Security experts have uncovered a massive cryptojacking campaign that is targeting MikroTik routers, the hackers aim to change the configuration of the devices to inject a Coinhive cryptocurrency mining script in the users’ web traffic.
The campaign was first spotted by the researcher who goes online with the Twitter handle MalwareHunterBR.
— MalwareHunterBR (@MalwareHunterBR) July 30, 2018
According to Catalin Cimpanu from Bleeping Computer, the campaign first started in Brazil, but it is rapidly expanding to other countries targeting MikroTik routers all over the world.
The same campaign was monitored by the experts at Trustwave that confirmed that campaign initially targeted MikroTik routers used by Brazilians.
“On July 31st , just after getting back to the office from my talk at RSA Asia 2018 about how cyber criminals use cryptocurrencies for their malicious activities, I noticed a huge surge of CoinHive in Brazil.” reads the report published by Trustwave.
“After a quick look I saw that this is not your average garden variety website compromise, but that these were all MikroTik network devices.”
The experts noticed that the compromised devices were all using the same CoinHive sitekey, most of them in Brazil, this means that they were targeted by the same attackers.
According to Trustwave the hackers were exploiting a zero-day flaw in the MikroTik routers to inject a copy of the Coinhive library in the traffic passing through the MikroTik router.
“Initial investigation indicates that instead of running a malicious executable on the router itself, which is how the exploit was being used when it was first discovered, the attacker used the device’s functionality in order to inject the CoinHive script into every web page that a user visited.” continues the analysis.
The vulnerability was discovered in April and patched by the vendor in just one day.
Trustwave pointed out that many users that weren’t using the MikroTik routers were affected too because Internet providers and big organizations leverage MikroTik routers compromised by hackers.
The experts noticed that the threat actors once discovered to have been spotted by the experts switched tactics and injected the Coinhive script only in error pages returned by the routers.
After the initial phase, the campaign was targeting devices outside Brazil, and it has been estimated that roughly 170,000 MikroTik routers were compromised to inject the Coinhive script. The campaign can potentially compromise over a million of MikroTik routers exposed on the Internet.
“The attacker wisely thought that instead of infecting small sites with few visitors, or finding sophisticated ways to run malware on end user computers, they would go straight to the source; carrier-grade router devices,” concludes the experts.
“Even if this attack only works on pages that return errors, we’re still talking about potentially millions of daily pages for the attacker.”