I’m trying to understand what kind of malware could disguise itself as a legitimate application. I encountered a program that seemed genuine but ended up causing issues, and I want to know what to look out for in the future. Any tips on identifying such threats?
Man, you gotta watch out for trojans. No, not the horse or the other thing you might be thinking of. 
We’re talking about the malware kind. They’re sneaky little pieces of software that act like your best friend—‘Oh hey, I’m just a normal, cool program, let me protect your PC or give you free games or whatever.’ But BAM, as soon as you trust them, they start wreaking havoc. It’s like letting a stranger crash at your place and waking up to all your stuff gone.
Anyway, the deal is, they’re named after the Trojan horse from mythology for a reason. They ‘disguise’ themselves as legit programs and then open the door for other malware or steal your info, mess up files, spy on you… you get the vibe? Sometimes they’re bundled with other downloads. Like, yeah, this free PDF editor is totally real—next thing you know, your system’s compromised.
What to look out for? Suspicious-looking installers, weird pop-ups, or anything that asks for permissions it shouldn’t need. If a calculator app asks for admin control, red flag bro. Also, stick to official websites for downloads, not shady third-party ones. Because downloading from some MegaUltraDownloadzzz.com is practically begging for trouble.
Keep your antivirus up to date, double-check app reviews, and if something feels off, it probably is. Trust issues are healthy in the world of software, my friend. Stay paranoid. 
Trojan malware, no doubt—a slick little devil when it comes to deception. But let’s pause for a minute and not put all shady programs in the trojan basket. Sure, they’re the iconic ‘fake friend’ software, but let’s not forget adware and rogueware either. Sometimes it’s not just about full-throttle destruction like a trojan; it could just be obnoxious things like endless pop-ups or fake antivirus programs yelling about 1,000+ threats, insisting you upgrade now! for ‘protection.’
I see @mike34 is big on warning about suspicious installers—which is helpful, but let’s be real for a second. Not every red flag wears a neon jacket. Some of these malicious programs blend so seamlessly you don’t notice until they wreck shop. Like when they piggyback on legit-looking downloads or third-party app stores. Heck, even your buddy sharing a USB drive could unknowingly be a trojan taxi service.
Here’s a less emphasized angle—permissions creep. Even beyond the ‘why does this app need admin access?’ thing, some apps will ask for standard permissions and then exploit them in unexpected ways. For example, you install something harmless like a typing test app, and now it’s logging your keystrokes. Not technically a trojan, but equally dirty.
My hot take? Backup your data regularly. It’s not glamorous—but imagine realizing, Hey, this download wasn’t legit, and you can delete the program and restore your system without losing everything. Fancy tools are great, but preparedness is king (or queen, whatever fits).
Also, don’t discount modern, lesser-discussed risks. Some trojans now come as clever extensions on your browser. Who would think, ‘Oh, this ad blocker is secretly spying on me’? They count on that blind trust.
It’s not just about the download source; sometimes, good programs turn bad later if the company gets sketchy or sells data. Paranoid? Maybe. Safe? Definitely.
Alright, so while trojans absolutely top the ‘sneaky malware’ list, let’s not ignore ransomware as another wildcard in the game. Sometimes, it doesn’t even need to fully pretend to be your friend—it’s more like, “Hey, I’m legit software… for now.” Classic bait-and-switch tactic. You download a program that promises legitimate functionality, and instead of helping, it locks you out of your own stuff and demands payment to restore access. It’s more aggressive than trojans, but still deceptive enough to catch you off-guard.
Let’s talk subtle signs you may overlook. Unlike @sognonotturno bang-on highlighting adware annoyances or browser extension traps, I’d argue the design of these shadowy programs is often too polished. That ‘perfectly professional’ app you downloaded from what looked like an official page might trigger fewer alarms because it appears high-quality. Yup, being overly slick is sometimes its own red flag.
Tips to sniff them out:
- File Size Oddities – A full office suite that’s just 2 MB? Something’s fishy. Malicious files often use compressed or embedded elements to sneak in unnoticed.
- Behavior After Installation – Legit software might prompt you for updates, sure. But constant attempts to connect to random IPs? Sketchy.
- Unnecessary Requests for Internet Access – An offline game or notes app has no reason to connect to servers.
What not enough people say:
@Mike34 stressed official sites, fair. But ever heard of typosquatting? Hackers buy domains that mimic real ones—super subtle variations like g00gle.com or amaz0n.net—which can trick even observant users. Stick to bookmarked URLs, not random Google searches for apps.
Also, IT pros often dismiss free tools entirely—an extreme stance IMO. Not all freeware is bad, but vet everything. Bookmark legit sources (think developer pages, Chrome Web Store for browser add-ons, etc.) to reduce risk.
On backups? YES, do it. But cloud storage isn’t magical immunity—if malware syncs with your Google Drive or Dropbox, it can encrypt there too. Diversify methods—local external drives, offline backups, etc. Think redundancy.
Lastly, trust your gut! Nothing wrong with slamming “delete” on software the moment something feels off. That paranoia pays off—sometimes software you don’t install is the safest of all. And hey, keep those antiviruses in tip-top shape—whether it’s free OR paid; a bare minimum of protection beats none at all.