Time-of-check Time-of-use (TOCTOU) in VMware Fusion, VMRC for Mac and Horizon Client for Mac
| Risk | Low |
| Patch available | YES |
| Number of vulnerabilities | 1 |
| CVE-ID | CVE-2020-3957 |
| CWE-ID | N/A |
| Exploitation vector | Local |
| Public exploit | Public exploit code for vulnerability #1 is available. |
| Vulnerable software Subscribe |
VMware Fusion Client/Desktop applications / Virtualization software VMRC Client/Desktop applications / Software for system administration VMware Horizon Client Client/Desktop applications / Software for system administration |
| Vendor | VMware, Inc |
Security Bulletin
This security bulletin contains one low risk vulnerability.
1) Time-of-check Time-of-use (TOCTOU) Race Condition
EUVDB-ID: #VU28338
Risk: Low
CVSSv3.1: 6.6 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L/E:P/RL:O/RC:C]
CVE-ID: CVE-2020-3957
CWE-ID: N/A
Exploit availability: Yes
DescriptionThe vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a Time-of-check Time-of-use (TOCTOU) issue in the service opener. An local user can gain elevated privileges on the target system.
MitigationInstall updates from vendor's website.
Vulnerable software versionsVMware Fusion: 11.0.0 - 11.5.3
VMRC: 8.0.0 - 11.1.0
VMware Horizon Client: 3.0.0 - 5.4
External linkshttp://www.vmware.com/security/advisories/VMSA-2020-0011.html
Q & A
Can this vulnerability be exploited remotely?
No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.
How the attacker can exploit this vulnerability?
The attacker would have to trick the victim to open a a specially crafted file.
The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.
