# OSX/Proton spreading again through supply‑chain attack

**welivesecurity.com/2017/10/20/osx-proton-supply-chain-attack-elmedia/**

October 19, 2017

Our researchers noticed that the makers of the Elmedia Player software have been distributing a version of their app
trojanized with the OSX/Proton malware.

[ESET Research](https://www.welivesecurity.com/author/esetresearch/)
20 Oct 2017 - 01:56AM

Our researchers noticed that the makers of the Elmedia Player software have been distributing a version of their app
trojanized with the OSX/Proton malware.

[On 19 October 2017, ESET researchers noticed that Eltima, the makers of the Elmedia Player software, were distributing](https://www.eltima.com/)
[a version of their application trojanized with the OSX/Proton malware on their official website. ESET contacted Eltima as](http://www.virusradar.com/en/OSX_Proton)
soon as the situation was confirmed. Eltima was very responsive and maintained an excellent communication with us
throughout the incident.


-----

Timeline

2017-10-19 : Trojanized package confirmed
2017-10-19 10:35am EDT: Eltima informed via email
2017-10-19 2:25pm EDT: Eltima acknowledged the issue and initiated remediation efforts
2017-10-19 3:10pm EDT: Eltima confirms their infrastructure is cleaned up and serving the legitimate applications
again
2017-10-19 10:12am EDT: [Eltima publishes an announcement about the event](https://www.eltima.com/blog/2017/10/elmedia-player-and-folx-malware-threat-neutralized.html)
2017-10-20 12:15pm EDT: Added references to Folx that was also distributed with the Proton malware

_Note: This blog was initially_ _posted despite our research being incomplete. Hence, this information is preliminary and the_
_blogpost will be updated as new facts emerge._

## Am I compromised?

ESET advises anyone who downloaded Elmedia Player or Folx software recently to verify if their system is compromised
by testing the presence of any of the following files or directories:

/tmp/Updater.app/
/Library/LaunchAgents/com.Eltima.UpdaterAgent.plist
/Library/.rand/
/Library/.rand/updateragent.app/

If any of them exists, it means the trojanized Elmedia Player or Folx application was executed and that OSX/Proton is
most likely running.

If you have downloaded that software on October 19th before 3:15pm EDT and run it, you are likely compromised.

As far as we know, the trojanized version of the application was only downloadable from the Eltima website, between
08:00 and 15:15 EDT on 19 October 2017. The built-in automatic update mechanism seems unaffected.

## What does the malicious payload do to a compromised system?

OSX/Proton is a backdoor with extensive data-stealing capabilities. It gains persistence on the system and can steal the
following:

Operating system details: hardware serial number (IOPlatformSerialNumber), full name of the current user,
hostname, System Integrity Protection status (csrutil status), gateway information (route -n get default | awk
‘/gateway/ { print $2 }’), current time & timezone
Browser information from Chrome, Safari, Opera and Firefox: history, cookies, bookmarks, login data, etc.
Cryptocurrency wallets:

Electrum: ~/.electrum/wallets
Bitcoin Core: ~/Library/Application Support/Bitcoin/wallet.dat
Armory: ~/Library/Application Support/Armory
SSH private data (entire .ssh content)
[macOS keychain data using a modified version of chainbreaker](https://github.com/n0fate/chainbreaker/)
Tunnelblick VPN configuration (~/Library/Application Support/Tunnelblick/Configurations)
GnuPG data (~/.gnupg)
1Password data (~/Library/Application Support/1Password 4 and ~/Library/Application Support/1Password 3.9)
List of all installed applications.

### How do I clean my system?

As with any compromise of an administrator account, a full OS reinstall is the only sure way to get rid of the malware.
Victims should also assume at least all the secrets outlined in the previous section are compromised and take appropriate
measures to invalidate them.

## Supply-chain attack revisited on the Mac


-----

Last year, the Mac Bittorrent client Transmission was abused twice to spread malware, first the OSX/KeRanger
[ransomware followed by OSX/Keydnap password stealer. Then this year, the Handbrake video-transcoder application was](https://www.welivesecurity.com/2016/08/30/osxkeydnap-spreads-via-signed-transmission-application/)
[found bundled with OSX/Proton.](https://blog.malwarebytes.com/threat-analysis/mac-threat-analysis/2017/05/handbrake-hacked-to-drop-new-variant-of-proton-malware/)

Today, ESET discovered another popular Mac software package being used to spread OSX/Proton: Elmedia Player, a
media player that reached the 1,000,000 users milestone this summer:

## Technical analysis

OSX/Proton is a RAT (Remote Access Trojan) sold as a kit on underground forums. It was very briefly documented by
[Sixgill earlier this year and then further analyzed by Thomas Reed at MalwareBytes,](https://www.cybersixgill.com/proton-a-new-mac-os-rat/) [Amit Serper at CyberReason and](https://www.cybereason.com/labs-blog/labs-proton-b-what-this-mac-malware-actually-does)
[Patrick Wardle at Objective-See.](https://objective-see.com/blog/blog_0x1F.html)

In the current case of Eltima trojanized software, the attacker built a signed wrapper around the legitimate Elmedia Player
and Proton. In fact, we observed what seems to be real-time repackaging and signing of the wrappers, all with the same
valid Apple Developer ID. See the history of currently known samples below. Eltima and ESET confirmed they are working
with Apple to invalidate the Developer ID used to sign the malicious application. (Apple revoked the certificate.)

(timestamps are all in EDT timezone)

Clean application:

**Timestamp** **Developper ID** **SHA-1**


-----

**Timestamp** **Developper ID** **SHA-1**


Timestamp=Jul 24,
2017, 4:56:24 AM

Trojanized application:


Authority=Developer ID Application:
ELTIMA LLC (N7U4HGP254)

```
0603353852e174fc0337642e3957c7423f182a8c

```

**Timestamp** **Developper ID** **SHA-1 (dmg file)**


Timestamp=Oct 19,
2017, 8:00:05 AM

Timestamp=Oct 19,
2017, 12:22:24 PM

Timestamp=Oct 19,
2017, 2:00:38 PM


Authority=Developer ID Application:
Clifton Grimm (9H35WM5TA5)

Authority=Developer ID Application:
Clifton Grimm (9H35WM5TA5)

Authority=Developer ID Application:
Clifton Grimm (9H35WM5TA5)

```
e9dcdae1406ab1132dc9d507fd63503e5c4d41d9

```

First, the wrapper launches the real Elmedia Player application stored in the Resources folder of the application:

And finally extracts & launches OSX/Proton:

As seen in previous cases, OSX/Proton shows a fake Authorization window to gain root privileges:


-----

### Persistance

OSX/Proton ensures persistence by adding a LaunchAgent for all users when the administrator types their password. It
creates the following files on the system:

/Library/LaunchAgents/com.Eltima.UpdaterAgent.plist
/Library/.rand/updateragent.app


1

2

3

4

5

6

7

8

9


$ plutil -p /Library/LaunchAgents/com.Eltima.UpdaterAgent.plist

{

"ProgramArguments" => [

0 => "/Library/.rand/updateragent.app/Contents/MacOS/updateragent"

]

"KeepAlive" => 1

"RunAtLoad" => 1

"Label" => "com.Eltima.UpdaterAgent"

}


### Backdoor commands

As mentioned at the beginning of the post, OSX/Proton is a backdoor with extensive information stealing capabilities. The
backdoor component we observed supports the following commands:

`archive` Archive files using zip


-----

`force_update` Self-update with digital signature validation
```
 phonehome

```
`remote_execute` Execute the binary file inside a .zip file or a given shell command

`tunnel` Create SSH tunnel using port 22 or 5900

`upload` Upload file to C&C server

## C&C server

Proton uses a C&C domain that mimics the legitimate Eltima domain, which is consistent with the Handbrake case:

**Legitimate domain** **Proton C2 domain**

Eltima eltima.com eltima[.]in

Handbrake handbrake.fr handbrakestore[.]com

handbrake[.]cc

## IOCs

URL distributing the trojanized application at the time of discovery:

hxxps://mac[.]eltima[.]com/download/elmediaplayer.dmg
hxxp://www.elmedia-video-player.[.]com/download/elmediaplayer.dmg
hxxps://mac.eltima[.]com/download/downloader_mac.dmg

### C&C servers

eltima[.]in / 5.196.42.123 (domain registered 2017-10-15)

### Hashes


**Path** **SHA-1**


**ESET**
**Detection**
**name** **Description**


Elmedia
Player.app/Contents/Resources/.pl.zip

Elmedia
Player.app/Contents/MacOS/Elmedia
Player


`9E5378165BB20E9A7F74A7FCC73B528F7B231A75` multiple
threats

`10A09C09FD5DD76202E308718A357ABC7DE291B5` multiple
threats


`C9472D791C076A10DCE5FF0D3AB6E7706524B741` OSX/Proton.D Launcher
(or wrapper)

`30D77908AC9D37C4C14D32EA3E0B8DF4C7E75464` OSX/Proton.D Launcher
(or wrapper)


ZIP archive
with the
Proton
malware
and Python
scripts

ZIP archive
with the
Proton
malware
and Python
scripts


Updater.app/Contents/MacOS/Updater `3EF34E2581937BABD2B7CE63AB1D92CD9440181A` OSX/Proton.C Proton
malware,
not signed


-----

**Path** **SHA-1**


**ESET**
**Detection**
**name** **Description**


`EF5A11A1BB5B2423554309688AA7947F4AFA5388` OSX/Proton.C Proton
malware,
not signed

Hat tip to Michal Malik, Anton Cherepanov, Marc-Étienne M. Léveillé, Thomas Dupuy & Alexis Dorais-Joncas for their work
on this investigation.

20 Oct 2017 - 01:56AM

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