The massive campaign that spread the WannaCry (aka WannaCryptor) ransomware wasn’t the only recent large-scale infection misusing the EternalBlue and DoublePulsar exploits, leaked by Shadow Brokers. The same mechanism was misused by black-hats as early as the end of April, when they opted for the off-the-shelf Monero cryptocurrency mining software, instead of the encrypting payload.
This campaign detected as Win32/CoinMiner.AFR and Win32/CoinMiner.AFU started only a few days after the NSA tools leaked online. ESET had network detections for the vulnerability deployed on April 25th – three days before the first attack attempts by these miners for Monero cryptocurrency.
The biggest uptick was recorded only hours before the mining ransomware’s global outbreak, on May 10th. On that day, mining malware detections increased from hundreds of detections per day to thousands. We have seen such attempts in as many as 118 countries, with Russia, Taiwan and Ukraine topping the list.
However, the mining software consumed system resources so intensely that in some cases it rendered the infected machines unresponsive.
Interestingly the CoinMiner attacks also blocked the 445 port used by the EternalBlue exploit to get into the machine, essentially closing the door to any subsequent infection using the same vector – including WannaCry. If the miners hadn’t taken this precaution, the number of WannaCry infections could have been even greater than reported.
So how bad was the WannaCry attack?
According to ESET telemetry, since Friday, the machines of more than 14.000 users who have enabled ESET LiveGrid, has reported as many as 66.000 WannaCry attack attempts on their devices.
These attacks mainly targeted Russian computers, with over 30.000 attacks, followed by Ukraine and Taiwan, where in both cases they were close to the 8.000 mark.
The chaos that ensued after WannaCry’s global outbreak seems to have motivated other black-hats to scale up their efforts too. We have seen a significant increase in the number of malicious emails sent out by the notorious Nemucod operators, spreading another ransomware.
Also, WannaCry fakes have emerged. These try to ride the wave of its fame by using the same GUI and layout. However, the encrypting capability was missing in all seen instances.
What should you do to stay safe?
- Since the EternalBlue exploit uses a vulnerability in Windows that has been already patched by Microsoft, the first thing would be to verify the completion of the update and the patch to your operating system.
- Use a reliable security solution that utilises multiple layers to protect you from similar threats in the future.
- It is best practice to keep backups on a remote hard disk or location that will not be hit in case of a network infection.
- We recommend that users do not pay ransoms – be it a case of the true WannaCry or any other ransomware. There have been no reported cases where pursuing such a step would lead to decryption. On the contrary, there have been multiple stories documenting the opposite – no decryptor or key being sent after the payment was made. Also, there seems to be no way for the attackers to match the payment to the specific victim who sent it to one of the shared BitCoin wallets.