Cryptojacking attacks continue to increase. Unlike ransomware, cryptojacking cybercriminals make their money staying silent and undetected, leeching the computer power from their target to mine valuable cryptocurrency. Cryptomining can cause serious downtime for developers by draining the enterprise’s processing power. It can also cause subscription bills to skyrocket—especially if you’re utilizing an auto-scale feature.
It’s been known that threat actors are actively exploiting misconfigured Linux-powered servers, regardless of whether they run on-premises or in the cloud. One notorious example is TeamTNT, one of the first hacking groups shifting its focus to cloud-oriented services.
The cryptojacking battlefield is shared by multiple threat actors such as Kinsing and TeamTNT. Two code characteristics these groups share is to remove competing actors who are also mining for cryptocurrency and disable security features found in the victim machine. This provides them an advantage over the hijacked resources, like the advanced system sanitation that we identified targeting Huawei Cloud.
In this article, we focus on one common functionality found among multiple payloads: the disabling of features inside cloud service provider (CSP), Alibaba. We also look at possible reasons that multiple threat actors and malware routines focused on Alibaba Cloud (also known as Aliyun) and the implications of these illicit mining activities on Alibaba Cloud users.
Looking into Alibaba ECS
Alibaba Elastic Computing Service (ECS) instances come with a preinstalled security agent. As a result, the threat actors try to uninstall it upon compromise. This is no surprise as we have seen similar payloads in the past. However, this time we found a specific code in the malware creating firewall rules to drop incoming packets from IP ranges belonging to internal Alibaba zones and regions.
In addition, the default Alibaba ECS instance provides root access. While other CSPs provide different options ranging from the least privileged ones — such as not allowing Secure Shell (SSH) authentication over users and passwords and only allowing asymmetric cryptography authentication — other CSPs do not allow the user to log in via SSH directly by default, so a less privileged user is required.
For instance, if the login secrets are leaked, having low-privilege access would require more effort to escalate the privileges. However, with Alibaba, all users have the option to give a password straight to the root user inside the virtual machine (VM).
Security wise, this is in contradiction with the principle of least privilege, and it should be emphasized that this is the responsibility of the user for a secure configuration. We highly recommend creating a less privileged user for running applications and services within the ECS instance.
In this situation, the threat actor has the highest possible privilege upon compromise, including vulnerability exploitation, any misconfiguration issue, weak credentials, or data leakage. Thus, advanced payloads such as kernel module rootkits and achieving persistence via running system services can be deployed. Given this feature, it comes as no surprise that multiple threat actors target Alibaba ECS simply by inserting a code snippet only found in the service for removing software.
When a cryptojacking malware is running inside Alibaba ECS, the security agent installed will send a notification of a malicious script running. It then becomes the responsibility of the user to stop the ongoing infection and malicious activities. Alibaba Cloud Security Center provides a guide on how to do this. More importantly, it is always the responsibility of the user to prevent this infection from happening in the first place.
Despite detection, the security agent fails to clean the running compromise and gets disabled. Looking at another malware sample shows that the security agent was also uninstalled before it could trigger an alert for compromise. The samples then proceeded to install the cryptojacking malware XMRig. Examining the samples further shows the cryptominer can easily be replaced with another malware to execute in the environment.
It is also important to note that Alibaba ECS has an auto scaling feature, wherein users and organizations can enable the service to automatically adjust computing resources based on the volume of user requests. When the demand increases, auto scaling allows the Alibaba ECS instances to serve the said requests according to the enumerated policies. While the feature is given to subscribers at no extra cost, the increase in resource usage prompts the additional charges. By the time the billing arrives to the unwitting organization or user, the cryptominer has likely already incurred additional costs. Additionally, the legitimate subscribers have to manually remove the infection to clean the infrastructure of the compromise.
The samples our team acquired can be tied to campaigns targeting Alibaba, and we found these samples sharing common traits, functions, and functionalities with other campaigns that also target CSPs such as Huawei Cloud.
The samples from both campaigns share common traits, especially when it comes to removing “adversaries” and setting up the environment for next-phase infections, such as making sure to use a public domain name system (DNS). Although the style in coding is different, the purpose of the functions is similar on both attacks.
Mitigating the impact of threats on Alibaba ECS workloads
Now that we’ve covered the basics of cryptojacking malware on Alibaba ECS, here are some best practices to mitigate risks:
- Follow the shared responsibility model: While CSPs are responsible for securing the service, users must ensure security configurations of workloads, projects, and environments are safe. Read through the Alibaba Cloud guides, customize, and enable the security layers of workloads and projects accordingly. Make sure it has more than one layer of malware-scanning and vulnerability-detection tools.
- Customize the security features of cloud projects and workloads: Avoid running applications under root privilege and using passwords for SSH. Use public key cryptography for access.
- Adhere to the principle of least privilege: Only grant users with the highest access privileges according to their respective levels of involvement in a project or an application.
Indicators of Compromise (IOCs)
You can find the full list of IOCs and Trend Micro detections here
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