Bad Rabbit Ransomware Spread Via Fake Flash Player Updates
A new ransomware threat has been detected – named Bad Rabbit ransomware – that has crippled businesses in Russia, Ukraine, and Europe. Some Bad Rabbit ransomware attacks have occurred in the United States. Healthcare organizations should take steps to block the threat.
There are similarities between Bad Rabbit ransomware and NotPetya, which was used in global attacks in June. Some security researchers believe the new threat is a NotPetya variant, others have suggested it is more closely related to a ransomware variant called HDDCryptor. HDDCryptor was used in the ransomware attack on the San Francisco Muni in November 2016.
Regardless of the source of the code, it spells bad news for any organization that has an endpoint infected. Bad Rabbit ransomware encrypts files using a combination of AES and RSA-2048, rendering files inaccessible. As with NotPetya, changes are made to the Master Boot Record (MBR) further hampering recovery. This new ransomware threat is also capable of spreading rapidly inside a network.
The recent wave of attacks started in Russia and Ukraine on October 24, with attacks also reported in Bulgaria, Germany, Turkey, and Japan. ESET and Kaspersky Lab have analyzed the new ransomware variant and have established that it is being spread by drive-by downloads, with the ransomware masquerading as a Flash Player update.
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The actors behind this latest campaign appear to have compromised the websites of several news and media agencies, which are being used to display warnings about an urgent Flash Player update. No exploits are believed to be involved. User interaction is required to download and run the ransomware.
Users that respond to the Flash Player warning download a file named “install_flash_player.exe.” Running that executable will launch the ransomware. After files have been encrypted and the MBR has been altered, the ransomware reboots the infected device and the ransom note is displayed.
The ransom amount is 0.5 Bitcoin ($280) per infected device. Victims must pay the ransom within 40 hours or the ransom will increase. Whether payment of the ransom allows files to be recovered is uncertain.
The ransomware is also spreading within networks via SMB. Initially thought that no NSA exploits were used, instead, the ransomware scans for network shares and uses Mimikatz to harvest credentials. The ransomware also cycles through a list of commonly used usernames and passwords. If the correct credentials are found, a file called infpub.dat is dropped and executed using rundll.exe. This process allows the ransomware to spread quickly within a network. However, researchers at Cisco Talos believe that the ETERNALROMANCE NSA exploit has been incorporated. ETERNALROMANCE leverages the CVE-2017-0145 vulnerability.
“This is a different implementation of the EternalRomance exploit,” said Cisco Talos’ Martin Lee, “It’s different code from what we saw used in NotPetya, but exploiting the same vulnerability in a slightly different implementation.”
There have been at least 200 infections as of October 25, including the Kiev Metro, Odessa International Airport in Ukraine, the Ministry of Infrastructure of Ukraine, and the Russian Interfax and Fontanka news agencies.
Indicators of compromise have been released by Kaspersky Lab and ESET.
It is possible to vaccinate devices to prevent Bad Rabbit ransomware attacks. Kaspersky Lab suggests “restricting execution of files with the paths c:\windows\infpub.dat and C:\Windows\cscc.dat.” Alternatively, create those two files in the C:\\Windows\ directory and remove all permissions on those files for all users.