The cybercrime group that brought us Satan, DBGer and Lucky ransomware and perhaps Iron ransomware, has now come up with a new version or rebranding named “5ss5c”.
In a previous blog post, Satan ransomware adds EternalBlue exploit, I described how the group behind Satan ransomware has been actively developing its ransomware, adding new functionalities (specifically then: EternalBlue) and techniques with each run. Then, it appeared the group halted operations on at least the ransomware front for several months.
However, as it turns out, the group has been working on new ransomware – 5ss5c – since at least November 2019.
The following tweet got my attention:
— onion (@jishuzhain) January 12, 2020
After some quick checks, it appears this is a downloader for the 5ss5c ransomware, which is extremely reminiscent of how Satan ransomware operated:
|Figure 1 – 5ss5c downloader|
The malware will leverage certutil and even contains logging:
|Figure 2 – certutil logging|
It will download and leverage:
- Spreader (EternalBlue and hardcoded credentials);
- Mimikatz and what appears another password dumper/stealer;
- The actual ransomware.
The following hashes are relevant to this new variant:
Compilation timestamp: 2020-01-11 19:04:24
down.txt is, as mentioned, the downloader for the spreader module and for the actual ransomware:
Compilation timestamp: 2020-01-11 19:19:54
Compilation timestamp: 2020-01-11 19:54:25
Fun fact: file version information contains “TODO: 5SS5C Encoder“.
The compilation times are sequential, which makes sense – the downloader has been developed (and compiled) first, then the spreader and the actual ransomware.
Further indicators, such as hashes, URLs, file paths and so on will be posted at the end of this blog post.
5ss5c – still in development – and with oddities
There’s quite some curiosities that indicate 5ss5c is still in active development and stems from Satan ransomware, for example:
- There are several logs created, e.g. there is a file “C:Program FilesCommon FilesSystemScanlog” that simply logs whether IPC SMB is open/available;
- Certutil logging (successful download or not);
- There are several Satan ransomware artefacts;
- Other Tactics, Techniques and Procedures (TTP) align with both Satan (and DBGer), and slightly overlap with Iron:
- One of these is, for example, the use of multiple packers to protect their droppers and payloads.
- This time however, they decided to use both MPRESS and Enigma, and even Enigma VirtualBox! (Note: Enigma and Enigma VirtualBox are not the same – the latter is a virtualised packer and also referred to as EnigmaVM.)
However, there are quite some curiosities, one of them being what appear to be hardcoded credentials:
|Figure 3 – Hardcoded creds|
These hardcoded credentials will be leveraged in an attempt to connect to an SQL database with the xp_cmdshell command:
Curiously, we can identify the following data inside the ransomware in regards to the SQL database:
What else is new is, as mentioned before, the use of Enigma VirtualBox for packing an additional spreader module, aptly named poc.exe. This suggest they may be experimenting (poc often is an acronym for proof of concept).
This file will be dropped to C:ProgramDatapoc.exe and will run the following command:
cd /D C:ProgramData&star.exe –OutConfig a –TargetPort 445 –Protocol SMB –Architecture x64 –Function RunDLL –DllPayload C:ProgramDatadown64.dll –TargetIp
Now compare this to Satan ransomware’s command:
cmd /c cd /D C:UsersAlluse~1&blue.exe –TargetIp & star.exe –OutConfig a –TargetPort 445 –Protocol SMB –Architecture x64 –Function RunDLL –DllPayload down64.dll –TargetIp
Something looks similar here… 🙂
5ss5c ransomware – how it operates
Back to the actual ransomware. It will create the following mutexes:
- SSSS_Scan; and,
|Figure 4 – Exclusion list|
For example, the following folders belonging to Qihoo 360 (an internet security company based in China also offering antivirus) were already excluded in Satan and DBGer ransomware:
While these are new in 5ss5c ransomware:
As in previous iterations, 5ss5c ransomware will stop database-related services and processes.
It will however only encrypt files with the following extensions:
7z, bak, cer, csv, db, dbf, dmp, docx, eps, ldf, mdb, mdf, myd, myi, ora, pdf, pem, pfx, ppt, pptx, psd, rar, rtf, sql, tar, txt, vdi, vmdk, vmx, xls, xlsx, zip
This extension list is not like before, and includes mostly documents, archives, database files and VMware-related extensions such as vmdk.
The ransomware will then create the following URI structure to communicate with the C2 server (61.186.243[.]2):
It will also create a ransomware note on the C: drive as: _如何解密我的文件_.txt which translates to _How to decrypt my file_.txt. Example content is as follows:
|Figure 5 – ransom note|
The content reads:
如果你想找回加密文件,发送 (1) 个比特币到我的钱包
Some files have been encrypted
If you want to retrieve the encrypted file, send (1) Bitcoins to my wallet
If payment is not completed within 48 hours from the start of encryption, the amount of decryption will double.
If you have other questions, you can contact me by email
Your decryption credentials are:
Interestingly, the ransomware note does not contain a Bitcoin address. Additionally, the note only contains instructions in Chinese, not Korean nor English like previous iterations. Is 5ss5c ransomware more targeted, or just actively being tested by the group/developers behind it?
Encrypted files will have the actor’s email address prepended and a unique token with the ransomware’s name will be appended, for example;
test.txt becomes [email@example.com]test.txt.Y54GUHKIG1T2ZLN76II9F3BBQV7MK4UOGSQUND7U.5ss5c.
- Enable UAC;
- Enable Windows Update, and install updates (especially verify if MS17-010 is installed);
- Install an antivirus, and keep it up-to-date and running;
- Install a firewall, or enable the Windows Firewall;
- Restrict, where possible, access to shares (ACLs);
- Create backups! (and test them)
Satan is dead, long live 5ss5c! It just doesn’t sound as good, does it?
Whoever’s behind the development of Satan, DBGer, Lucky and likely Iron ransomware, is back in business with the 5ss5c ransomware, and it appears to be in active development – and is trying to increase (or perhaps focus?) its targeting and spread of the ransomware.
It is recommended organisations detect and/or search for the indicators of compromise (IOCs) below, and have proper prevention controls in place. MITRE ATT&CK IDs can also be found below.
Indicators of Compromise:
|File C:Program FilesCommon FilesSystemScanlog|
|File C:Program FilesCommon FilesSystemcpt.exe|
|File C:Program FilesCommon FilesSystemtmp|
|Registry key SOFTWAREMicrosoftWindowsCurrentVersionRun5ss5cStart|
|Command C:Windowssystem32cmd.exe /c cd /D C:ProgramData&blue.exe –TargetIp|
|Command star.exe –OutConfig a –TargetPort 445 –Protocol SMB –Architecture x64 –Function RunDLL –DllPayload C:ProgramDatadown64.dll –TargetIp|
These indicators are also available on AlienVault OTX:
Satan ransomware rebrands as 5ss5c ransomware
MITRE ATT&CK techniques