On October 24th we observed notifications of mass attacks with ransomware called Bad Rabbit. It has been targeting organizations and consumers, mostly in Russia but there have also been reports of victims in Ukraine. Here’s what a ransom message looks like for the unlucky victims:
What is bad rabbit?
Bad Rabbit is a previously unknown ransomware family.
How is bad rabbit distributed?
The ransomware dropper was distributed with the help of drive-by attacks. While the target is visiting a legitimate website, a malware dropper is being downloaded from the threat actor’s infrastructure. No exploits were used, so the victim would have to manually execute the malware dropper, which pretends to be an Adobe Flash installer.
We’ve detected a number of compromised websites, all of which were news or media websites.
Whom does it target?
Most of the targets are located in Russia. Similar but fewer attacks have also been seen in other countries – Ukraine, Turkey and Germany. Overall, there are almost 200 targets, according to the KSN statistics.
Since when does Kaspersky Lab detect the threat?
We have been proactively detecting the original vector attack since it began on the morning of October 24. The attack lasted until midday, although we are still detecting ongoing attacks.
How is it different to ExPetr? Or it is the same malware?
Our observations suggest that this been a targeted attack against corporate networks, using methods similar to those used during the ExPetr attack.
According to our telemetry, the ransomware is spread via a drive-by attack.
The ransomware dropper is distributed from hxxp://1dnscontrol[.]com/flash_install.php
Also according to our telemetry data, victims are redirected to this malware web resource from legitimate news websites.
The downloaded file named install_flash_player.exe needs to be manually launched by the victim. To operate correctly, it needs elevated administrative privileges which it attempts to obtain using the standard UAC prompt. If started, it will save the malicious DLL as C:\Windows\infpub.dat and launch it using rundll32.
Pseudocode of the procedure that installs the malicious DLL
infpub.dat appears to be capable of brute-forcing NTLM login credentials to Windows machines that have pseudo-random IP addresses.
The hard-coded list of credentials
infpub.dat will also install the malicious executable dispci.exe into C:\Windows and create a task to launch it.
Pseudocode of the procedure that creates the task which launches the malicious executable
What’s more, infpub.dat acts as a typical file encrypting ransomware: it finds the victim’s data files using an embedded extension list and encrypts them using the criminal’s public RSA-2048 key.
The public key of the criminals and the extension list
The criminal’s public key parameters:
Public-Key: (2048 bit)
Exponent: 65537 (0x10001)
The executable dispci.exe appears to be derived from the code base of the legitimate utility DiskCryptor. It acts as the disk encryption module which also installs the modified bootloader and prevents the normal boot-up process of the infected machine.
An interesting detail that we noticed when analyzing the sample of this threat: it looks like the criminals behind this malware are fans of the famous books & TV show series Game Of Thrones. Some of the strings used throughout the code are the names of different characters from this series.
Dragon names from Game Of Thrones
Character name from Game Of Thrones
Kaspersky Lab experts are working on a detailed analysis of this ransomware to find possible flaws in its cryptographic routines.
Kaspersky Lab corporate customers are also advised to:
- make sure that all protection mechanisms are activated as recommended; and that KSN and System Watcher components (which are enabled by default) are not disabled.
- update the antivirus databases immediately.
The abovementioned measures should be sufficient. However, as additional precautions we advise the following:
- restricting execution of files with the paths c:\windows\infpub.dat and C:\Windows\cscc.dat in Kaspersky Endpoint Security.
- configuring and enabling Default Deny mode in the Application Startup Control component of Kaspersky Endpoint Security to ensure and enforce proactive defense against this and other attacks.
Kaspersky Lab products detect this threat with the following verdicts:
fbbdc39af1139aebba4da004475e8839 – install_flash_player.exe
1d724f95c61f1055f0d02c2154bbccd3 – C:\Windows\infpub.dat
b14d8faf7f0cbcfad051cefe5f39645f – C:\Windows\dispci.exe