Vulnerabilities > CVE-2020-3957 - Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in VMWare Fusion, Horizon Client and Remote Console
Attack vector
LOCAL Attack complexity
MEDIUM Privileges required
NONE Confidentiality impact
COMPLETE Integrity impact
COMPLETE Availability impact
COMPLETE Summary
VMware Fusion (11.x before 11.5.5), VMware Remote Console for Mac (11.x and prior) and VMware Horizon Client for Mac (5.x and prior) contain a local privilege escalation vulnerability due to a Time-of-check Time-of-use (TOCTOU) issue in the service opener. Successful exploitation of this issue may allow attackers with normal user privileges to escalate their privileges to root on the system where Fusion, VMRC and Horizon Client are installed.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Leveraging Race Conditions via Symbolic Links This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to her. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file she will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.
- Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the attacker could do something such as replace the file and cause an escalation of privilege.
Nessus
| NASL family | MacOS X Local Security Checks |
| NASL id | MACOSX_FUSION_VMSA_2020_0011.NASL |
| description | The version of VMware Fusion installed on the remote macOS or Mac OS X host is 11.x prior to 11.5.5. It is, therefore, affected by multiple vulnerabilities. Note that Nessus has not tested for these issues but has instead relied only on the application |
| last seen | 2020-06-10 |
| modified | 2020-06-03 |
| plugin id | 137076 |
| published | 2020-06-03 |
| reporter | This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/137076 |
| title | VMware Fusion 11.x < 11.5.5 Multiple Vulnerabilities (VMSA-2020-0011) |
| code | |