Privilege escalation in QEMU

1) Security restrictions bypass

EUVDB-ID: #VU50041

Risk: Medium

CVSSv4.0: 5.9 [CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

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

CPE2.3

• cpe:2.3:a:qemu:qemu:5.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:qemu:qemu:5.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:qemu:qemu:5.1.0:*:*:*:*:*:*:*

External links

https://seclists.org/oss-sec/2021/q1/64
https://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.