Hi Everyone and welcome to my first Blog post which I am writing as I discovered a Topic which hasn't been discussed in the wild. I'm Akchhat, a cybersecurity researcher with a strong interest in red teaming, penetration testing, and attacker tradecraft. I spend most of my time breaking systems in controlled environments, studying real-world breaches, and understanding how attackers misuse legitimate enterprise technologies.
What are ESXI?
VMware ESXi, also called VMware ESXi Server, is a bare-metal hypervisor which is developed by VMware. ESXi is one of the primary components in the VMware infrastructure software suite. They host critical workloads, sensitive data, and production services. Because of this central role, attackers have increasingly started abusing ESXi not just as a target, but as a persistence medium for cyber attacks.
In this Blog I'll be explaining about how attackers have used these ESXI Hypervisors to gain RCE on the system and this topic emerged during my learning and hands‑on research as part of the AD‑RTS (Active Directory Red Team Specialist) course, where I explored how attackers move beyond Active Directory and abuse underlying infrastructure layers such as hypervisors.
Why ESXi RCE Is High Impact ?
The RCE on ESXI Hypervisors serves as a stealthy mode of persistence for the attackers and Compromising ESXi is fundamentally different from compromising a server. With hypervisor‑level access, attackers can:
- Control multiple VMs from a single point
- Power on, shut down, or snapshot virtual machines
- Access virtual disks and memory directly
Moreover, Most security tools are designed for operating systems and not for the hypervisors. As a result:
- EDR agents do not run on ESXi
- Detection is largely log‑based
- Malicious activity blends in with legitimate admin behavior
Why ESXI Hosts are Domain-Joined
There are Several reasons why the ESXI Hosts are domain joined such as :
- Centralized Authentication : Allows administrators to log in to ESXI hosts using their AD Credentials.
- Role-Based Access Control(RBAC): Enables the assignment of specific permissions to AD users and groups
- Enhanced Auditing Logs and events are tied to specific AD user accounts, making it clear who performed an action
Common Attack Paths for ESXI leading to RCE:
Credential Abuse Leading to RCE:
In many real‑world cases, no exploit is required.
Attackers may:
- Obtain ESXi or vCenter credentials
- Abuse excessive administrative privileges
- Enable SSH or local shell access
Once authenticated access is achieved, command execution on the host becomes trivial.
Misconfigurations and Overexposed Infrastructure:
Common missteps that lead to ESXi RCE include:
- Internet‑exposed management interfaces
- Weak or reused credentials
- Shared admin access across environments
Attackers routinely exploit these weaknesses during initial access.
Another Attack path is if you have compromised the domain admin and the ESXI allows domain admin login then we can most probably directly SSH into the ESXI in an AD environment
Post ESXI Compromise:
Once attackers achieve RCE, the focus shifts to impact, persistence, and lateral movement.
Attackers may:
- Snapshot running VMs
- Mount virtual disks offline
- Extract credentials and sensitive data
- Inject malware into guest systems
How to Defend Against ESXi RCE
Reduce the Attack Surface:
- Never expose ESXi to the internet
- Restrict access via VPNs and jump hosts
Patch Aggressively:
- Keep ESXi fully up to date
- Track VMware security advisories closely
Harden Authentication:
- Use strong, unique credentials
- Enable MFA on vCenter
Final Thoughts
As virtualization continues to dominate enterprise environments, hypervisors like ESXi are becoming prime attack targets.
Remote Code Execution at the hypervisor layer isn't just another vulnerability, it's a force multiplier. If defenders continue to treat ESXi as "just infrastructure" attackers will continue to treat it as the perfect execution layer.
Hypervisor security is no longer optional.
If you found this useful, consider following me for more deep‑dives into offensive security and attacker tradecraft.
References:
Stay tuned for the next blog post, coming soon!!
linkedin: www.linkedin.com/in/akchhat-701234306
github: https://github.com/akchhat1211