BLACK FRIDAY: 2-for-1 offer NOVEMBER 20 - 26 See details
22
Global rank
36
Month rank
30
Week rank
1163
IOCs

GandCrab is probably one of the most famous Ransomware. A Ransomware is a malware that asks the victim to pay money in order to restore access to encrypted files. If the user does not cooperate the files are forever lost.

Ransomware
Type
ex-USSR territory
Origin
26 January, 2018
First seen
2 December, 2023
Last seen

How to analyze GandCrab with ANY.RUN

Type
ex-USSR territory
Origin
26 January, 2018
First seen
2 December, 2023
Last seen

IOCs

Hashes
c0fcdd808306bc80b509d7f8a191920d16528df31181d8be8be61e1889e10a8b
c2c77630e84eb96f7b911eb6b2acea0ab2eb56060246e57d4a9bca13a32e8676
1147b10fed10b4f0298271a5389fc8c044337700849c266640100da211284aba
620f3a01468605e970bf362800d50f07e5b6a53f325f600c262badeacfb998cf
7ebc63a30003ebc6e4fcec1a561ea7a95ff6e2d0b2e5d4a27fc374ecc8babcb0
3292a9d29466fb49b60485a34b5b6dc855eb0ff89cd8ab05104753644582df0a
6c1ed5eb1267d95d8a0dc8e1975923ebefd809c2027427b4ead867fb72703f82
a6ecfade2558a662da276a3faa1ed5d411fe086bd3c7ffd59d582ef0a1c1d0f4
9f968af9355d4e94ef40ae18f5d34ba60ca4af2fe830ff4b2adb8611e9c2ff1d
50c41cf9b7751662d52675c51a4fce3f1c08c107a73325c5ad9ad8625bb00a81
415a383a6549ed33982c6a8e9ec6e3b766125fb47177080afbd1e4cc4090d280
686cc963f386996e67a673348f5f1e300445d6e51987765b2f8fc4b11ba08426
eb966f048f5dd57ca12f8f575e99a0e179b534210fe4df10c1a74a254adfe6d2
b2a44ed3e433939682c7ed2a9ea8b30a38660d66910c9d3e572d116b37f3a6d2
e9312ac6b24d0a13e4c70a1d6bd99a08f7b4ed1b3af3798069b39e595428e645
c30efc6db7417e90d749b3d531d750d385419b01c7c81d6cfc355267157d9831
9e1dbac9efc44fb230cad8c9f8a4005ed5846b0c3785e50fbf28af2421991b1a
371fcc5358373160da71c784a46150f68bbbaec8f360b1c82636be4b75af59d4
ee13b58ead24a446f736bd149908c9ff738c558544206bc0b7c1236e4723a923
64a034db5cc8a46638528721834ef58a58347d61d4059d58644ef6ec8e47549e
URLs
http://www.haargenau.biz/uploads/tmp/esamfu.bmp
http://www.haargenau.biz/
http://www.macartegrise.eu/news/images/kemoheda.png
http://www.macartegrise.eu/
http://www.macartegrise.eu/news/images/thso.bmp
http://www.wash-wear.com/data/pics/thzuhedameme.gif
http://www.wash-wear.com/
http://www.macartegrise.eu/wp-content/assets/kada.bmp
http://asl-company.ru/includes/image/semohe.jpg
http://asl-company.ru/
http://www.macartegrise.eu/wp-content/graphic/imzues.png
http://www.kakaocorp.link/includes/graphic/thseessomode.jpg
http://www.kakaocorp.link/
http://www.kakaocorp.link/data/imgs/daimso.jpg
http://www.kakaocorp.link/uploads/tmp/imamfuso.jpg
http://www.macartegrise.eu/wp-content/tmp/moth.png
http://www.kakaocorp.link/data/tmp/immethim.png
http://perovaphoto.ru/data/image/esmeke.jpg
http://www.poketeg.com/news/assets/dezumo.gif
http://www.mimid.cz/news/pics/kekasethmo.jpg
Last Seen at

Recent blog posts

3 Cybersecurity Events ANY.RUN Attended in No...
watchers 142
comments 0
5 malware threats we discovered in the wild i...
watchers 345
comments 0
RisePro Malware Analysis: Exploring C2 Commun...
watchers 2314
comments 0

What is GandCrab ransomware?

GandCrab is a ransomware-type malware, which means that it encrypts files on infected machines and demands a ransom in cryptocurrency to restore the lost data. What’s more, this particular strain is distributed as a Ransomware-As-A-Service, allowing anybody to use this program by purchasing access to a control dashboard.

A unique business model and constant updates of the malware, in turn, helped GandCrab to become one of the most widely spread ransomware of 2018.

General Description of GandCrab

Since its discovery on January 26, 2018, at least 5 versions of GandCrab were created. The authors of the program are extremely active and respond to created countermeasures almost instantly, making GandCrab an elusive malware that continues to terrorize private and corporate victims today.

The last identified version of the malware is 5.1 and it targets users from all over the world with one exception – having originated in an ex-USSR country GandCrab is known to ignore users from X-USSR territories, identifying them by the keyboard or UI language settings. Only Windows operating systems are affected by ransomware.

It should be noted, that the virus is assigned a different name by various antivirus software:

  • Ransom: Win32/GandCrab
  • Trojan.Ransom.GandCrab
  • Win32/Filecoder.GandCrab
  • Ransom.GandCrab
  • Trojan-Ransom.Win32.GandCrypt

Usually infecting users through mail spam or exploit kits, the ransomware redirects victims to a TOR website after the files on a victim’s PC are encrypted. For the newer versions of the malware, the only way of restoring the data is through paying the ransom, the amount of which usually fluctuates between 1000 and 3000 dollars. However, some victims, have reported that they were asked to pay as much as 700,000 USD.

Having a RaaS ( Ransomware-as-a-Service ) business model, GandCrab is distributed by the original creators to “clients”, who then deliver the malware to end victims, asking for a custom ransom amount through one of the unique features of the virus – customizable ransom notes. A percentage of the “revenue” is then shared with the malware authors, once a ransom is secured.

GandCrab malware analysis

ANY.RUN provides the ability to watch the GandCrab program in action in interactive virtual machine simulation. Notably, ANY.RUN simulation can be used to perform the analysis of the stages of the virus life cycle:

  • Infection. A victim downloads and opens infected Microsoft Office file which contains a script programmed to download and start the execution of the virus;
  • Execution and information gathering. After the script has started the execution process, GandCrab collects information about the user. At this stage, the execution of the virus is stopped if a Russian keyboard layout or user interface is detected;
  • The malware checks for the presence of antivirus drivers and stops all processes that involve files that it wants to encrypt;
  • The ransomware decrypts the ransom record held in the binary;
  • Next, a key pair is generated;
  • The virus enumerates file and decryptors;
  • GandCrab proceeds to encrypt the files;
  • The malware establishes communication with the server;
  • After that, the malware will try to delete all shadow copies;
  • Finally, a ransom note is displayed to the user.

wallpaper after infection by gandcrab ransomware

Figure 1: Some versions of GandCrab are known to change the desktop wallpaper. This function is omitted in version 5.0.

ransomnote displayed by gandcrab v5.1

Figure 2: A ransomware note displayed by GandCrab v5.1

The following contamination processes are launched by the ransomware:

  • Starts CMD.EXE for commands execution
  • Executes PowerShell scripts
  • Downloads executable files from the Internet
  • Connects to CnC server
  • Makes registry changes
  • Runs wmic.exe
  • Executes vssvc.exe
  • Deletes shadow copies
  • Runs NOTEPAD.EXE

The whole contamination process can be seen in a video, displaying the ANY.RUN simulation.

gandcrab execution process graph

Figure 3: Illustrates the processes launched by GandCrab during its life cycle.

To build itself into the system, GandCrab starts with decrypting an extension name record that is held in the binary. By going through logical drives from “a” to “z” the malware separates all drives that are equal to 0x2 and not equal to 0x5, creating and separating thread to enumerate and encrypt all data that is prepared for encryption. After the encryption is complete, the malware uses wmic to erase all shadow copies. As a result, all data remains affected by the program even after a reboot.

The ransomware leaves behind artifacts that can help to recognize the version. Those exist in the form of extensions of encrypted files.

  • Version 1 gives the .gdcb extension
  • Version 2 and 3 give the .crab extension
  • Version 4 gives the .krab extension
  • Version 5 gives a randomized 5 or more letter extension

How to avoid infection by GandCrab?

According to the analysis, creators of GandGrab patch all exploits in the malware code fairly quickly, which makes the development of countermeasures tricky. Upon contamination with on of the latest versions, the only way to restore the lost data is to pay the ransom. Thus, the best way to stay safe is to prevent contamination.

  • By keeping digital copies of important files in multiple places
  • By making sure that the antivirus software is reliable and updated
  • Avoiding digital downloads on suspicious or unknown websites
  • Avoiding opening the attached files in emails, especially those coming from unknown senders.
  • And not paying the ransom if infected.

That said, effective countermeasures do exist for older versions of the ransomware like Troldesh or Nemty, including free decrypters and Killswitches. Most notably, a Killswitch for GandCrab v4.1.2 was developed by a cyber threat analysis and response company Ahnlab. The defensive application exploits the mechanics of GandCrab ransomware by creating a file with the .lock extension, which simulates the files that GandCrab itself generates and uses to check whether the victim's computer is included in the record of previously affected machines to avoid double decryption.

The execution of the ransomware stops upon discovery of .lock file if it is placed in %Application Data% for Windows versions before Windows 7 and in %ProgramData% directory for newer OS versions. Even in cases when the malware has already activated, the killswitch will prevent some of the damage.

Interestingly, in response to the killswitch, the GandCrab authors released an exploit, targeting the Ahnlab antivirus software. The exploit was introduced in version v4.2.1 and v4.3 of the malware but did not cause sufficient harm to the antivirus users.

For versions 1, 4 and up through 5.1 there are free decryption tool from Bitdefender.

Distribution of GandCrab

Based on the analysis, ransomware is known to utilize multiple attack vectors, however, compromised list and spam email campaigns are the most commonly used delivery channels. Being delivered to users in spam emails, GandCrab tricks users into downloading a ZIP archive that contains a script file that triggers the download and execution.

GandCrab execution process

An illustration of an execution process can be found below.

gandcrab execution process tree

Figure 4. Analysis of the GandCrab execution process in ANY.RUN

The following behavioural activities are shown in ANY.RUN’s report.

text report of the gandcrab ransomware analysis

Figure 5: A text report created in ANY.RUN

During the execution the malware creates several artifacts that can be viewed in detail in the ANY.RUN simulation.

With file encryption being the main goal of the payload, the malware launches a command line with pre-specified parameters after opening a Microsoft Word file. Startup powershell is then sent as command line parameters, followed by downloading and launching the executable file from the Internet.

How to detect Gandcrab using ANY.RUN?

You can perform the analysis of files using ANY.RUN's "Static Discovering". Open either "Files" tab in the lower part of the task's window or click on the process and then on the button "More Info" in the appeared window. After that, all you need to do is just click on the file.

gandcrab ransom note

Figure 6: Gandcrab ransom note

Conclusion

Thanks a unique business model which involves selling the program as a service and defining characteristics like customizable ransom notes, GandCrab’s popularity quickly escalated in 2018, making the virus the most widely spread ransomware of the year.

Unfortunately, the creators proved to be very active and continued to respond quickly to all attempts to create effective countermeasures. While adhering to common practices of staying safe on the internet decreases the probability of getting attacked greatly, running interactive sandbox simulations in a service such as ANY.RUN is the best way to ensure personal or corporate safety.

P.S.

On the 1st June 2019 creators of the GandCrab ransomware made a post in which they stating that they have generated more than $2 billion in ransom payments, with average weekly payments of $2.5 million dollars. They also said that they have personally earned $150 million, which they have cashed out and invested in legal business entities. In the same post, they announced about ending of distributing the program within 20 days and that keys will be deleted.

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
Amadey screenshot
Amadey
amadey
Amadey is a formidable Windows infostealer threat, characterized by its persistence mechanisms, modular design, and ability to execute various malicious tasks.
Read More
Arkei screenshot
Arkei
arkei stealer
Arkei is a stealer type malware capable of collecting passwords, autosaved forms, cryptocurrency wallet credentials, and files.
Read More
AsyncRAT screenshot
AsyncRAT
asyncrat
AsyncRAT is a RAT that can monitor and remotely control infected systems. This malware was introduced on Github as a legitimate open-source remote administration software, but hackers use it for its many powerful malicious functions.
Read More
WarZone screenshot
WarZone
warzone avemaria stealer trojan rat
WarZone RAT is a remote access trojan, which is written in C++ and offered as a malware-as-a-service. It packs a wide range of capabilities, from stealing victims’ files and passwords to capturing desktop activities. WarZone RAT is primarily distributed via phishing emails and receives regular updates from its C2.
Read More

Our website uses cookies. By visiting the pages of the site, you agree to our Privacy Policy