Sodinokibi

Sodinokibi, also called Revil is a dangerous ransomware-type malware. Among other tools, it uses advanced encryption techniques and can operate without connection to control servers. Sodinokibi is among the most complex Ransomware in the world.

Type
Ransomware
Origin
ex-USSR
First seen
1 April, 2019
Last seen
12 July, 2020
Also known as
REvil
Sodin
Global rank
24
Week rank
12
Month rank
21
IOCs
344

What is Sodinokibi?

Sodinokibi, sometimes also called REvil, is a ransomware-type malware - it encrypts files on infected machines and demands a ransom from the victims to restore the files. Sodinokibi is distributed with a Ransomware-as-a-Service business model, allowing anybody who is able to pay can become an operator of the virus.

Sodinokibi is very sophisticated ransomware, seemingly developed by a group with vast experience in the field. It bears a lot of similarities to another malware called GandCrab - so much so, in fact, that it is believed to be created by the same group of cybercriminals. However, while GandCrab already was complicated and dangerous ransomware, Sodinokibi can be considered its much-upgraded version.

Sodinokibi ransomware is capable of encrypting files with curve25519/Salsa20 and encrypting keys with curve25519/AES-256-CTR. The malware uses 2 public keys to encrypt the private key of the user. In addition, this virus utilizes command and control server obfuscation and can operate using the asymmetric key scheduling algorithm, which allows the malware to function without connection to the C2.

General description of Sodinokibi

Sodinokibi first appeared on the radar of cybersecurity researchers in April of 2019, when the malware was featured in a campaign that exploited the Oracle WebLogic Server vulnerability.

The campaign began shortly before another similar malware called GandCrab was officially shut down for good. Some researchers believe that Sodinokibi is a “spiritual successor” of GandCrab, while others support the theory that it is, in fact, the next generation of the same virus. Some evidence suggests the theory to be correct.

Among such evidence are the vast similarities in the code of both malware and the fact that in the early stages of Sodinokibi life cycle, criminals used to deploy GandCrab after running Sodinokibi on all infected machines as a precaution, likely because Sodinokibi wasn’t yet thoroughly tested in operation.

Another piece of evidence in favor of this theory is an attack that took place in February 2019, when GandCrab was used to infect victims by compromising Managed Service Providers. Sometime after, the same attack took place, but instead of GandCrab, it featured Sodinokibi ransomware.

In addition, the fact that Sodinokibi malware became popular as GandCrab started to cease operations can not be ignored and it would be strange to think about it as a coincidence. In addition to that both malware use very similar distribution methods - something we will explore later in the article.

Finally, it is thought that GandCrab authors started “feeling the heat” and while worried that their operation can be uncovered decided to go under the radar by terminating sales of the publicly available GandCrab in favor of a more advanced malware which could be sold to private parties.

Of course, neither of these points is solid evidence and we can only imagine that both viruses are the result of the work of the same people.

Let’s talk about the behavior of Sodinokibi ransomware.

At the beginning of the execution process, the malware generates a mutex that has a hardcoded name. Then, it decrypts a configuration which is embedded. At this stage, Sodinokibi tries to get system privileges by exploiting CVE-2018-8453. In some cases, this step can be omitted in configuration or may not be successful. Then, it tries to obtain privileges by running as an admin.

Following the privilege escalation stage, the ransomware collects basic system and user data. If it finds that the UI or keyboard layout is set to one of the pre-programmed languages, the execution will be terminated. Many of these languages originate from post-USSR territories which may suggest that the malware authors also come from ex-USSR lands.

In a case when the target PC lacks the specified UX or keyboard layout languages, the virus terminates processes by PRC value and proceeds to erase shadow copies. At this point, the data encryption process begins. The ransomware encrypts all user files unless some exceptions are found in the configuration. This is where an attacker can customize their campaign. An extension is then added to all encrypted documents and a README text is placed in directories. The wallpaper is changed to the ransom demand message.

The contents of the ransom note and the README file can be customized by the attackers in the config file which, once again, provides the malware with flexibility which allows it to operate as ransomware-as-a-service since different attackers can demand ransoms of various sums and provide custom instructions to victims.

Sodinokibi malware analysis

ANY.RUN provides the ability to watch the Sodinokibi ransomware in action via an interactive virtual sandbox simulation.

sodiokibi execution process graph Figure 1: illustrates the processes launched by Sodinokibi during its life cycle.

workstation desktop after Sodinokibi infection Figure 2: Wallpapers with ransom message set by Sodinokibi

Sodinokibi execution process

Sodinokibi won't run malicious activity on systems where UI and keyboard languages are set to a specific value, such as Russian, Ukrainian, and 18 others. Although Sodinokibi is a "qualitative" type of malware, its execution, and system infection process, in general, is quite straightforward and similar to another ransomware - it decrypts files, erases shadow copies and places ransom notes across the file system. Process tree also doesn't look very exciting because all main activities are provided by a single executable. For all infected files, the ransomware changes extensions to generated. The added extension is the same as an ID which is unique and made by combining the hash of the value given by CPUID instruction and the volume serial number. It should be noted that Sodinokibi will also try to encrypt files on network shares. After completion of the decryption process, the ransomware sets background wallpaper to a ransom message.

Interesting that authors of Sodinokibi created a high-quality website available at the domain decryptor.top, where victims can use a trial decryptor and have the opportunity to decrypt three images for free. Besides the decryption function, this website provides various information such as the countdown (after time runs out, the ransom amount will be set to 5 000 dollars), instructions on how to buy bitcoins and where to send it, as well as information about the decryption process. If decryptor.top is not available, there is a possibility for victims to visit its .onion clone through the Tor web browser.

How does Sodinokibi spread?

To infiltrate the machines of its victims, Sodinokibi takes advantage of quite a number of infection vectors, most of which are very similar to its predecessor - GandCrab.

As such, the RAAS is known to utilize the CVE-2019-2725 vulnerability and use the RIG exploit kit. Additionally, Sodinokibi also spreads via compromised managed service providers. And, like an icing on the cake, on top of the attack vectors mentioned above, this ransomware is often distributed in malicious spam campaigns.

Sodinokibi communication with C&C

Interestingly, while many ransomware needs to connect to C2 for exchanging encryption keys, Sodinokibi uses something called asymmetric key scheduling algorithm.

It enables the RAAS to operate without any network connection and not giving the user any chance to get their hands on data that could help with file decryption. However, attackers can optionally establish a connection with the control server to retrieve general system data from infected machines by tweaking the config file.

System and user data then will be transmitted to a broad list of web domains many of which look completely real and legal - possibly compromised WordPress websites, many of which can be included to hide the real C&C web address. In return, Sodinokibi can receive and read the response from the server, but it is not being saved or used in any way during the operation.

How to prevent Sodinokibi attacks?

While the use of vulnerabilities allows this ransomware to infected machines without active user actions, basic rules of online hygiene can still greatly decrease the probability of “catching” this virus.

In particular, not downloading attachments in suspicious emails or emails that arrived from unknown senders and keeping the macros disabled in Microsoft Office completely guarantees that one won’t be infected with Sodinokibi via a malicious spam email campaign.

How to get more information from Sodinokibi analysis?

Since crooks behind Sodinokibi offer decryption of three images for free you can use the interactivity of ANY.RUN to take additional steps in your analysis. Open the website specified in a ransom note in the browser and follow all steps to decrypt images to get a bigger picture of a ransomware infection process.

Sodinokibi payment website Figure 3: Sodinokibi payment website

Conclusion

Since its introduction in 2019, thousands of computers were already infected with Sodinokibi and this malware is continuing to be an ongoing danger.

Borrowing much of the functionality from already quite powerful GandCrab ransomware, Sodinokibi improves on it even further to become a real powerhouse of ransomware. Unfortunately, evidence suggests that this malware is developed by experienced cybercriminals who know how to build and distribute a virus and its accessibility thanks to malware as a service business model makes it a real threat to businesses and individuals all around the world.

Thankfully, malware analysis services like ANY.RUN allow cybersecurity researchers to study such threats and prepare their defenses accordingly.

IOCs

IP addresses

No IP adresses found

Hashes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No hashes found

HAVE A LOOK AT

Adwind screenshot
Adwind
adwind trojan
Adwind RAT, sometimes also called Unrecom, Sockrat, Frutas, jRat and JSocket is a Malware As A Service Remote Access Trojan that attackers can use to collect information from infected machines. It was one of the most popular RATs in the market in 2015.
Read More
Agent Tesla screenshot
Agent Tesla
agenttesla trojan rat stealer
Agent Tesla is spyware that collects information about the actions of its victims by recording keystrokes and user interactions. It is falsely marketed as a legitimate software on the dedicated website where this malware is sold.
Read More
Ave Maria screenshot
Ave Maria
avemaria stealer trojan rat
Ave Maria malware is a Remote Access Trojan that is also called WARZONE RAT. Hackers use it to control PCs of their victims remotely and steal information from infected PCs. For example, they can remotely activate the camera to take pictures of a victim and send them to a control server
Read More
Azorult screenshot
Azorult
azorult trojan rat
AZORult can steal banking information including passwords and credit card details as well as cryptocurrency. This constantly updated information stealer malware should not be taken lightly, as it continues to be an active threat.
Read More
Crimson RAT screenshot
Crimson RAT
crimson rat trojan
Crimson is a Remote Access Trojan — a malware that is used to take remote control of infected systems and steal data. This particular RAT is known to be used by a Pakistani founded cybergang that targets Indian military objects to steal sensitive information.
Read More
Danabot screenshot
Danabot
danabot trojan stealer
Danabot is an advanced banking Trojan malware that was designed to steal financial information from victims. Out of the Trojans in the wild this is one of the most advanced thanks to the modular design and a complex delivery method.
Read More