One of the researchers posted links to both malicious dmgs.

[1]: https://twitter.com/claud_xiao/status/706563279355645953

Maybe take a look around https://build.transmissionbt.com/ - but then again maybe the svn repo wasn't compromised? I tried a "svn diff svn://svn.transmissionbt.com/Transmission/tags/2.90 svn://svn.transmissionbt.com/Transmission/tags/2.91" and didn't see anything suspicious on a fast scroll-through

Side topic: probably not a good idea to expose Jenkins externally, especially if you don't keep Jenkins up-to-date all the time (for transmission bt it is up-to-date right now). This Jenkins probably contain the key to the svn server, so if someone finds a hole...

>Side topic: probably not a good idea to expose Jenkins externally

Jenkins (and CI in general) can be a very weak point. This was posted on Hacker News a while back https://github.com/samratashok/ContinuousIntrusion

Very useful demonstration. thanks for sharing.

> Jenkins probably contain the key to the svn server

Why should it? For open-source software build-server can even be ran by a third party.

I am not following your comment here. Most Jenkins setup use global credentials or use the server-side config file like .ssh/config, .gitconfig link.

But ideally there are no credentials because Jenkins doesn't need to push code to the repo (and can clone the pubically available code).

But it might need to push new (binary) updates if the master/deploy branches gets updated or a commit contains a specific tag.

As far as I know, only the binary was updated.

I'd be interested to hear, though, how it got compromised after all.

Yeah, that makes sense. Build servers are one of the weakest links in distributing software. That's why this exists and I'm glad it's making progress:

https://reproducible-builds.org

And even if you sign updates, the key management for doing that is usually centralized, which can be bad:

http://arstechnica.com/security/2016/02/most-software-alread...

I do not think it was the build server, though. According to this analysis[1], the developer used a different key to sign the build (all Mac apps need to be signed or the default behavior is to reject that App. You can permanently disable this behavior in settings, or just for on app by holding control while opening the App, which a lot users who use transmission probably do because not all legitimate Apps are signed). Anyways, since the app was signed by a third party's certificate (which was approved by Apple), chances are only the website was compromised. If the build server had been compromised, the attack would have had access to the developer's certificate and they would most likely have used that.

[1]: http://researchcenter.paloaltonetworks.com/2016/03/new-os-x-...

Transmission, as an open source project, should probably evaluate another CI service such as Travis rather than run their own Jenkins services.

Here's an analysis of the malware - http://researchcenter.paloaltonetworks.com/2016/03/new-os-x-...

Copy/pasting the helpful parts of that article:

How to Protect Yourself

Users who have directly downloaded Transmission installer from official website after 11:00am PST, March 4, 2016 and before 7:00pm PST, March 5, 2016, may be been infected by KeRanger. If the Transmission installer was downloaded earlier or downloaded from any third party websites, we also suggest users perform the following security checks. Users of older versions of Transmission do not appear to be affected as of now.

We suggest users take the following steps to identify and remove KeRanger holds their files for ransom:

1. Using either Terminal or Finder, check whether /Applications/Transmission.app/Contents/Resources/ General.rtf or /Volumes/Transmission/Transmission.app/Contents/Resources/ General.rtf exist. If any of these exist, the Transmission application is infected and we suggest deleting this version of Transmission.

2. Using “Activity Monitor” preinstalled in OS X, check whether any process named “kernel_service” is running. If so, double check the process, choose the “Open Files and Ports” and check whether there is a file name like “/Users/<username>/Library/kernel_service” (Figure 12). If so, the process is KeRanger’s main process. We suggest terminating it with “Quit -> Force Quit”.

3. After these steps, we also recommend users check whether the files “.kernel_pid”, “.kernel_time”, “.kernel_complete” or “kernel_service” existing in ~/Library directory. If so, you should delete them.

You have a typo: "Applicaions". Usually not a problem but in this case it will say "No file/folder found" when it's just a typo.

Thanks. Fixed it. I only copy/pasted originally though :)

"It will then sleep for three days. Note that, in a different sample of KeRanger we discovered, the malware also sleeps for three days, but also makes requests to the C2 server every five minutes."

It's fascinating!

Isn't it possible to fire a takedown notice to that server? I mean KeRanger committed a felony and Amazon (assuming you mean Amazon's EC2 server) might react quickly if they realize what has happened. It might save a lot of computers from getting destroyed. As long as the server is somewhere in the Western world, it should not be a problem.

It's a "Command-and-Control" server (C&C or C2).

https://en.wikipedia.org/wiki/Command_and_control_%28malware...

I just learned that too. For me, C&C reminds me "Command and Conqueer" (the game).

https://en.wikipedia.org/wiki/Command_%26_Conquer

Thanks, I just realized it after reading Claud Xiao and Jin Chen's analysis, too. Apparently, this ransomware uses Tor to hide its origin.

Analysis: http://researchcenter.paloaltonetworks.com/2016/03/new-os-x-...

I liked the "We have ticket system." (in the screenshot of "README_TO_DECRYPT.txt").

They ask (only) 1 BtC as a ransom.

And they decrypt one file for free, to prove they can do it. Nice touch.

Screenshots of the web UI:

https://twitter.com/moyix/status/706577507965870080/photo/1

The server isn't on EC2, it's hosted on Tor. The malware uses an HTTP-to-TOR gateway service (onion.nu and onion.link) to pull down the encryption key and README file from one of three different hidden services. In theory you could try to get the gateways to block the connections, but I'm not sure they're likely to be cooperative.

Amazon's abuse teamight help, but the DMCA would not relevant unless you can show copyright infringement in this.

Nice. That matches what I'm seeing.