Mac computers have long maintained a reputation for being immune to the digital threats that plague other operating systems. However, as of 2026, the landscape of macOS security has shifted significantly. While the core architecture remains robust, the sophistication of adware, browser hijackers, and sophisticated info-stealers has increased. Relying solely on the assumption that a Mac is inherently safe is no longer a viable security strategy. Understanding how to check for malware on Mac is a fundamental skill for maintaining digital privacy and system integrity.

Malware on a Mac rarely announces itself with a flashing red light. Instead, it operates in the shadows, consuming system resources, redirecting web traffic, or silently exfiltrating data. Identifying these threats requires a combination of observing behavioral anomalies and performing a systematic audit of the operating system's internal directories.

Identifying the red flags of macOS infection

Before diving into technical scans, observing how the machine behaves during daily tasks often provides the first set of clues. Malware often leaves a footprint that affects hardware performance and software stability.

Unexplained resource consumption

One of the most common indicators is a sudden drop in performance. If a Mac that usually handles multi-tasking with ease begins to lag, or if the cooling fans spin at high speeds while the computer is seemingly idle, background processes may be at work. Malicious scripts, particularly cryptocurrency miners or distributed denial-of-service (DDoS) bots, require significant CPU and RAM. When these scripts run, they deprive legitimate applications of the resources they need, leading to stutters and system heat.

Browser hijacking and unauthorized redirects

Modern macOS malware frequently targets the web browser. If the default search engine in Safari, Chrome, or Firefox has changed without consent, or if the homepage now points to an unfamiliar portal, a browser hijacker is likely present. Another sign is the persistent appearance of pop-up advertisements, even on reputable websites that typically do not display aggressive ads. These redirects are designed to generate fraudulent ad revenue or lead users to phishing sites.

Security software alerts and fake warnings

Scareware is a specific category of malware that attempts to trick users into believing their system is heavily infected. If windows appear on the screen claiming that "hundreds of viruses have been found" and urging the download of a specific cleanup tool, this is almost certainly the malware itself. Genuine macOS security alerts are integrated into the system notifications and do not use alarmist language or request immediate payment.

Anomalies in communication and accounts

If contacts report receiving strange emails or messages from your accounts that you did not send, the Mac might be part of a spam relay. Additionally, noticing unfamiliar login attempts on personal accounts (Google, iCloud, banking) can indicate that a keylogger or an info-stealer has compromised credentials stored on the device.

Leveraging built-in macOS security tools

Apple integrates several layers of security into macOS that work silently. Understanding these can help determine if the system's native defenses are being bypassed.

XProtect and MRT

XProtect is the built-in antivirus signature technology that scans for known malicious software. It updates automatically and works in the background when apps are first opened or modified. Accompanying it is the Malware Removal Tool (MRT), which specifically focuses on removing malware that has managed to find its way onto the system. While these are effective against known signatures, they may struggle with "zero-day" threats or highly customized scripts. Checking that the system is receiving "Security Responses and System Files" in the Software Update settings ensures these tools have the latest data.

Gatekeeper and Notarization

Gatekeeper ensures that only trusted software runs on the Mac. It checks if an app has been digitally signed by a recognized developer and notarized by Apple. If an app was installed by bypassing these warnings (e.g., via "Open Anyway" in System Settings), it increases the risk that the software contains hidden malicious payloads.

Step-by-step manual check for malware on Mac

If the system exhibits suspicious behavior but native tools haven't flagged anything, a manual audit is the next course of action. This involves looking into the areas where malware typically hides to ensure persistence across reboots.

1. Analyzing processes in Activity Monitor

Activity Monitor is the window into everything running on the Mac. To start a check:

  1. Open Activity Monitor from the Utilities folder within Applications.
  2. Click the CPU tab and sort by % CPU in descending order.
  3. Look for processes with names that are random strings of characters or names that mimic system processes but look slightly off (e.g., "com.apple.system.update" instead of a legitimate Apple daemon).
  4. Select a suspicious process and click the "i" (Information) button. Look at the "Open Files and Ports" tab. If the process is communicating with strange IP addresses or originates from a temporary folder in the User Library, it warrants further investigation.
  5. Research any unfamiliar process names online. Many legitimate macOS processes have obscure names, so verification is essential before taking action.

2. Auditing the Applications folder

The Applications folder is often the first place malware lands, disguised as a utility or a media player.

  • Review every item in the folder. If an app is present that was not intentionally installed, it should be treated as suspicious.
  • Pay close attention to "helpers" or "unloaders" that often accompany free software bundles.
  • Check the version and developer information by right-clicking an app and selecting Get Info. Legitimate software will usually have clear developer metadata.

3. Scanning hidden persistence directories

Malware stays on a Mac by placing small files in specific directories that tell the system to launch the malicious code every time the computer starts. These are known as LaunchAgents and LaunchDaemons. This is the most critical area for a manual check.

Access these folders by opening Finder, selecting Go > Go to Folder... from the menu bar, and entering the following paths one by one:

  • ~/Library/LaunchAgents (User-specific agents)
  • /Library/LaunchAgents (System-wide agents for all users)
  • /Library/LaunchDaemons (System-wide daemons that run at root level)

In these folders, you will see .plist files. Look for files named after the suspicious apps found earlier or files with names that don't match any known software. For example, a file named com.search.launcher.plist is a common indicator of a browser hijacker. If a suspicious file is found, do not simply delete the .plist file; note the path to the executable file mentioned inside it (which can be viewed with TextEdit) so that the actual malicious binary can be removed later.

4. Checking Login Items

Some malware uses the standard Login Items list to ensure it runs upon user login.

  1. Go to System Settings > General > Login Items.
  2. Look at the list of applications set to open at login.
  3. Check the "Allow in the Background" section. This is a newer feature in macOS that shows which apps have permission to run processes even when they aren't open. Disable anything that looks unnecessary or unrecognized.

5. Cleaning up browser extensions and settings

Since many modern threats are web-based, the browser is a primary hideout.

  • For Safari: Go to Settings > Extensions. Remove any extension that wasn't purposefully installed. Ad-trackers often masquerade as "Search Assistants" or "Shopping Tools."
  • For Chrome: Navigate to chrome://extensions and perform a similar audit. Also, check the "On startup" settings and the default search engine list.
  • Clear Cache: After removing extensions, clearing the browser cache and cookies is helpful to remove any persistent tracking scripts.

Utilizing Safe Mode for diagnosis

If the Mac is so infected that it is difficult to navigate the system or if the malware actively prevents the opening of Activity Monitor, booting into Safe Mode is a powerful diagnostic step.

Safe Mode does three main things:

  1. It performs a directory check of the startup disk.
  2. It loads only the essential kernel extensions.
  3. It prevents all third-party Login Items and LaunchAgents from starting.

For Apple Silicon Macs:

  1. Shut down the Mac.
  2. Press and hold the power button until "Loading startup options" appears.
  3. Select the startup disk, then press and hold the Shift key and click "Continue in Safe Mode."

For Intel-based Macs:

  1. Restart the Mac and immediately press and hold the Shift key.
  2. Release the key when the login window appears.

If the system performance improves drastically in Safe Mode, it confirms that the issue is caused by third-party software (likely malware or a corrupted background process) rather than a hardware fault or core OS issue.

The role of third-party scanners

While manual checking is thorough, it can be time-consuming and prone to human error. Reputable third-party malware scanners can complement manual efforts. When choosing a tool, avoid those that use aggressive marketing or make unrealistic claims about "speeding up your Mac by 500%." Instead, look for established security firms that provide on-demand scanning capabilities.

Running a scan with a dedicated tool can often catch fragments of malware hidden in deeper system layers, such as the /private/var/ or /private/etc/ directories, which are difficult for users to audit manually without technical expertise.

Advanced checks: Terminal and Network

For those comfortable with a command-line interface, the Terminal offers deeper insights.

  • List all active network connections: Using the command sudo lsof -i -P | grep -i "LISTEN" can show which processes are waiting for incoming connections. While many are legitimate (like file sharing), seeing an unrecognized process listening on a port can be a red flag.
  • Check for modified system files: The kextstat command allows users to see loaded kernel extensions. If an extension is not signed by Apple or a known developer, it could be a highly sophisticated rootkit.

Long-term prevention strategies

Checking for malware is a reactive measure. Transitioning to a proactive stance is the most effective way to secure a Mac in 2026.

Mindful installation habits

The majority of macOS malware requires the user to provide their administrator password at some point. Being cautious about when and why that password is requested is the best defense. Avoid downloading software from third-party "aggregator" sites that wrap legitimate apps in their own installers.

Keeping the OS updated

Apple frequently releases Rapid Security Responses. These are small updates that patch critical vulnerabilities being actively exploited in the wild. Ensuring that "Install Security Responses and system files" is checked in the Software Update settings allows the Mac to protect itself against the latest threats without requiring a full OS restart.

Using a non-administrator account

For daily tasks, using a Standard user account rather than an Administrator account can limit the damage malware can do. Since a standard account doesn't have the permission to modify system-level folders or install daemons without explicit escalation, many types of malware will fail to achieve persistence.

Summary of the check process

Regularly performing a manual check involves a quick scan of the Activity Monitor for resource hogs, a review of the LaunchAgents folders for unauthorized scripts, and a cleanup of browser extensions. By combining these manual audits with the native protections of macOS, users can maintain a high level of security. If a manual check reveals a threat that cannot be easily removed, or if the system remains unstable after cleaning, backing up personal data (avoiding system files) and performing a clean reinstall of macOS via Recovery Mode remains the most definitive way to ensure a clean slate.

Digital security on a Mac is no longer a set-it-and-forget-it affair. It requires active participation, a critical eye toward system behavior, and a willingness to look under the hood of the operating system. By following these steps, you can ensure your Mac remains the high-performance, secure tool it was designed to be.