What Is CheckLetter Mac Adware?
CheckLetter is a potentially unwanted application (PUA) targeting macOS users. The app also has adware capabilities, meaning that it could trigger advertisements and affect your browsers. In some cases, apps such as CheckLetter also feature a browser extension that gets installed automatically, without your initial approval or consent. You may notice that your default search engine is changed to a suspicious one. This may have been done to redirect your searches or show you sponsored results.
Many other similar programs are currently targeting Mac users, proving that no operation system is safe from adware. Other examples include AboudDynamic, ElementSignal, and UpdateAgent. It should also be noted that PUAs often contain trojan capabilities, meaning that they could open a backdoor to other, more severe threats.
Yes, adware usually doesn’t belong to the same category as malicious software. However, a recent research conducted by researchers at Concordia University in Montreal, Canada, reveals that adware is in fact very similar to malicious code and its techniques. To prove that, the researchers investigated the evolution of a well-known adware called Wajam, in the course of nearly six years. Wajam has been known to inject ads into browser traffic, using techniques that malware operators use, such as man-in-the-browser (browser process injection) attacks seen in Zeus operations. Other examples include anti-analysis and evasion techniques, security policy downgrading and data leakage.
So, shortly said, don’t underestimate the capabilities of suspicious applications, including CheckLetter and its alikes.
Threat Summary
| Name | CheckLetter |
| Type | Potentially Unwanted Program / Adware / Browser Hijacker |
| Short Description | A potentially unwanted app. This program aims to heavily modify your web browsers’ settings to display ads and redirect you to suspicious pages. |
| Symptoms | Preferred web browser is configured to redirect you to unwanted pages. Slower Mac performance could be experienced as well. |
| Distribution Method | Software Bundles, Corrupted Installers, Bogus Websites/Webpages |
| Detection Tool |
See If Your System Has Been Affected by malware
Combo Cleaner
Malware Removal Tool
|
User Experience | Join Our Forum to Discuss CheckLetter. |
CheckLetter Adware – How Did It Get Installed on My Mac?
Several techniques are usually deployed for the distribution of the CheckLetter adware. A significant distribution technique is software bundling. Bundling revolves around programs that pretend to be useful and legit but come bundled with ad-supported apps.
The purpose of bundling is quick monetization. Commonly used software may deliver unwanted apps. This includes media players, file converters, weather toolbars, online streaming apps, etc.
The installers of these programs often present optional offers or free extras. At the same time, they are not designed to appropriately disclose information about added apps. That’s how users fail to notice their presence during the installation of whatever software they wanted to download.
Other scenarios include users interacting with suspicious pages (torrenting and online streaming websites, adult pages, free online games, etc.). On these pages, users may click on suspicious links, banners, and offers,. The result may be an unnoticed download and install of a potentially unwanted program. And then the annoying browser redirects originate.
N.B. Once started on your Mac, such a program could access all installed browsers’ settings to apply significant changes. One of these changes often affects the default search engine in your preferred web browser. If your default search engine is altered without your consent, then don’t waste time but go check your macOS security. This problem is a definite sign that a suspicious piece of software has sneaked into your system.
Furthermore, as long as files associated with the CheckLetter adware are running on your Mac, you may be a victim of unsolicited data collection.
By activating different tracking technologies like cookies, web beacons, javascript, or even Trojans, the undesired application may become able to obtain a long list of sensitive details, including:
- Visited URLs and websites
- Browser’s home page
- Search queries
- Search queries on the visited web pages
- Type of used browser
- Operating system type
- Internet protocol (IP) address
- Geographic location
- The domain name of the current Internet service provider (ISP)
- Banking credentials
- Entered keystrokes
Fraudsters may use data records to launch targeted advertising campaigns. Once the data is available on the PUP’s servers, it can be used for the identification of your online interests. Ads delivered by undesired apps may target your interests. At worst, data records will be released on dark web markets for additional revenue.
Remove CheckLetter from Your Mac
To remove all files associated with the CheckLetter appearance on Mac, you should complete several removal steps. The guide below will reveal all removal steps in their precise order, including manual and automatic actions. To fully eliminate the undesired program that brought the Safari redirect virus, we recommend you combine the steps. Please keep in mind that you can minimize the risk of missing harmful files by using the help of an advanced anti-spyware tool. Further, you can protect your operating system by using such a tool. It will identify and stop insider threats before they cause damage.
In case you have further questions or need additional help, don’t hesitate to leave a comment or contact us via email.
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An inspired writer and content manager who has been with SensorsTechForum since the project started. A professional with 10+ years of experience in creating engaging content. Focused on user privacy and malware development, she strongly believes in a world where cybersecurity plays a central role. If common sense makes no sense, she will be there to take notes. Those notes may later turn into articles! Follow Milena @Milenyim
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Steps to Prepare Before Removal:
Before starting to follow the steps below, be advised that you should first do the following preparations:
- Backup your files in case the worst happens.
- Make sure to have a device with these instructions on standy.
- Arm yourself with patience.
- 1. Scan for Mac Malware
- 2. Uninstall Risky Apps
- 3. Clean Your Browsers
Step 1: Scan for and remove CheckLetter files from your Mac
When you are facing problems on your Mac as a result of unwanted scripts and programs such as CheckLetter, the recommended way of eliminating the threat is by using an anti-malware program. SpyHunter for Mac offers advanced security features along with other modules that will improve your Mac’s security and protect it in the future.
Quick and Easy Mac Malware Video Removal Guide
Bonus Step: How to Make Your Mac Run Faster?
Mac machines maintain probably the fastest operating system out there. Still, Macs do become slow and sluggish sometimes. The video guide below examines all of the possible problems that may lead to your Mac being slower than usual as well as all of the steps that can help you to speed up your Mac.
Step 2: Uninstall CheckLetter and remove related files and objects
1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:
2. Find Activity Monitor and double-click it:
3. In the Activity Monitor look for any suspicious processes, belonging or related to CheckLetter:
4. Click on the "Go" button again, but this time select Applications. Another way is with the ⇧+⌘+A buttons.
5. In the Applications menu, look for any suspicious app or an app with a name, similar or identical to CheckLetter. If you find it, right-click on the app and select “Move to Trash”.
6. Select Accounts, after which click on the Login Items preference. Your Mac will then show you a list of items that start automatically when you log in. Look for any suspicious apps identical or similar to CheckLetter. Check the app you want to stop from running automatically and then select on the Minus (“-“) icon to hide it.
7. Remove any leftover files that might be related to this threat manually by following the sub-steps below:
- Go to Finder.
- In the search bar type the name of the app that you want to remove.
- Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
- If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.
In case you cannot remove CheckLetter via Step 1 above:
In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:
1. Click on "Go" and Then "Go to Folder" as shown underneath:
2. Type in "/Library/LauchAgents/" and click Ok:
3. Delete all of the virus files that have similar or the same name as CheckLetter. If you believe there is no such file, do not delete anything.
You can repeat the same procedure with the following other Library directories:
→ ~/Library/LaunchAgents
/Library/LaunchDaemons
Tip: ~ is there on purpose, because it leads to more LaunchAgents.
Step 3: Remove CheckLetter – related extensions from Safari / Chrome / Firefox
CheckLetter-FAQ
What is CheckLetter on your Mac?
The CheckLetter threat is probably a potentially unwanted app. There is also a chance it could be related to Mac malware. If so, such apps tend to slow your Mac down significantly and display advertisements. They could also use cookies and other trackers to obtain browsing information from the installed web browsers on your Mac.
Can Macs Get Viruses?
Yes. As much as any other device, Apple computers do get malware. Apple devices may not be a frequent target by malware authors, but rest assured that almost all of the Apple devices can become infected with a threat.
What Types of Mac Threats Are There?
According to most malware researchers and cyber-security experts, the types of threats that can currently infect your Mac can be rogue antivirus programs, adware or hijackers (PUPs), Trojan horses, ransomware and crypto-miner malware.
What To Do If I Have a Mac Virus, Like CheckLetter?
Do not panic! You can easily get rid of most Mac threats by firstly isolating them and then removing them. One recommended way to do that is by using a reputable malware removal software that can take care of the removal automatically for you.
There are many Mac anti-malware apps out there that you can choose from. SpyHunter for Mac is one of the reccomended Mac anti-malware apps, that can scan for free and detect any viruses. This saves time for manual removal that you would otherwise have to do.
How to Secure My Data from CheckLetter?
With few simple actions. First and foremost, it is imperative that you follow these steps:
Step 1: Find a safe computer and connect it to another network, not the one that your Mac was infected in.
Step 2: Change all of your passwords, starting from your e-mail passwords.
Step 3: Enable two-factor authentication for protection of your important accounts.
Step 4: Call your bank to change your credit card details (secret code, etc.) if you have saved your credit card for online shopping or have done online activiites with your card.
Step 5: Make sure to call your ISP (Internet provider or carrier) and ask them to change your IP address.
Step 6: Change your Wi-Fi password.
Step 7: (Optional): Make sure to scan all of the devices connected to your network for viruses and repeat these steps for them if they are affected.
Step 8: Install anti-malware software with real-time protection on every device you have.
Step 9: Try not to download software from sites you know nothing about and stay away from low-reputation websites in general.
If you follow these reccomendations, your network and Apple devices will become significantly more safe against any threats or information invasive software and be virus free and protected in the future too.
More tips you can find on our MacOS Virus section, where you can also ask any questions and comment about your Mac problems.
About the CheckLetter Research
The content we publish on SensorsTechForum.com, this CheckLetter how-to removal guide included, is the outcome of extensive research, hard work and our team’s devotion to help you remove the specific macOS issue.
How did we conduct the research on CheckLetter?
Please note that our research is based on an independent investigation. We are in contact with independent security researchers, thanks to which we receive daily updates on the latest malware definitions, including the various types of Mac threats, especially adware and potentially unwanted apps (PUAs).
Furthermore, the research behind the CheckLetter threat is backed with VirusTotal.
To better understand the threat posed by Mac malware, please refer to the following articles which provide knowledgeable details.