Horizon Alert
Summary of the vulnerability and why it matters
This advisory details a critical vulnerability in the vm2 library, affecting applications that use it to sandbox untrusted code. The issue allows sandboxed scripts to escape their environment and execute arbitrary commands on the host system if the application exposes non-strict host functions. This could lead to significant security breaches, including unauthorized access and control of your infrastructure.
- Unsafe code can escape its sandbox.
- Critical escape flaw impacts host system control.
- Assess if your code uses vm2 for untrusted scripts.
Attack Path
How an attacker could exploit the issue
An attacker could compromise an application by leveraging a vulnerability in the vm2 library, which is designed to sandbox code. This vulnerability arises when sandboxed code interacts with a non-strict host function without a proper receiver. By manipulating this interaction, an attacker can gain a live proxy to the host's global objects, effectively breaking out of the sandbox. Once outside, the attacker can access sensitive host functions, such as those for executing commands, leading to arbitrary code execution on the host system.
- Application must expose non-strict host functions.
- Sandboxed code calls host function without a receiver.
- Full sandbox escape and arbitrary code execution.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, a vulnerable vm2 sandbox could allow untrusted script to gain access to the host's global objects, enabling the execution of arbitrary code or commands on the host system. This is possible when the embedding application exposes non-strict host functions to the sandbox, and the sandboxed code calls such a function without a receiver.
- Host global objects and command execution.
- Sandboxed code calls a non-strict host function.
- Arbitrary code execution on the host.
Operational Fix
Recommended remediation, mitigation, and detection steps
Given that `vm2` is a sandboxing library integrated into applications, the primary responsibility for addressing this CVE likely lies with the application development team or the platform team managing the application's runtime environment. The initial step should be to inventory all applications that utilize `vm2`, determine if the vulnerable version is in use, and assess whether the specific exploitable condition (exposure of non-strict host functions) exists.
- Application owners to confirm `vm2` usage.
- Verify vulnerable `vm2` versions and exposure.
- Plan application remediation via library updates.
