Removing PDFCastle unwanted app and the redirects it causes to pdfcastle.com
Written by Tomas Meskauskas on
What kind of application is PDFCastle?
Our researchers discovered PDFCastle PUA (Potentially Unwanted Application) while inspecting untrustworthy websites. According to its promotional material, this app allows users to view, create, edit, and convert PDFs to other formats (including Microsoft Word documents).
Instead of operating as advertised, PDFCastle endorses the portal.pdfcastle.com fake search engine. This application might possess other harmful capabilities as well. It is pertinent to mention that PUAs are often bundled with other suspicious software.
PDFCastle overview
As mentioned in the introduction, PDFCastle promotes portal.pdfcastle.com – a fake search engine. Websites of this kind are typically endorsed by software classed as browser hijackers. However, this app does not modify browsers.
Hijacker software changes browser settings (e.g., homepages, default search engines, new tabs/windows, etc.) to generate redirects that land on endorsed sites when a user enters a search query into the URL bar or opens a new browser tab/window. On the other hand, PDFCastle only opens portal.pdfcastle.com once the application's shortcut is launched.
Illegitimate search engines cannot provide search results, so they lead users to genuine Internet search websites. Portal.pdfcastle.com is no exception; we observed it landing on nearbyme.io and Yahoo (search.yahoo.com).
The former is likewise a fake search engine, but unlike most – nearbyme.io can generate search results, yet they are inaccurate and may include unreliable, deceptive, and possibly malicious content. It is pertinent to mention that webpages like portal.pdfcastle.com usually collect information concerning their visitors.
Furthermore, PDFCastle may have data-tracking functionalities, as they are common in PUAs. Targeted information can include: browsing and search engine histories, Internet cookies, log-in credentials (usernames/passwords), personally identifiable details, finance-related data, and so on. This vulnerable information can be shared with or sold to third-parties (potentially, cyber criminals).
To summarize, the presence of unwanted software like PDFCastle on devices can result in system infections, serious privacy issues, financial losses, and even identity theft.
| Name | PDFCastle unwanted application |
| Threat Type | PUP (Potentially Unwanted Program), PUA (Potentially Unwanted Application) |
| Supposed Functionality | Viewing, creating, editing, and converting PDF format files. |
| Detection Names (installer) | Avast (Win32:Malware-gen), Combo Cleaner (Gen:Variant.Ser.Lazy.6004), ESET-NOD32 (A Variant Of MSIL/MediaArena.D Potenti), Malwarebytes (PUP.Optional.MediaArena), Microsoft (BrowserModifier:MSIL/MediaArena), Full List Of Detections (VirusTotal) |
| Promoted Domains | pdfcastle.com |
| Detection Names (pdfcastle.com) | Combo Cleaner (Malware), CyRadar (Malicious), G-Data (Malware), Webroot (Malicious), Forcepoint ThreatSeeker (Suspicious), Full List Of Detections (VirusTotal) |
| Serving IP Address (pdfcastle.com) | 13.107.246.51 |
| Symptoms | A program that you do not recall installing suddenly appeared on your computer. Rogue redirects. Decreased Internet browsing speed. |
| Distribution Methods | Deceptive pop-up ads, free software installers (bundling). |
| Damage | Users are forced to visit the hijacker's website and search the Internet using their search engines. Potential privacy issues and monetary losses. |
| Malware Removal (Windows) | To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. |
Potentially unwanted application examples
PdfKnight is an example of a PUA that operates in the same manner as PDFCastle, while TjboApp, CiviApp, Mixability, and DrawPad Graphic Design are just some of our latest articles on unwanted apps.
These applications typically appear legitimate and innocuous. They can also offer various functions, such as PDFCastle, which promises to enable users to modify and convert PDF format documents. However, unwanted app functionalities seldom work as promised, and in most cases – they are utterly nonoperational.
It must be emphasized that functional features alone do not prove a software's legitimacy or safety.
How did potentially unwanted applications install on my computer?
We downloaded PDFCastle from its "official" promotional webpage. However, this app could also be endorsed using other methods. PUA-promoting sites can appear legitimate or use social engineering (like scare tactics) to trick users into downloading.
These pages are primarily entered via redirects caused by intrusive ads, websites using rogue advertising networks, misspelled URLs, spam browser notifications, and installed adware.
Additionally, "bundling" – packing ordinary program installers with unwanted/malicious additions – is used to proliferate apps of this kind.
Downloading from dubious channels (e.g., freeware and third-party websites, Peer-to-Peer sharing networks, etc.) and treating installations with negligence (e.g., ignoring terms, using "Easy/Quick" options, etc.) – increase the risk of inadvertently allowing bundled content into the system.
Intrusive advertisements proliferate unwanted software as well. Once clicked on, some of the adverts can execute scripts to perform downloads/installations without user consent.
How to avoid installation of potentially unwanted applications?
We strongly advise researching software prior to downloading or purchasing. Furthermore, all downloads must be performed from official and trustworthy sources. When installing, we recommend studying terms and options, using the "Custom" or "Advanced" settings, and opting out of all additions (e.g., apps, tools, extensions, features, etc.).
Another recommendation is to be vigilant while browsing, as fake and malicious online content typically appears genuine and harmless. For example, while intrusive ads may look innocuous – they redirect users to unreliable and questionable sites (e.g., scam-promoting, pornography, gambling, adult dating, etc.).
If you keep encountering advertisements and/or redirects of this kind, inspect the system and immediately remove all suspect applications and browser extensions/plug-ins. If your computer is already infected with PUAs, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate them.
Appearance of portal.pdfcastle.com redirecting to the nearbyme.io fake search engine (GIF):
PDFCastle application's official promotional website:
Installation setup of PDFCastle application:
PDFCastle application's shortcut details (promoting portal.pdfcastle.com):
Instant automatic malware removal:
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Quick menu:
- What is PDFCastle?
- STEP 1. Uninstall deceptive applications using Control Panel.
- STEP 2. Remove rogue extensions from Google Chrome.
- STEP 3. Remove potentially unwanted plug-ins from Mozilla Firefox.
- STEP 4. Remove rogue extensions from Safari.
- STEP 5. Remove rogue plug-ins from Microsoft Edge.
Removal of potentially unwanted applications:
Windows 11 users:
Right-click on the Start icon, select Apps and Features. In the opened window search for the application you want to uninstall, after locating it, click on the three vertical dots and select Uninstall.
Windows 10 users:
Right-click in the lower left corner of the screen, in the Quick Access Menu select Control Panel. In the opened window choose Programs and Features.
Windows 7 users:
Click Start (Windows Logo at the bottom left corner of your desktop), choose Control Panel. Locate Programs and click Uninstall a program.
macOS (OSX) users:
Click Finder, in the opened screen select Applications. Drag the app from the Applications folder to the Trash (located in your Dock), then right click the Trash icon and select Empty Trash.
In the uninstall programs window, look for "PDFCastle" and other suspicious/recently-installed applications, select these entries and click "Uninstall" or "Remove".
After uninstalling the potentially unwanted application, scan your computer for any remaining unwanted components or possible malware infections. To scan your computer, use recommended malware removal software.
Remove rogue extensions from Internet browsers:
At time of research, PDFCastle did not install any unwanted browser extensions, however, some unwanted applications can be installed together with adware and browser hijackers. If you experience unwanted ads or redirects when browsing the Internet, continue with the removal guide below.
Video showing how to remove potentially unwanted browser add-ons:
Remove malicious extensions from Google Chrome:
Click the Chrome menu icon 
(at the top right corner of Google Chrome), select "More Tools" and click "Extensions". Locate all recently-installed suspicious extensions, select these entries and click "Remove".
Optional method:
If you continue to have problems with removal of the pdfcastle unwanted application, reset your Google Chrome browser settings. Click the Chrome menu icon (at the top right corner of Google Chrome) and select Settings. Scroll down to the bottom of the screen. Click the Advanced… link.
After scrolling to the bottom of the screen, click the Reset (Restore settings to their original defaults) button.
In the opened window, confirm that you wish to reset Google Chrome settings to default by clicking the Reset button.
Remove malicious plugins from Mozilla Firefox:
Click the Firefox menu 
(at the top right corner of the main window), select "Add-ons and themes". Click "Extensions", in the opened window locate all recently-installed suspicious extensions, click on the three dots and then click "Remove".
Optional method:
Computer users who have problems with pdfcastle unwanted application removal can reset their Mozilla Firefox settings.
Open Mozilla Firefox, at the top right corner of the main window, click the Firefox menu, in the opened menu, click Help.
Select Troubleshooting Information.
In the opened window, click the Refresh Firefox button.
In the opened window, confirm that you wish to reset Mozilla Firefox settings to default by clicking the Refresh Firefox button.
Remove malicious extensions from Safari:
Make sure your Safari browser is active, click Safari menu, and select Preferences....
In the opened window click Extensions, locate any recently installed suspicious extension, select it and click Uninstall.
Optional method:
Make sure your Safari browser is active and click on Safari menu. From the drop down menu select Clear History and Website Data...
In the opened window select all history and click the Clear History button.
Remove malicious extensions from Microsoft Edge:
Click the Edge menu icon 
(at the upper-right corner of Microsoft Edge), select "Extensions". Locate all recently-installed suspicious browser add-ons and click "Remove" below their names.
Optional method:
If you continue to have problems with removal of the pdfcastle unwanted application, reset your Microsoft Edge browser settings. Click the Edge menu icon (at the top right corner of Microsoft Edge) and select Settings.
In the opened settings menu select Reset settings.
Select Restore settings to their default values. In the opened window, confirm that you wish to reset Microsoft Edge settings to default by clicking the Reset button.
- If this did not help, follow these alternative instructions explaining how to reset the Microsoft Edge browser.
Summary:
Commonly, adware or potentially unwanted applications infiltrate Internet browsers through free software downloads. Note that the safest source for downloading free software is via developers' websites only. To avoid installation of adware, be very attentive when downloading and installing free software. When installing previously-downloaded free programs, choose the custom or advanced installation options – this step will reveal any potentially unwanted applications listed for installation together with your chosen free program.
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Frequently Asked Questions (FAQ)
What is the purpose of forcing users to visit portal.pdfcastle.com website?
The motivation behind developing software that generates redirects or otherwise promotes fake search engines (e.g., portal.pdfcastle.com, etc.) is profit. In other words, the software developers/publishers generate revenue through redirects to such websites.
Is visiting portal.pdfcastle.com a threat to my privacy?
It is likely a minor privacy threat, as fake search engines (e.g., portal.pdfcastle.com, etc.) typically collect (and sell) visitor data.
What is the purpose of an unwanted application?
The purpose of unwanted applications is to generate revenue for their developers/publishers. This goal may be achieved by endorsing content (via redirects, ads, etc.), tricking users into buying fake activation keys, promoting in-app purchases, collecting/selling private information, and so forth.
Is PDFCastle unwanted application legal?
In most cases, unwanted applications are deemed legal because their EULAs (End User License Agreements) inform users of the software's mode of operation.
Is having PDFCastle installed on my computer dangerous?
Unwanted applications typically possess undesirable or harmful capabilities (e.g., generating redirects, displaying ads, gathering data, etc.). Additionally, these apps often infiltrate devices in bundles. The presence of unwanted software is associated with system infections, privacy issues, financial losses, and identity theft.
Will Combo Cleaner help me remove PDFCastle unwanted application?
Yes, Combo Cleaner can scan computers and eliminate installed unwanted/malicious apps. Keep in mind that manual removal (unaided by security software) might not be an ideal solution. In some cases, after an application has been manually removed – various remnants (files) stay hidden within the system. What is more, the remaining components might continue to run and cause issues. Therefore, it is essential to eliminate undesirable software thoroughly.
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