GandCrab Ransomware Windows PE
SonicWall Capture Labs Threat Research Team recently found a new sample and activity in May for GandCrab Ransomware. GandCrab is well known across 2018 and 2019 as ransomware-as-a-service (RaaS). The RaaS model allows affiliates to attack victims with minimal effort. GandCrab encrypts critical data files, demands ransom payments and escalates if the victim delays payment. Once the victim provides payment, their data will be decrypted with a secret key that is provided once the payment is completed. The kill chain for this sample is a 32 bit PE file with resource files that are encrypted. The resource will be decrypted and placed on your system then executed through ShellExecuteExW. Once executed the infection will spread across well known files and network shares encrypting everything it can get access too.
Sample Static Information:
SHA-256 Hash: bbbb28aaa1050337356d9931a03533a522cd911e17aac2ac5003915419b126d7
This sample has aPLib Compression and an Entropy of 7.31:
Unpacking The Sample:
The sample is not packed, only compressed with aPLIb, so this makes the sample easier to research inside Ida Pro:
We can also see that the malware has about 787 functions available to research.
HTTP Network Objects:
The domain the sample connects to is “carder.bit” and another ip associated is “22.214.171.124”.
The ransom id is also sent through the network.
The sample contains a list of hardcoded process names which are closed and terminated before the encryption starts. This solves a handle issue that might arise when trying to encrypt the following list of processes.
List of User-Mode Anti-Virus Detections:
Compares running processes with hardcoded Anti-Virus executable process names.
List of Kernel-Mode Anti-Virus Detections:
This sample has pretty complex encryption and decryption techniques mostly for Anti-Analysis. This is what was found after a few rounds of decryption.
The sample was tested and debugged on (x86) – 32 Bit, Windows 7 Professional.
GandCrab ransomware is a well-known malware that is distributed with multiple exploit kits, email spam and the Dark Web. GandCrab is Russian in origin, and targets many different countries in 2019 such as the US, Australia, Sweden and Canada. GandCrab currently has many active affiliates over the web and thousands of samples scattered across the wild in 2019. It’s estimated that ransom payouts in 2018 reached millions of dollars.
Hit Graph & Statistics:
SonicWall, (GAV) Gateway Anti-Virus, provides protection against this threat:
- GAV: GandCrab.C_2