The cloud-based infrastructures that enterprise organizations are increasingly using to run their business applications have become a major target for illicit cryptomining operations.
According to new research from AT&T Cybersecurity, cryptomining has become the primary reason for most cloud infrastructure attacks these days. There's no sign the attacks will let up soon, either, despite the drop in values of major cryptocurrencies, the vendor said in a report Wednesday.
Cryptojacking — or attacks where an organization's (or an individual's) computers are surreptitiously used to mine for Monero and other cryptocurrencies — has emerged as a major problem over the last 18 months or so.
Cybercriminals have been extensively planting mining tools such as Coinhive on hacked websites and quietly using the systems of people visiting the sites to mine for cryptocurrencies. They have also been deploying mining software on larger, more powerful enterprise servers and on cloud infrastructure for the same purpose.
"Hijacking servers to mine currency really picked up in 2017, at the height of the cryptocurrency boom when prices were at the highest and the potential rewards were very significant," says Chris Dorman, security researcher at AT&T Cybersecurity. "Even though bitcoin prices have dropped 80% since their peak, the prevalence of server cryptojacking continues."
AT&T Cybersecurity's researchers examined cryptomining attacks against a range of cloud infrastructure targets. Container management platforms are one of them. The security vendor says its researchers have observed attackers using unauthenticated management interfaces and open APIs to compromise container management platforms and use them for cryptomining.
As one example, the researchers pointed to an attack that security vendor RedLock first reported last year, where a threat actor compromised an AWS-hosted Kubernetes server belonging to electric carmaker Tesla and then used it to mine for Monero. AT&T Cybersecurity said it has investigated other similar incidents involving malware served from the same domain that was used in the Tesla attack.
Attackers have also been frequently targeting the control panels of web hosting services, as well. In April 2018, for instance, an adversary took advantage of a previously unknown vulnerability in the open source Vesta hosting control panel (VestaCP) to install a Monero miner on web hosts running the vulnerable software.
Container management systems and control panels are not the only cloud infrastructure targets. API keys are another favorite. AT&T Cybersecurity says many attackers are running automatic scans of the web and of sites such as GitHub for openly accessible API keys, which they then use to compromise the associated accounts.
The trend requires due diligence on multiple fronts. Almost all server-side exploits in the cloud, for instance, stem from exploits in software such as Apache Struts and Drupal, Dorman says. "Typically, we see the attackers start scanning the Internet for machines to compromise within two or three days of an exploit becoming available," he notes. So, keeping machines patched fairly quickly is key.
Similarly, ensuring complex password use and enforcing account lockouts is critical to preventing attackers from simply brute-forcing passwords to cloud servers, he says.
In terms of cloud accounts being compromised — when an attacker steals the root AWS key, for instance — there are free tools available to check all public source code and to verify if any credentials have been accidentally published, Dorman notes.
Malicious Docker images are yet another avenue of attack. Cybercriminals are hiding cryptominers in prebuilt Docker images and uploading them to Docker Hub, AT&T Cybersecurity said. Prebuilt images are popular among administrators because they can help reduce the time required to set up and configure a container app. However, if the image is malicious, organizations can end up running a cryptominer as well. So far, though, only a relatively small number of organizations have reported downloading and running malicious containers, AT&T Cybersecurity said.
For enterprises, cryptomining attacks in the cloud are a little trickier to address than attacks on on-premises systems. Deploying network detection tools, for instance, typically tends to be more difficult in the cloud. "You may have to rely upon your cloud provider letting you know if they see malicious traffic," Dorman says.
It's also important to centralize all logs provided by your cloud provider and to ensure that alerts are generated off of suspicious events. "For example, if you see someone log in to your root AWS account, and that isn't normal for your environment, you should investigate immediately."
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