Home Malware Programs Potentially Unwanted Programs (PUPs) PDFster

PDFster

Posted: November 27, 2017

Threat Metric

Ranking: 14,972
Threat Level: 8/10
Infected PCs: 5,441
First Seen: January 28, 2022
Last Seen: March 10, 2025
OS(es) Affected: Windows

PDFster is a potentially unwanted browser extension by Tersertude Ltd that affects the Chrome browser and other versions based on the Chromium platform. PDFster has its own domain located at thepdfster.com, which contains a link to the extension’s page on the Google Chrome Web store. While PDFster claims to offer a specialized search engine that only searches the Web for PDF files, in reality, PDFster has a very little functionality. Once the extension is installed in Chrome, the users get a new button in their top menu bar. Clicking on it brings up a new search box. Using this new search engine simply redirects the search through search.yahoo.com and brings up the same results page you would get in the Yahoo Search, only with a modified URL.

The results do not include any PDF files, as the extension suggests and PDFster does not include specialized PDF search functionality, which puts it in the gray area of Potentially Unwanted Programs (PUPs). There is no way to know for sure how your search queries are treated, whether they are stored by the people who run PDFster and whether this information is sold to any third parties or not. The simple fact that the program has none of the functionality it claims to have is already a pretty big red flag. Thankfully, PDFster does appear in the Chrome extension menu and can be removed from there even manually. Users also should take note that PDFster also might come bundled with other software, in what is called software bundle installers.

PDFster is very likely an offshoot of the PDF Baron – another potentially unwanted browser extension distributed by Tersertude Ltd, which we have covered previously.

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