CVE-2019-12929
Description
QEMU's Machine Protocol (QMP) is designed to enable remote applications (ex. Libvirt) to control and manage QEMU process instances. QEMU Guest-Agent is a daemon program which helps remote applications (ex. Libvirt) to run commands on the guest VM, it supports QMP commands. It is meant to be used by trusted users and applications. The TCP server socket is only one of the transport options supported by QMP; other, more secure options, being local UNIX socket. If one is able to run QEMU Guest Agents' 'guest_exec' command, the user already has access to the guest VM. Then sending guest state to an unworthy remote machine via nc is not really a security issue.
Libvirt only uses local UNIX sockets to interact with the guest VMs that it manages. This UNIX socket is owned by the same user-id as the QEMU process instance. Other users on the system cannot connect to the UNIX socket. Libvirt also creates a unique per-VM sVirt label so VMs cannot access each other's UNIX sockets, even though they are owned by the same system user-id.
Statement
QEMU Machine Protocol (QMP) is for administrative control of QEMU instances. It must not be exposed to unprivileged users.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 0 | 9.8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | High | N/A |
| Integrity Impact | None | High | N/A |
| Availability Impact | None | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:N
NVD: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
not a bug
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability,Non-Repudiation
Technical Impact: Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities
Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.
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