Download Sentinel

Warns for potentially harmful downloads.

DOWNLOAD SENTINEL Every time you download a file, Download Sentinel quietly runs a set of quick checks. No single check is proof of danger on its own; instead, each one adds or removes a few "trust points," and the final total decides whether the file looks Safe, Questionable, Suspicious, or Malicious. 1. Does anyone else already know this file/site is bad or safe? Reputation scan (VirusTotal): Checks if security companies around the world have already flagged this exact download link as malicious, and how long it's been known about. A link seen and confirmed clean for weeks is trusted more than one that appeared an hour ago. DNS blocklist check (Quad9): Checks the website's address against known lists of malicious domains — similar to a phone number being flagged as a scam caller. 2. Is the website itself trustworthy? Domain & website-ending checks: Some website names and endings (like certain unusual .xyz-style suffixes) are used far more often for scams than legitimate ones, so a match lowers trust. How new is the website?: Scam sites are often thrown together and abandoned quickly. A domain registered only days ago is treated with more suspicion than one that's existed for years. Look-alike names: Catches tricks like fake Microsoft/Apple/PayPal-style addresses, confusable letters (e.g. "m1crosoft"), or oddly long chains of sub-addresses designed to fool the eye. 3. Is the file itself hiding something? File type vs. label mismatch: If a site claims to be sending a photo but is actually sending a program, that mismatch is a red flag. Disguised file endings: Catches tricks like "invoice.pdf.exe" — a program pretending to be a harmless document by hiding its real ending. Raw scripts: Bare scripts are a common way to sneak malicious commands past you. A home user has little to no reason to download scripts. Unusually large files: Very large files can't be fully scanned by reputation services, so they're flagged as "check this yourself before trusting it." 4. Is the connection itself risky? Unencrypted connections: Downloads sent without the padlock (HTTPS) can be tampered with in transit. Raw numeric addresses: Legitimate services almost always use a proper website name, not a bare set of numbers as the address. Risky hosting: Some free/throwaway hosting platforms are disproportionately used to distribute malware, so files served from them are treated with extra caution. WHY ONLY SHOW A WARNING There are three reasons. First not blocking but showing a post download warning (which can be surpressed when it is probabaly safe in the options panel) also provides a 100% guarantee that it will never block a download you really need (e.g. a ticket for a concert in password protected zip-file). Secondly for the Virus Total results Download Sentinel waits maximum of 2 seconds to get the VT-rating. Small executables and scripts will be downloaded in these 2 seconds already. Third reason there are some tricks to start a download as pdf or zip and rename it when download completed as script or executable. Using the post download warning makes this extra heuristics check possible. HOW DOES THE WARNING PAGE WORK? The warning page shows a risk score based on what VirusTotal knows about the download address. The file itself is never sent to VirusTotal, which is better for your privacy and gives a faster result. After checking the results, you can choose to proceed, or to look up the download at VirusTotal (when it is known there), or at Hybrid Analysis for a free scan with Metadefender and Crowdstrike (when it is not known at VirusTotal yet). OPTIONS PANEL A false positive reduction level can be set to reduce unnecessary warnings for well-known safe software. Up to 12 trusted websites can be whitelisted so downloads from those sites are never checked. You can also set a minimum confidence level to skip the warning automatically when a download is probably safe (default is +80%). The background color and the title of the warning page can be changed to your personal preference. Open Source: https://github.com/Kees1958/DownloadSentinel