Additional analysis by Lion Gu
Whenever a threat is “localized” to a specific region, it’s a sign that attackers believe there is money to be made. Ransomware has made millions of dollars around the world, and it looks like it’s poking its nose into a new part of the world: China. However, the initial foray into this market made several mistakes.
We recently came across multiple samples of what appeared to be Chinese-language ransomware. We detect this as Ransom_SHUJIN.A. All of these samples could be decompressed into the same executable file. While this is not the first time that Chinese-language ransomware has been found, this may be the first time that one used simplified Chinese characters. This character set is favored for use in mainland China. As of this writing, the infection vector of this attack is not yet known.
Once this ransomware is run, it displays the following message:
Figure 1. Warning message from ransomware
The language here is similar to those used in other ransomware threats – that the user’s files are being encrypted, with a count of the total number of files encrypted and the size of the encrypted files.
The ransom note is comparable to those used in other ransomware attacks, with instructions to download the Tor browser to connect to the attacker’s dark web site.
Figure 2. Ransom note and other instructions (click to enlarge)
The language of the note suggests that the author is someone fluent in Chinese; the instructions have also been modified to suit local conditions – Baidu instead of Google is recommended as the way to find the Tor browser; the author also mentions the use of a virtual private network (VPN) or proxy to get around the blocks imposed on Tor usage in China.
The instructions on this dark web site are similar to those found in other ransomware attacks. The screenshot below has been annotated with the used URLs:
Figure 3. Dark web site used by SHUJIN ransomware, with annotations
These URLs lead to:
- hxxp://eqlc75eumpb77ced[.]onion/Decrypt.exe – updated copy of Ransom_SHUJIN.A
- hxxp://eqlc75eumpb77ced[.]onion/GetMKey.JPG – step-by-step instructions
- hxxp://eqlc75eumpb77ced[.]onion/btc/ – bitcoin tutorials
- hxxp://eqlc75eumpb77ced[.]onion/btc/help.html – bitcoin tutorials
- hxxp://eqlc75eumpb77ced[.]onion/DeFile.JPG – more instructions
However, some things about the SHUJIN ransomware don’t quite add up. Throughout this post we called this attack a ransomware attack and not a crypto-ransomware attack. Why? Because despite the language in the note, no encryption actually takes place.
Similarly, the usage of bitcoin and Tor for ransom payments is unusual. This method requires some technical knowledge to carry out, both to use Tor and acquire bitcoins. We have seen mobile ransomware in China before – but in these cases Alipay (a popular local payment solution) was abused, with the attackers reachable via a QQ number.
SHUJIN’s lack of familiarity with the Chinese Internet landscape suggests attackers located outside of the country. We believe that this is the case despite the use of good Chinese grammar. Down the road, we may see these attacks improve and target Chinese users more effectively, allowing them to pay in a manner that they are more accustomed to.
The sample related to this attack has the following SHA1 hash: