As the dust settles from Tuesday's Bad Rabbit ransomware outbreak, it's already clear that it is far less severe than the WannaCrypt and NotPetya infections from earlier this year.

Bad Rabbit claimed notable victims including the media agency Interfax and was largely contained in Russia and Ukraine, as previously reported.

According to ESET, 65 per cent of the victims are in Russia, 12.2 per cent in Ukraine. The nasty also hit some other Eastern European countries as well as Turkey and Japan.

Bad Rabbit spread from a network of compromised websites set up by the hackers in preparation for the attack. The dropper, which posed as a Flash Player installer, was downloaded by users when they visited infected websites through a drive-by download (a common hacker tactic). Carrier websites included argumentiru[.]com, which covers current affairs, news and celebrity gossip in Russia and its neighbours, among several others.

Bad Rabbit also attempted to spread to other machines on the same network using worm-like functionality.

Like NotPetya, Bad Rabbit made use of a custom version of the Mimikatz password recovery tool as well as SMB network shares to spread across machines on the same network.

Security experts found that Bad Rabbit did not use EternalBlue – the stolen and leaked NSA-created exploit previously abused by both NotPetya and WannaCry – to spread. Instead it relies on local password dumps, as well as a list of common passwords, in attempts to hop from an infected machine to other Windows PCs.

Once executed, the malicious code acted like a traditional ransomware, encrypting files before demanding a ransom to decrypt them – a relatively modest 0.05 BTC (around $280).

Infection attempts ceased and attacker infrastructure – both 1dnscontrol[.]com, the dropper delivery site, and sites containing the rogue code – were taken offline around six hours after the ransomware began spreading, according to a count by researchers at Cisco Talos.

Since Russia was the origin of the attack, by the time the US had woken up it had already been blocked by signature-based antivirus and identified by products that relied on generic or behaviour-based malware detection.

CrowdStrike's analysis found that Bad Rabbit and NotPetya DLL (Dynamic Link Library) share 67 per cent of the same code, prompting speculation that the same group might be behind both attacks. This attribution is sketchy, at best. Bad Rabbit is similar to NotPetya in that it is also based on the earlier Petya ransomware. Major portions of the code appear to have been rewritten.

Recovery of infected machines might be difficult but not impossible. Some experts reason that the intent may have been disruption rather than the profit-making cybercrime associated with ransomware strains such as Locky.

"Bad Rabbit appears to be a disruption campaign designed to look like a ransomware campaign, similar to NotPetya and WannaCry," commented Allan Liska, senior solutions architect at threat intel outfit Recorded Future. ®

Bootnote

The hackers behind the ransomware seem to be fans of Game of Thrones as the source code contains references to dragons from the popular TV series (Drogon, Rhaegal and Viserion). The as-yet unidentified crooks also allude to a human character, "GrayWorm", as the product name for the .exe file.