autoupdater and connection temp.sh

PeterJones

Notepad++ v8.8.4 (64-bit)
Build time: Aug 4 2025 - 18:01:28

and

gup.exe : 807,936 byes, created Sunday, August 10, 2025
libcurl.dll : 818,688 bytes, created Sunday, August 10, 2025
notepad++.exe : 8,699,392 bytes , created Sunday, August 10, 2025

Hmm… Those all match with what I see for a correct Notepad++ v8.8.4.

I don’t know why you would see curl.exe rather than curl.dll, or the strange URL and AutoUpdater.exe, because I really wouldn’t expect that as normal behavior. I think you’re going to have to wait for @xomx or someone else more knowledgable than I am about the updater process, because the files look right to me, but the activities seem weird, to me.

xomx

@soft-parsley

Unfortunately, I’ve a bad news for you, if you didn’t somehow initialize all of this yourself, your comp is no longer yours…

t e m p . s h seems to be a kind of non-permanent storage, anyone can use it:

temp.sh.png

Notepad++ doesn’t distribute/use curl.exe binary, it uses the curl-library functionality via “C:\Program Files\Notepad++\updater\libcurl.dll” for the N++ updater GUP.exe. And of course N++ never uses such an anonymous storage place.

Also you should check the digital signatures of your N++ binaries like:

Moreover, nowadays it isn’t possible to download or update to N++ v8.8.4, as this specific version was withdrawn because it contained regressions.

donho

@soft-parsley
Could you provide your gup.xml file from C:\Program Files\Notepad++\updater\ directory?

John Smith 4

@donho I see in v8.8.8 release there was an issue addressed with WinGup. Could you elaborate what caused this behavior?

donho

@John-Smith-4

I see in v8.8.8 release there was an issue addressed with WinGup. Could you elaborate what caused this behavior?

Unfortunately I can’t provide more facts than what we already know.
We are not aware of any confirmed exploitation of this vulnerability in the wild.
The fix in v8.8.8 is the best I could do to address the issue of WinGUp being hijacked.

SammyBolt

@donho

Thank you for all the work you do, I’m a huge fan of Notepad++, I wanted to confirm a few details due to the heavy usage of Notepad++ in my environment:

Regarding the WinGup fix in v8.8.8, Was the temp.sh (or similar) exfiltration vector reported in v8.8.4 possible on a clean, official installation of Notepad++?

Was administrative privileges on the Windows computer where 8.8.4 is install required to exploit the vulnerability?

You mentioned the fix landed in v8.8.8, but can you confirm if this vulnerability was introduced specifically in v8.8.4 (due to changes in the updater), or were versions prior to 8.8.4 (like 8.8.2/8.8.3) also susceptible to this specific gup.exe hijacking technique? What about 8.8.5-8.8.7?

For users currently running v8.8.4 who want to verify they haven’t been impacted before updating: Aside from monitoring network traffic for temp.sh, are there specific things we can check for, like modifications to the update xml file or other modified files/logs in the program directory?

xomx

@SammyBolt

From what I know, this is not directly about a bug/vulnerability in the N++ ecosystem, but rather a preventive security fortification against possible attacks independent of the N++. Namely against the DNS spoofing type of attacks. The upcoming v8.8.9 will bring another such fortification.

donho

@SammyBolt said in autoupdater and connection temp.sh:

Regarding the WinGup fix in v8.8.8, Was the temp.sh (or similar) exfiltration vector reported in v8.8.4 possible on a clean, official installation of Notepad++?

The temporary fix prevents the hijacking attempts that redirect to the domain other than github.com. However, it cannot protect against malware that is hosted on github.com.

The full fix will be included in the upcoming version, as mentioned below.

You mentioned the fix landed in v8.8.8, but can you confirm if this vulnerability was introduced specifically in v8.8.4 (due to changes in the updater), or were versions prior to 8.8.4 (like 8.8.2/8.8.3) also susceptible to this specific gup.exe hijacking technique? What about 8.8.5-8.8.7?

We still cannot determine the exact method used by the attacker. But it is not a case of “a vulnerability introduced in version X”.

For users currently running v8.8.4 who want to verify they haven’t been impacted before updating: Aside from monitoring network traffic for temp.sh, are there specific things we can check for, like modifications to the update xml file or other modified files/logs in the program directory?

I do not have complete information to provide specific advice. However, here’s an article from a security expert who appears to have investigated this issue:
https://doublepulsar.com/small-numbers-of-notepad-users-reporting-security-woes-371d7a3fd2d9

My suggestion is download & install v8.8.8 manually from the official website.
The upcoming release v8.8.9 will be available in a few days. In this release the code signing certificates will be verified on the downloaded binary before update installation.
Then please update to v8.8.9, in which the vulnerability is fully addressed.

donho

FYI:
Security Update - Resolution of Notepad++ Update Server Compromise
https://notepad-plus-plus.org/news/hijacked-incident-info-update/

xomx

Seeing reactions all over the net to this attack, I’d like to try to clear some of the frequently asked questions: “Was my PC vulnerable/attacked/compromised too?” usually followed by “What should I do now?”. And also the common “Is this a Notepad++ fault or what?”. And remember, all the following is my personal view only. Also don’t ask me please for more attack details, the investigation is still ongoing and @donho will surely disclose more whenever/if it’ll be possible to do so.

Before I try to answer these questions, I have to explain 1st a little the N++ auto-update mechanism, as with every successful attack the attackers searched & found a weak-spot and this time it was the N++ automatic updates mechanism.

N++ auto-update simply works as:

you installed a N++ version X.Y.Z, date of that installation is stored into a N++ config file
when that installed N++ app is launched after a predefined period of time (I think, the default is 14 days), it issues a net-request to the N++ (compromised) server about a possible newer version than the current X.Y.Z and gets a response (yes/no, together with a link to the possible new updated binaries/installer)
then the app is being updated (at exit or start of the N++ app, see the setting pics below)

More about that stuff e.g. here: https://github.com/notepad-plus-plus/notepad-plus-plus/issues/16759#issuecomment-3016024980

Now you can see the weakness, as the attackers were able to hack the N++ hosting provider server, they were also able to intercept/change the N++ updater answers from the PHP script running there and redirect these answers for specific IP addresses they were interested in.

Now to the questions:

Was my PC vulnerable too?
Only the users with this N++ setting ON could be affected:

and only if there was at least one real N++ version auto-update in the attack-window (Jun 2025 - 2nd of Dec 2025, which means N++ updates to v8.8.2 - v8.8.8). Note that N++ binaries (installers and portable archives) have not been compromised at all, they reside at the GitHub https://github.com/notepad-plus-plus/notepad-plus-plus/releases/
Was my PC attacked too?
Most probably not. This was a highly targeted “supply chain” type of attack against some East Asia orgs.
Was/is my PC compromised too? What should I do now?
The attackers attack was to collect/steal info one, so not a crypto-virus etc. (spreading and infecting your other files). But if you are in the theoretically affected group of users (see above), I’d highly recommend:

full AV scan of your PC (if you don’t have any, you can e.g. use this offline MBAM: https://downloads.malwarebytes.com/file/mb5_offline )
manual re-installation to the latest Notepad++ v8.9.1
changing/rotating all your passwords used in that attack-window on/from your PC

Is this a Notepad++ fault or what?
Yes, definitely. I’m saying this even if the attack target was not primarily the N++ app-code but an external hosting server. Once that server had been compromised (well, this itself was not a N++ fault), attackers could attack the N++'s distribution network/mechanism without further obstacles, which is just wrong (nowadays).

All I can say to defend N++ here is that it’s always easy to be wise after something…

Unfortunately, in the future, it’ll be necessary to devote the precious time of active contributors to the N++ project, instead to the app’s own functionality, also more to its security. So, at this point, I’d like to invite any of you using the N++ who are good at security, to also contribute a little of your experience and time for keeping this app up-to-date from a security POV. It’s opensource SW folks, not a magic box programming and maintaining itself.

xomx

Addendum to the points 2. & 3. above - even if you’re not to Reverse Engineering much, just follow the link and skip it to the ending “Indicators of compromise” part, where are some common markers that could help you decide whether or not your comp has been compromised:

https://www.rapid7.com/blog/post/tr-chrysalis-backdoor-dive-into-lotus-blossoms-toolkit/