The WannaCry ransomware outbreak this week garnered widespread attention for its sheer global scope and audacity but another likely even bigger attack leveraging the same stolen NSA exploits has been going on unnoticed potentially since the last week of April.
Security vendor Proofpoint Tuesday said it had identified a massive campaign to install Adylkuzz, a crypto-currency mining tool, on hundreds of thousands of systems worldwide.
As with WannaCry, the threat actors behind the Adylkuzz campaign are using the NSA's leaked EternalBlue exploit to target legacy Windows systems running a vulnerable version of the Microsoft Server Message Block (SMB) protocol.
"Upon successful exploitation via EternalBlue, machines are infected with DoublePulsar," which then downloads and runs Adylkuzz from another host system, Proofpoint said in an alert.
Once installed, Adylkuzz blocks all SMB communications on the infected system, looks for and stops any previous instances of itself on the same computer and then downloads a cryptominer and mining instructions.
Adylkuzz is not ransomware. Rather it is a so-called "miner" for Monero, a cryptocurrency that is similar to, but not as widely used as, bitcoin.
Computers infected with Adylkuzz become part of a broad distributed banking network for Monero, says Kevin Epstein vice president of threat operations at Proofpoint. "It is used as part of that network, largely for maintaining accounting or bookkeeping transactions within that network, as well [as for] money supply," he says.
In compensation for the use of the computer, the network typically pays a small fee equivalent to around $205 at current exchange rates to the miner, which in this case would really be the attacker that installed Adylkuzz.
Individual laptops might only generate a few dollars on a weekly basis but the collective payout from all of the infected systems easily tops five-figures daily, Epstein says.
Because no encryption or ransom demands are involved, victims of Adylkuzz do not realize they have been compromised. Degraded PC and server performance and the loss of access to shared Windows resources are often the only indications of a compromise, Epstein says.
Several large organizations that eported experience network performance issues this week were likely victims of the AdylKuzz campaign considering the timing of the incidents and the fact that none of them reported receiving ransomware notices.
"The malware is deliberately stealthy," Epstein says. "Users will only notice their Windows machine is running slowly and that they don't have access to shared Windows resources."
Proofpoint security researchers discovered the Adylkuzz attack while investigating the WannaCry campaign. It found that the attacks are being launched from multiple virtual private servers, which are also being used to massively scan the Internet for other systems to exploit.
Available data suggests that the operators of the Adylkuzz campaign are using multiple command and control servers to manage infected systems and to download cryptominer binaries and instructions for mining, Proofpoint said.
"WannaCry is a very noisy threat. You need to know it is there in order to get you to pay the ransom," says Brian Vecci, technical evangelist at Varonis. "This is different and more dangerous. It does not want you to know it's there," he says.
What attacks like WannaCry and AdylKyzz highlight are just how bad the threat situation has become with the release of the NSA's weaponized exploits. In this case, adversaries used the NSA's EternalBlue and Double Pulsar tools to distribute ransomware and a crypto mining too. But they could use it just as easily to deliver other potentially more lethal payloads, he says.
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