Privilege escalation in QEMU

1) Security restrictions bypass

EUVDB-ID: #VU50041

Risk: Medium

CVSSv3.1: 7.7 [CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:U/RC:C]

CVE-ID: CVE-2020-35517

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a remote user to escalate privileges on the system.

The vulnerability exists within the virtio-fs shared file system daemon (virtiofsd). A remote privileged user of the guest operating system can create device special file in the shared directory and use it to r/w access host devices.

Mitigation

Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

QEMU: 5.0.0 - 5.2.0

External links

http://seclists.org/oss-sec/2021/q1/64
http://lists.gnu.org/archive/html/qemu-devel/2021-01/msg05461.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the local network (LAN).

How the attacker can exploit this vulnerability?

The attacker would have to trick the victim to open a a specially crafted file.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.