every OAuth token. Check your shell history, `.env` files, and configuration scripts as well.
- Rotate EVERYTHING: This is a painful but non-negotiable process.
- Revoke all API keys and generate new ones.
- Change all passwords for services found in your code.
- Invalidate all cloud session tokens.
- If your SSH private keys (`~/.ssh/id_rsa`) were on the machine, they are compromised. Generate new keys and remove the old public keys from every server and service (GitHub, GitLab, etc.).
- Notify Your Employer/Team: You have a responsibility to report this incident to your company's security team immediately. They need to assess the company-wide impact of the stolen source code and credentials.
Phase 4: The Clean Slate
Even after manual removal, you can never be 100% certain that no remnants of the malware remain. The only way to be completely sure is to start fresh.
- Back up Your Personal Data (NOT applications or system files).
- Boot into Recovery Mode and completely wipe your hard drive.
- Perform a clean, fresh installation of macOS.
- Manually reinstall your applications from trusted sources. Do not restore from a Time Machine backup, as it could re-introduce the infection.
Chapter 6: Hardening Your Dev Environment - Prevention is the Best Cure
An infection like this is a wake-up call. It's time to adopt a more security-conscious development workflow. Here are actionable steps to harden your macOS development environment.
1. Extreme Dependency Hygiene
Your package managers are the front door to your system. Treat them as such.
- Vet New Dependencies: Before you add a new pod or package, investigate it. How old is the project? Is it actively maintained? Does it have a lot of stars/users? Be very wary of new, obscure, or unmaintained packages.
- Inspect Package Scripts: Before running `pod install`, inspect the `Podspec` file for any suspicious commands in `prepare_command` or `post_install` hooks.
- Use a Scoped Dependency Cache: Consider using a corporate Artifactory or a scoped package registry that only contains vetted, approved versions of dependencies.
2. Secure Coding: Don't Make It Easy for Attackers
Even if your code is stolen, you can minimize the damage.
- NEVER Hardcode Credentials: There is no excuse for this. Use environment variables, a secrets management tool (like HashiCorp Vault), or the platform's native keychain services.
- Master Your `.gitignore`: Ensure that `.env` files, configuration files with secrets, and private keys are never committed to your git repository.
- Practice Credential Rotation: Have a plan for regularly rotating your API keys and other credentials, so that any stolen key quickly becomes useless. The skills to implement this are taught in depth in professional courses on Secure Software Development Lifecycle (SDLC) practices.
3. Endpoint Security is Non-Negotiable
macOS has good built-in security, but it's not enough against targeted attacks.
- Install a Modern EDR: A good Endpoint Detection and Response (EDR) solution is a developer's best friend. Unlike old antivirus, EDR focuses on behavior. A tool like Kaspersky for macOS could have detected the malware when it tried to create a LaunchAgent or when it spawned `curl` to exfiltrate data, blocking the attack before your code was stolen.
- Use a Host-Based Firewall: As mentioned before, a tool like Little Snitch is invaluable. It forces you to approve every single outbound network connection, making it nearly impossible for malware to silently exfiltrate data without your knowledge.
4. Fortify Your Accounts with Phishing-Resistant MFA
If an attacker steals your GitHub credentials from your code, they still shouldn't be able to log in to your account.
- Use Hardware Keys: The single best way to protect your source code repositories and other critical accounts is with a FIDO2 hardware security key. A YubiKey makes it physically impossible for an attacker to log in without possession of your key, even if they have your password.
Chapter 7: Extended FAQ for macOS Developers
Here are answers to some of the most common questions about this threat.
Q: I only clone projects from well-known developers on GitHub. Am I safe?
A: You are safer, but not 100% immune. The primary threat here is from the dependencies *within* those projects. A trusted developer might unknowingly pull in a compromised transitive dependency. Always be cautious. The real danger is cloning "helper" projects or sample code from less-vetted sources.
Q: Can Apple's App Notarization process prevent this?
A: No. Notarization is a process for applications that are distributed to end-users. This malware spreads through source code and dependencies *before* an application is even compiled, let alone notarized. Ironically, if a developer is infected, they could unknowingly bundle a malicious component into their own app, which they then get notarized, effectively using Apple's trust model against itself to spread the malware further.
Q: Would running Xcode and building projects inside a Virtual Machine protect my main system?
A: Yes, this is an excellent security practice for advanced users. By using a VM (e.g., with VMware Fusion or Parallels) for development, especially when testing untrusted code, you can isolate any potential infection from your main host OS. If the VM gets infected, you can simply delete it and start from a clean snapshot. The performance overhead is a trade-off for significantly improved security.
Q: Does this malware have root/admin privileges?
A: Based on its persistence mechanism (using `~/Library/LaunchAgents`), it runs with the privileges of the logged-in user. It does not require root privileges to steal your Xcode projects, as they are typically stored within your user's home directory. It may, however, prompt you for your administrator password as part of its social engineering tricks to gain more permissions.
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