Saturday, November 4, 2017

CrunchyRoll hack delivers malware


Introduction

There's a Reddit post today with a PSA (Public Service Announcement) about Crunchyroll, a website that offers anime streaming, being hacked:

PSA : Don't enter crunchyroll.com at the moment, it seems they've been hacked.

As mentioned before, Crunchyroll offers anime streaming, and in their own words:
Enjoy your favorite anime & manga at the speed of Japan

The German Crunchyroll team has additionally issued the following warning:



The official CrunchyRoll Twitter account has tweeted the following:



If you are only interested in how to remove this malware, scroll down to the disinfection/removal section, or click here.


Update:  CrunchyRoll has announced, after a few hours, that the issue is resolved:



However, I still advise you to scroll over to the disinfection or removal section. Any questions, feel free to leave a comment, or contact me on Twitter.



Analysis

So, what happens when you visit the CrunchyRoll website? Curently, you get a message the website has encountered an error:

Figure 1 - CrunchyRoll error page

Earlier today, the CrunchyRoll website was showing the following:

Figure 2 - Likely hacked CrunchyRoll website (Image source)


While the CrunchyRoll team claims it was a DNS hijack, I have (so far) found no evidence as to the validity of this claim, and it rather appears someone was able to hack the website.

Either way, while this is bad, CrunchyRoll took swift action by taking down the website, and an investigation is under way.

What happens if you click the 'Download now' button? A new file, called CrunchyViewer.exe, will be downloaded from the following IP address:

109.232.225[.]12

This IP appears to have hosted fake antivirus software or similar in the past:

Figure 3 - Older resolutions (2010)

The newly download file is seemingly the legitimate CrunchyViewer or Crunchyroll, but, near the end of the file, there is a chunk of Base64 encoded data appended, as seen in Figure 4:

Figure 4 - base64 encoded data (click to enlarge)

Using a Base64 decoder, we get a new file, called svchost.exe. This binary will place a copy of itself in the current user's %appdata%\roaming folder, for example:

C:\Users\Yourusername\AppData\Roaming\svchost.exe

This file will periodically call to its C2, or command-and-control server, and wait for any commands:

145.239.41[.]131

Currently, it does not appear the C2 responds on that specific port (6969), however, it is online.

There are claims the malware will additionally install ransomware - I have not observed this behaviour, but it is definitely possible once the C2 sends back (any) commands. More likely, it is a form of keylogger - malware that can record anything you type, and send it back to the attacker.

Update: It appears however, thanks to ANY.RUN for the heads-up, (analysis here) that the malware actually downloads Meterpreter, which is a default Metasploit payload.

More information about Meterpreter can be found here, but basically, it can be viewed as a backdoor, as it allows the attacker to completely control your machine. However, it does appear the C2 server only downloaded Meterpreter for a limited amount of time - as port 6969 only responded within a specific time-frame.

Note that the disinfection or removal tips are still applicable in this case.

Svchost.exe will also create an autorun entry:

Figure 5 - newly created run key (click to enlarge)

This basically means the malware will start every time you (re)boot or restart the machine.

Just for fun, it appear that the miscreant's name, or the person responsible for creating the malware is named Ben, as appears from the debug paths:

C:\Users\Ben\Desktop\taiga-develop\bin\Debug\Taiga.pdb 
c:\users\ben\source\repos\svchost\Release\svchost.pdb

Taiga is 'A lightweight anime tracker for Windows'. This does not mean they are involved, but rather that 'Ben' has decided to include Taiga in the package.

Update: the developer of Taiga has included a fix for 'CrunchyViewer':
https://github.com/erengy/taiga/issues/489

Thus, if you now update or install the official Taiga application, it will prompt you if the malware is found, and is able to remove it.


Disinfection/Removal

Disinfection is rather straightforward:


  • Remove the malicious "Java" Run key, by opening Regedit, and browsing to:
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • Delete the 'Java' key;
  • Reboot your machine;
  • Remove the malicious binary, by navigating to:
    %appdata%\Roaming (for exampleC:\Users\Yourusername\AppData\Roaming\)
  • Delete the 'svchost.exe' file.
  • Perform a scan with your installed antivirus product;
  • Perform a scan with an online antivirus, which is different from the one you have. Alternatively, perform a scan with Malwarebytes.
  • Change all your passwords if possible. Better be safe than sorry.



Prevention


Prevention  advise in general, which also pertains to CrunchyRoll's compromise:

  • Install an antivirus;
  • Keep your browser up-to-date;
  • Install NoScript if you have Firefox;
  • Install a 'well-rounded' ad-blocker, for example uBlock Origin (works with most browsers);
  • If a website you visit frequently suddenly looks completely different, or urges you to download whatever, be safe rather than sorry, and leave the website.
  • Additionally, try to Google or use social media to verify if anyone else is experiencing the same issue.
In this particular case or incident, you may also want to block the two IP addresses as described in this blog post, by adding them in your firewall, or adding them in your hosts file, like so:

127.0.0.1 109.232.225.12
127.0.0.1 145.239.41.131

For more information on how to do that, read:
How to Edit Your Hosts File on Windows, Mac, or Linux

Note that there needs to be at least a space between 127.0.0.1, and the address you want to block.



Conclusion

This hack shows that any website or organisation is, in theory, vulnerable to someone hijacking the website, and consequently download and install malware on a user's machine.

While it is uncertain what exactly happened, CrunchyRoll took correct action by taking the website down not too long after. At this point, it is best to monitor their Twitter account, and/or wait for an official statement.

If you have not executed the file, you should be safe. Simply delete the downloaded file.

Note that I can't speak for any second-stage payload that may have been downloaded in the early stage of the attack - however; when I investigated shortly after, I didn't observe any secondary malware.

Update: the second-stage payload was the default Meterpreter by Metasploit. Updated analysis above. This does not affect or change the disinfection or removal steps.

Follow the prevention tips above to stay secure. Any questions or feedback? Feel free to leave a comment, or reach out to me on Twitter.



IOCs