CVE-2019-10168
Description
The virConnectBaselineHypervisorCPU() and virConnectCompareHypervisorCPU() libvirt APIs accept an "emulator" argument to specify the program providing emulation for a domain. Since v1.2.19, libvirt will execute that program to probe the domain's capabilities. Read-only clients could specify an arbitrary path for this argument, causing libvirtd to execute a crafted executable with its own privileges.
Statement
- This vulnerability requires access to the libvirt socket, normally in /var/run/libvirt/libvirt_sock_ro. Typically in hypervisor environments, local user accounts are not supported so no untrusted users should be able to access this socket.
- Red Hat Gluster Storage 3 is not affected by this vulnerability as libvirtd daemon is not shipped in Gluster.
Mitigation
The Unix permissions of libvirt's read-only socket can be made more restrictive than the default (0777) by editing `/etc/libvirt/libvirtd.conf`. The settings `unix_sock_group = libvirt` and `unix_sock_ro_perms = 0770` will restrict access to only members of `libvirt`, who already have management access to virtual machines.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability
Technical Impact: Execute Unauthorized Code or Commands
An attacker could insert malicious functionality into the program by causing the program to download code that the attacker has placed into the untrusted control sphere, such as a malicious web site. This could enable the injection of malware, information exposure by granting excessive privileges or permissions to the untrusted functionality, DOM-based XSS vulnerabilities, stealing user's cookies, open redirect to malware (CWE-601), etc.
Acknowledgements
This issue was discovered by Jan Tomko (Red Hat).
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